PEACOCK FLOUNDERS: NOW YOU SEE THEM…


Peacock Flounder (Melinda Riger / G B Scuba)

        PEACOCK FLOUNDERS

MASTERS OF SUBAQUATIC CAMOUFLAGE

I featured the extraordinary, colour-transforming PEACOCK FLOUNDER Bothus lunatus a while back as part of a Bahamas Reef Fish series. These really are remarkable creatures, and I have decided to return to them mainly because of the wonderful illustrative photos I was able to incorporate. There are plenty of flounder facts too, but if you just enjoy the pictures and skip the blurb I’ll understand.

Peacock Flounder (Melinda Riger / G B Scuba)

ROVING EYES

In the fish shown here, you’ll see that – surprisingly – both eyes are on the upper-side of the fish, above the rather grumpy mouth, whereas the head is horizontal to the ocean floor. Oddest of all, juveniles are constructed conventionally with bilateral eyes, and look like ‘normal’ fish rather than flatfish.

Peacock Flounder (Melinda Rogers / Dive Abaco)

As the fish matures, in some magic way the mechanics of which I can only guess at**, the right eye grows round to the topside and the flounder transforms from a ‘vertical’ fish to a flatfish. For this reason, the PF is known as a ‘left-eye’ flounder. Maybe in other flounder species in the world – the southern hemisphere maybe? – the eye that moves round to the upper-side is the left eye.

Peacock Flounder (Virginia Cooper / G B Scuba)

The eyes of this fish have another special trick up their sleeves (so to speak). They operate completely independently. Thus the creature can look left and right, or forwards and backwards, simultaneously. It’s an excellent system for detecting predators coming from any angle. It’s a superpower we might all benefit from.

Peacock Flounder (Melinda Rogers / Dive Abaco)

DO THEY HAVE ANY OTHER TRICKS WE SHOULD KNOW ABOUT?

Yes they do indeed. If you have been admiring the fish shown so far, you’ll have noticed that the colour of each one differs from the others. In addition to the predator-protection that the eyes provide, the peacock flounder can make itself (near) invisible. They can rapidly change colour to match their surroundings. There are 3 reasons for this: to avoid / confuse predators; to conceal themselves on the sea-floor to catch passing prey; and, as dive expert Fred Riger has pointed out, “the male peacock flounder can, and does greatly intensify his colours to declare territory and attract females. When doing this the males will also signal with the left pectoral fin, sticking it straight up and waving it around.” 

The same fish, photographed over several minutes as it moves over the ocean floorPeacock Flounder (Wiki)

Matching the background happens as the fish swims, and in a few seconds. When they rest on the sea-floor, the camouflage may even become total. In #4 above you can just about make out the eyes. The whole effect is known as ‘cryptic coloration’ or CRYPSIS. In contrast, the image below shows just how adaptable the transformation can be. Note how the fish can even mimic the pinkish tinge of the sand perfectly. If threatened, the fish will bury itself in the sand, with just its eyes showing.

Peacock Flounder (Melinda Rogers / Dive Abaco)

HOW DO THEY MANAGE TO CHANGE COLOUR IN SECONDS?

It’s complicated! A simple answer is: a mix of hormones, pigment-cells and vision, all coordinating rapidly. The colour change works in two ways: pigments are selectively released to the skin cells; and other pigments can be selectively suppressed. An analogy might be image manipulation using variations in brightness, saturation etc. Not convinced? Then watch this short video and prepare to be impressed. Astonished, even.

WHAT IF A FLOUNDER CAN’T SEE CLEARLY FOR SOME REASON?

As with many (all?) superpowers, there is usually some kryptonite-style flaw. A flounder with a damaged eye, or one temporarily covered (by sand, for example) will have difficulty in changing colour – possibly at all, or at any rate with the swiftness it needs to have. 

Peacock Flounder (Melinda Riger / G B Scuba)

THESE SIDEWAYS FISH – HOW DO THEY… YOU KNOW…?

Take a look at the fish above with its top fin raised. It’s a ‘ready’ signal in a harem. Male flounders have a defined and defended territory within which live up to 6 females – a so-called ‘harem.’ I can do no better than borrow the description of the rituals from an article derived from scientific papers by Konstantinou, 1994Miller, et al., 1991 in the website animaldiversity.org/…ounts/Bothus_lunatus To which I can only add, ’15 seconds, eh?’

Peacock Flounder (Melinda Riger / G B Scuba)

“Mating activities usually begin just before dusk. At this time, a male and a female approach each other with the ocular pectoral fin erect. The two fish arch their backs and touch snouts. After this interaction the female swims away, and the male sometimes follows, approaching the female again from the left side. At this point the male pectoral fin is erect and the female pectoral fin moves up and down, possibly signalling willingness to mate. The male then positions himself underneath the female and mating begins. This process consists of a mating rise, during which the female and male rise in the water column together. On average, these rises last about 15 seconds. At the highest point of this rise, usually around 2 m above the substrate, gametes from both fish are simultaneously released, producing a cloud of sperm and eggs. Once the couple returns from the rise, the male “checks” to make sure mating was successful, and the pair separates quickly, swimming away from each other in opposite directions. Not all mating rises are successful, and the process of “checking” is thus important. The exact purpose of the mating rise in these flounders unknown; possible reasons for rising include better dispersal of gametes and predator avoidance.” 

Peacock Flounder – Kim Rody ArtPeacock Flounder (Kim Rody Art))

**This may in fact have been through sheer laziness

Credits: Melinda Riger & Virginia Cooper / Grand Bahama Scuba; Melinda Rogers / Dive Abaco; Adam Rees / Scuba Works; Kim Rody; animaldiversity.org; magpie pickings and other credits in the text

Peacock Flounder (Melinda Riger / G B Scuba)

CARIBBEAN REEF SQUID: SUPERPOWERS & SQUID SEX


Caribbean Reef Squid, Bahamas (Melinda Riger / G B Scuba)

CARIBBEAN REEF SQUID: SUPERPOWERS & SQUID SEX  

The Caribbean reef squid Sepioteuthis sepioidea is a small squid species of (mainly) the Caribbean Sea and the Floridian coast, and the most common in its range. These squid tend to form small shoals in and around reefs. From now on and through the summer would be a good time to investigate.

Caribbean Reef Squid, Bahamas (Melinda Riger / G B Scuba)

Squid are voracious eaters, dragging their prey to their mouths with some or all of their 10 limbs and using their beak to cut it up. The target species are small fish, molluscs and crustaceans. The squid have a ‘raspy tongue’ known as a radula which further breaks up the food for easy consumption.

Caribbean Reef Squid, Bahamas (Melinda Riger / G B Scuba)

REEF SQUID SUPERPOWERS (SUPERCOOL)

  • Squid are capable of brief flight out of the water (a fairly recent discovery)
  • They can also hide from / confuse predators by ejecting a cloud of black ink
  • Squid can change colour, texture and shape, and can even match their surroundings
  • This enviable power is used defensively as camouflage or to appear larger if threatened
  • It is also used in courtship rituals (something that humans might find disconcerting)
  • Colour patterns are also used for routine squid-to-squid communication AND GET THIS:
  • A squid can send a message to another on one side & a different one to a squid on its other side

Caribbean Reef Squid, Bahamas (Melinda Riger / G B Scuba)

SQUID SEX (1) “ROMANCING THE SQUID”

  • A male will gently stroke a female with his tentacles
  • The female will (most likely) flash an ‘alarm’ pattern. She’s playing hard to get.
  • The male soothes her (don’t try this at home, guys) by blowing and jetting water at her
  • If this doesn’t go well, he’ll move off, then repeat the routine until she sees his good points
  • However this on / off courtship can last for hours until at last he succeeds and then…
  • … he attaches a sticky packet of sperm onto the female’s body (romance is not dead on the reef)
  • She then reaches for it and moves it to her seminal receptacle
  • Meanwhile he stays close, emitting a pulsing pattern, as well he might after all that palaver
  • She then finds a safe place to lay her eggs. Job done. **

Caribbean Reef Squid, Bahamas (Melinda Riger / G B Scuba)

SQUID SEX (2) IT ALL ENDS BADLY. VERY BADLY.

  • As soon the female squid has laid her eggs, she usually dies soon after
  • Male squid live a bit longer and… may have other packets to stick on other lady squid
  • But then in the end he dies too
  • It’s all horribly reminiscent of Romeo and Juliet. The lovers die in the end (but there’s no romantic balcony scene first)

Caribbean Reef Squid, Bahamas (Melinda Riger / G B Scuba)

THE CORRECT PLURAL OF SQUID

I had an unwise look online, always a hotbed of conflicting opinions. Inserting an algorithm into the interstices of the internet proves conclusively that the plural of squid is… squid. One squid, ten squid, a group of squid, a plate of squid. Unless, that is, you are talking about more than one of the many squid species, when you could possibly say ‘I collect both reef and giant squids’. “Squidses” sounds fun but is sadly not permitted.

RELATED POST (from the past): THE PLURAL OF OCTOPUS

Caribbean Reef Squid, Bahamas (Melinda Riger / G B Scuba)

** For an excellent article about squid including the intricate details of courtship and reproduction (and an image of a squid penis) check out  SQUID WIKI 

Credits: Fabulous underwater pics – Melinda Riger of Grand Bahama Scuba; research sources include MarineBio; Animal Diversity Web (Michigan Uni); and Wiki, which comes into its own in some fields of natural history where experts write the entry)

FAIRY BASSLET (‘MIND YOUR GRAMMA’): BAHAMAS REEF FISH


fairy-basslet-melinda-riger-g-b-scuba-copy-2

FAIRY BASSLET (‘MIND YOUR GRAMMA’): BAHAMAS REEF FISH (33)

The Fairy Basslet is a tiny brightly-coloured fish with a pretentious alternative name. It is otherwise known as the Royal Gramma (Gramma loreto). These fish are found  in the coral reefs of the (sub)tropical western Atlantic. They are also found in aquariums anywhere you like, being small, bright, placid and generally good-natured.

fairy-basslet-melinda-riger-gb-scuba

Conveniently, the basslet is unlikely to be confused with any other species. Its striking two-tone colour scheme of purple and yellow is hard to miss. The purple front half (which is presumably where the ‘royal’ comes from, being a regal or imperial colour) may also be violet or even blue in some fish and / or in some light conditions. Another identification pointer is a black spot on the dorsal fin. 

fairy-basslet-melinda-riger-grand-bahama-scuba

You’ll notice that the basslet above appears to be upside down. Which is because it is – this isn’t an inadvertent photo-flip. These little fish tend to orientate themselves to be parallel with the closest surface. This leads to them happily swimming upside down, or aligning vertically. As one article I read says severely, “this behaviour is not to be mistaken for illness”.

fairy-basslet-melinda-riger-g-b-scuba

Fairy basslets / royal grammas are also CLEANER FISH. They pick parasites and dead skin off larger fish that visit so-called cleaning stations to be attended to by tiny fish and cleaner shrimps, and in some instances to have their gills and even their teeth cleaned. The deal is that, in return, the large fish do not eat the cleaners. Even snack-sized ones rootling around inside their mouths.

fairy-basslet-melinda-riger-gb-scuba

 WHAT ABOUT BREEDING?
I really can’t improve on this rather touching description from Wiki: “The male will build the nest among rocks using pieces of algae. The male will then lead the female to the nest, where she will deposit 20-100 eggs in the nest. During the breeding period, this behaviour is repeated almost every day for a month or longer (my italics). The eggs are equipped with small protuberances over the surface with tiny threads extending from them which hold onto the algae of the nest and keep the eggs in place. The eggs will hatch in five to seven days, normally in the evening…”

fairy-basslet-melinda-riger-gb-scuba

HOW COME THE NAME ‘GRAMMA LORETO’?

This official name became a brainworm with me after I started this post. I had to check it out. The ‘Gramma’ part is unrelated to the fond name for a grandmother; rather, it simple denotes a member of the genus of fishes in the family Grammatidae.

The Loreto part is more mysterious. It is an an ancient town in Italy; and the name of several British schools, including – almost too good to be true – a school called Loreto Grammar. In a nutshell, the link between the town and places of education is that the Sisters of Loreto, founded in the c17 and named for a shrine in the Italian village, are dedicated to education in their Ministry.

How that ties in with a tiny Caribbean reef fish, I have yet to find out. I probably never will… Here’s a short video to alleviate the disappointment.

I failed to be able to resist finding out whether any country of the world has a purple and yellow flag. The answer is, no. However I am delighted to be able to report that the flag of the Independent Party of Uruguay is basslet-coloured.

inependent-party-uruguay-flag

fairy-basslet-melinda-riger-g-b-scuba-copy

Credits: all fantastic photos by Melinda Riger of Grand Bahama Scuba; magpie pickings of an unacademic sort for facts and speculation

ELKHORN CORAL – REEF LIFE . ABACO . BAHAMAS


 

Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

ELKHORN CORAL (Acropora palmata) is a widespread reef coral, an unmistakeable species with large branches that resemble elk antlers. The dense growths create an ideal shady habitat for many reef creatures. These include reef fishes of all shapes and sizes, lobsters, shrimps and many more besides. Elkhorn and similar larger corals are essential for the wellbeing both of the reef itself and also its denizens. These creatures in turn benefit the corals and help keep them in a healthy state.

Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

Examples of fish species vital for healthy corals include several types of PARROTFISH, the colourful and voracious herbivores that spend much of their time eating algae off the coral reefs using their beak-like teeth. This algal diet is digested, and the remains excreted as sand. Tread with care on your favourite beach; in part at least, it will consist of parrotfish poop.

Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

Other vital reef species living in the shelter of elkhorn and other corals are the CLEANERS, little fish and shrimps that cater for the wellbeing and grooming of large and even predatory fishes. Gobies, wrasse, Pedersen shrimps and many others pick dead skin and parasites from the ‘client’ fish including their gills, and even from between the teeth of predators. This service is an excellent example of MUTUALISM, a symbiotic relationship in which both parties benefit: close grooming in return for rich pickings of food.

Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

VULNERABILITY TO CLIMATE CRISIS

Formally abundant, over the course of just a couple of decades elkhorn coral (along with all reef life) has been massively affected by climate change. We can all pinpoint the species responsible for much of the habitat decline and destruction, and the primary factors involved. In addition, global changes in weather patterns result in major storms that are rapidly increasing in both frequency and intensity worldwide.  

Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

Physical damage to corals may seriously impact on reproductive success: elkhorn coral is no exception. The effects of a reduction of reef fertility are compounded by the fact that natural recovery is in any case inevitably a slow process. The worse the problem gets, the harder it becomes even to survive, let alone recover, let alone increase. 

Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

HOW DOES ELKHORN CORAL REPRODUCE?

There are two types of reproduction, which one might call asexual and sexual:

  1. Elkhorn coral reproduction occurs when a branch breaks off and attaches to the substrate, forming a the start of a new colony. This process is known as Fragmentation and accounts for roughly half of coral spread. Considerable success is being achieved now with many coral species by in effect farming fragments and cloning colonies (see Reef Rescue Network’s coral nurseries)
  2. Sexual reproduction occurs once a year in August or September, when coral colonies release millions of gametes by Broadcast Spawning 

Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

All photos: Melinda Rogers, with thanks as ever for use permission

Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

WTF? (WHAT’S THAT FISH?): THE FROGFISH


Frogfish (Adam Rees, Scuba Works)

WTF? (WHAT’S THAT FISH?): THE FROGFISH

I have just been lightly involved in a long online thread showcasing the weirdest / most science fiction-y creatures around the world. Trust me, there are plenty. There were quite a few duplications. My own contribution was the frogfish, which no one else had nominated. They are so special – and so weird – that I am reposting my article about them. Don’t miss the last video!

frogfish-anglerfisch

This ‘WTF?’ series started with a relatively conventional species, the REMORA. It has been getting progressively more bizarre. We moved onto an omnium gatherum of WEIRDO FISHES, then the remarkable LETTUCE SEA SLUG, and most recently the BATFISH. Time to ramp up the stakes: with many thanks to scuba expert Adam Rees for use permission for his terrific photos, I present… the FROGFISH.

Frogfish (Adam Rees, Scuba Works)

The frogfish is a kind of anglerfish found in almost all tropical and subtropical oceans and seas. There are about 50 different species worldwide, covering an astonishing range of strange appearances. They generally live on the sea floor around coral or rock reefs. In size they vary from tiny to about 15 inches long – although ‘long’ is a flexible concept because they are to an extent shape-changers in height and width.Frogfish (Adam Rees Scuba Works)

FROGFISH SUPERPOWERS YOU MAY WISH TO HAVE

  • INVISIBILITY CLOAK . Frogfish are masters of disguise and camouflage. This enables them to catch their prey with minimal effort and also to avoid predators. Their camouflage methods – broadly known as ‘aggressive mimicry’ – include
    • Ability to change colour for days or even weeks to mimic their surroundings
    • Getting covered in algae and other organic matter that matches their habitat or
    • Looking inherently like a plump rock or in some cases, plant

Fear for the life of the spider crabFrogfish (Adam Rees, Scuba Works)

  • IRRESISTIBLE ATTRACTION
    • A sort of frontal dorsal fin called an illicium to which is attached a
    • Lure called an esca which may mimic a worm, shrimp or small fish etc and which is
    • Retractable in many species and
    • Regenerates if it gets mislaid

The ‘dollop of cream’ thing is the esca. Note the characteristic large mouthFrogfish (Adam Rees, Scuba Works)

Spot the escaFrogfish (wiki)

  • BUOYANCY CONTROL & SHAPE-SHIFTING
    • Most frogfish have a ‘gas bladder’ to control their buoyancy.
    • Some species can change shape or even inflate themselves by sucking in quantities of water in a so-called defensive ‘threat display’.

frogfish-black

Frogfish (Adam Rees Scuba Works) Frogfish (Adam Rees Scuba Works)

HOW DO FROGFISH REPRODUCE? 

Although not conventionally attractive creatures, frogfish clearly manage to reproduce. Little is known about the techniques in the wild, but one is probably ‘with care’, especially for a male frogfish who may not survive for long if he hangs around after fertilisation has taken place. It has been noted that females tend to select far smaller males to fertilise their huge numbers of eggs, perhaps for that very reason.

Frogfish (Adam Rees, Scuba Works)

FROGFISH FEEDING SKILLS – GOOD OR BAD?

When deploying the lure, potential prey that comes too close to that wide mouth stands no chance. A frogfish will strike in a fraction of a second. Frogfishes have voracious appetites for crustaceans, other fish, and even each other. I can do no better than borrow this vivid description of a feeding frogfish:

“When potential prey is first spotted, the frogfish follows it with its eyes. Then, when it approaches within roughly seven body-lengths, the frogfish begins to move its illicium in such a way that the esca mimics the motions of the animal it resembles. As the prey approaches, the frogfish slowly moves to prepare for its attack; sometimes this involves approaching the prey or “stalking” while sometimes it is simply adjusting its mouth angle. The catch itself is made by the sudden opening of the jaws, which enlarges the volume of the mouth cavity up to twelve-fold, pulling the prey into the mouth along with water. The attack can be as fast as 6 milliseconds. The water flows out through the gills, while the prey is swallowed and the oesophagus closed with a special muscle to keep the victim from escaping. In addition to expanding their mouths, frogfish can also expand their stomachs to swallow animals up to twice their size.

images

HOW DO FROGFISHES GET AROUND? SWIM? WALK? CRAWL?

Frogfishes do not in fact move around a great deal. Using their camo advantages, they prefer to lie on the sea floor and wait for prey to come to them. As mentioned in the quote above, they may slowly approach prey using their pectoral and pelvic fins to “walk” along the sea bottom. They can swim using their tail fin (or in some species by simple ‘jet propulsion’ by forcing water out of their gills) but rarely do so – they don’t feed on the move, and they are adapted to the sea floor environment where they food is readily available. However their “walking” ability is limited to short distances.

frogfish-anglerfisch

DO FROGFISH HAVE OTHER COLOUR SCHEMES?

Indeed they do. In stark contrast to the camo species, some frogfishes are highlighter bright. Here are two of my favourite photos by Adam that show this clearly. I’ve no idea if these are a male and female. I suspect they are different species. I think the brown one is a striated frogfish and the other is… a yellow frogfish. Some people keep these creatures in  aquaria, but apparently it is impossible to sex them, and they have to be kept on their own for everyone’s peace of mind…

Frogfish (Adam Rees Scuba Works) Frogfish (Adam Rees Scuba Works)

FROGFISH INFOGRAPHICS

frogfishFrogfish Infographic 'Monsters of the Deep'

FROGFISH VIDEOS

These two videos, from Lester Knutsen and Daan Van Wijk respectively, show some of the characteristics I have written about above. Both are short and both are fascinating.

To read more about frogfishes and for some fabulous photos I highly recommend the website FROGFISH.CH You can reach the main page(s) but the link seem to be broken so I have not been able to contact Teresa Zubi, whose site it is. She clearly has a sense of humour and uses a neat pair of gifs which I hope she won’t mind my using…

Credits: All main photos, Adam Rees  of Scuba Works with many thanks; wiki for ‘spot the esca’, red quote & basic info; videos Lester Knutsen & Daan Van Wijk; Teresa Zubi for website & gifs; infographics, authors u/k

Frogfish Tee Shirt

IS THIS THE REAL LIFE? IS THIS JUST FANS AT SEA?


Purple sea fan, Bahamas (Melinda Riger / Grand Bahama Scuba)

IS THIS THE REAL LIFE? IS THIS JUST FANS AT SEA?

I am re-posting this sea fan article as 2021 rolls over into 2022 with much the same disruption, anxiety, and (for many) grief that we were all facing a year ago. The converse and somewhat rhapsodic title reflects the experience of many people since Covid engulfed the world. Life has become simultaneously real and surreal. It continues in many respects as normal yet who would have guessed that as we entered a new decade in 2020, the face mask would quickly become an essential (or anyway a medically recommended) part of daily life and remain so? 

This post was written at a time of sunshine, normality and optimism, before Covid and even before the violent destructive force of Dorian in autumn 2019. Here’s some cheer from sea fans on the coral reefs of the Bahamas.  

GALLERY OF GORGONIANS 

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

The waters of Abaco teem with myriads of fish that depend on the coral reefs for shelter and safety, for breeding, for growing up in, and for nourishment. Sea fans (or gorgonians, to use the technical name) are animals too. They may look like plants and stay rooted to the spot, but like anemones these ‘soft corals’ are creatures of the reef and essential indicators of its health.

Purple sea fan, Bahamas (Melinda Riger / Grand Bahama Scuba)

Purple sea fan, Bahamas (Melinda Riger / Grand Bahama Scuba)

The purple sea fan Gorgonia ventalina (classified by Linnaeus in 1785) is one of the most common species of sea fan, and a spectacular one at that. The main branches are linked by a lattice of smaller branches. Below the ‘skin’ is a skeleton made of calcite compounded with a form of collagen.

Purple sea fan, Bahamas (Melinda Riger / Grand Bahama Scuba)

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

Sea fans are filter-feeders, and have polyps with eight tiny tentacles that catch plankton as it drifts past. They develop so that their orientation is across the prevailing current. This maximises the water passing by and consequently the supply of food as the fans gently wave in the flow.

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

Gorgonians have a chemical defence mechanism that protects against potential troublemakers. The main effect is to make themselves unpleasant to nibble or uproot.

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

One species impervious to this deterrent is the fascinating FLAMINGO TONGUE SNAIL. Other ‘safe’ species include the fireworm and BUTTERFLYFISHES.

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

One benefit of sea fans to mankind is that their defensive chemicals have been discovered to provide the basis for drug research and development, specifically in the field of  anti-inflammatories. Another benefit, of course, is that they are very beautiful to look at. And in bad times, that can only be good .

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

Credits: these wonderful photos were taken by Melinda & Keith Rodgers / Dive Abaco, Marsh Harbour; and Melinda & Fred Riger / Grand Bahama Scuba. Huge thanks to them all for allowing me to freely use their skilful underwater photography in this blog for the best part of a decade.

A SPECIAL FAN FOR A HAPPY AND HOPEFUL 2022

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

TUNICATES: SESSILE ASEXUAL SEA-SQUIRTS


Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

TUNICATES: SESSILE ASEXUAL SEA-SQUIRTS

Painted Tunicates Clavina picta are one of several species of tunicate ‘sea-squirts’ found in Bahamas and Caribbean waters. These creatures with their translucent bodies are usually found clustered together, sometimes in very large groups. One reason for this is that they are ‘sessile’, unable to move from where they have taken root on the coral.

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

HOW DO THEY FEED?

Like most if not all sea squirts, tunicates are filter feeders. Their structure is simple, and enables them to draw water into their body cavity. In fact they have 2 openings, an ‘oral siphon’ to suck in water; and an exit called the ‘atrial siphon’. Tiny particles of food (e.g. plankton) are separated internally from the water by means of a tiny organ (‘branchial basket’) like a sieve. The water is then expelled. 

Diagram of adult solitary tunicate

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

WHAT DOES ‘TUNICATE’ MEAN?

The creatures have a flexible protective covering referred to as a ‘tunic’. ‘Coveringcates’ didn’t really work as a name, so the tunic aspect became the name. 

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

IF THEY CAN’T MOVE, HOW DO THEY… (erm…) REPRODUCE?

Tunicates are broadly speaking asexual. Once a colony has become attached to corals or sponges, they are able to ‘bud’, ie to produce clones to join the colony. These are like tiny tadpoles and their first task is to settle and attach themselves to something suitable – for life – using a sticky secretion. Apparently they do this head first, then in effect turn themselves upside down as they develop the internal bits and pieces they need for adult life. The colony grows because (*speculation alert*) the most obvious place for the ‘tadpoles’ to take root is presumably in the immediate area they were formed.

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

APART FROM BEING STATIONARY & ASEXUAL, ANY OTHER ATTRIBUTES?

Some types of tunicate contain particular chemicals that are related to those used to combat some forms of cancer and a number of viruses. So they have a potential use in medical treatments, in particular in helping to repair tissue damage.

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

Credits: all fabulous close-up shots by Melinda Riger / Grand Bahama Scuba; diagram from depts.washington.edu; magpie pickings with a particular mention of an article by Sara MacSorley

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

TOPICAL FISHES: WHOLLY ANGELS


The images below show the three species of angelfish commonly found among the coral reefs of the Bahamas. These were photographed by diver Melinda Riger in the waters round Grand Bahama. The Queen, French and Gray Angels are shown in both adult and juvenile forms.

Queen Angelfish
Queen Angelfish (juv.)
French Angelfish
French Angelfish (juv.)
Gray Angelfish
Gray Angelfish (juv. to adult phase)

All photos: Melinda Riger / Grand Bahama Scuba

CHRISTMAS TREE WORMS: SEASONAL SPIROBRANCHES


Christmas Tree Worm (Melinda Riger / Grand Bahama Scuba)

CHRISTMAS TREE WORMS: SEASONAL SPIROBRANCHES

music-notes-clip-art-png-musicDeck the Reefs with Worms Like Christmas Trees… Fal-La-La-etc-etc ” is a traditional Carol familiar to all. Well, most. Ok, some, then. Oh right – maybe with different words? Anyway, now is the perfect time to take a look at these remarkable subsurface symbols of seasonal good cheer (nb they are wonderful animals not gorgeous plants).

christmas-tree-worm-melinda-riger-g-b-scuba

10 CHRISTMAS TREE WORM FACTS TO PONDER

  • The 2 colourful spirals are not the worm, but complex structures for feeding & respiration
  • The spirals act as specialised mouth extensions for ‘filter-feeding’
  • Prey is trapped by the feathery tentacles & guided by cilia (microscopic hairs) to the mouth
  • The tentacle things are radioles and act as gills for breathing as well as prey traps
  • It is not believed that prey slide down the spiral to their doom, like on a helter-skelter

Christmas Tree Worm (Neil Hobgood Wiki)Christmas Tree Worm (Melinda Riger / Grand Bahama Scuba)

  • The actual worm lives in a sort of segmented tube, with extremely limited mobility skills
  • It contains digestive, circulatory & nervous systems – and a brain in the middle of it all
  • The worm also has a tiny drainage tube (I think I have this right) for excretion etc
  • They embed themselves into heads of coral such as brain coral. And stay there
  • And yes, the Christmas trees are retractable… (see below for some action)

spirobranchus_giganteus_orange_christmas_tree_worm-nick-hobgood-wiki

HOW DO THE WORMS… YOU KNOW…  ERM… REPRODUCE?

This is a delicate area. They are very discreet, but as far as I can make out they eject gametes from their what-I-said-above. There are mummy and daddy worms, and their respective gametes (eggs and spermatozoa) drift in the current and into each other to complete the union. The fertilised eggs develop into larvae, which settle onto coral and burrow into it as their parents did, build their protective tubes, and the process begins again.

christmas_tree_worm-nick-hobgood-wiki

YOU DON’T REALLY UNDERSTAND THESE CREATURES, DO YOU?

I won’t lie. I found it hard to work out how the CTWs function in practice. There are plenty of resources showing them in their full glory, but that only takes one so far. Then I came across a short video that shows it all brilliantly simply (except for the reproduction part).

The worms, in their coral burrows, hoist their pairs of ‘trees’. You can easily see small particles – zooplankton – drifting in the water, and the radioles swaying to catch potential food. Suddenly it all makes sense (except the repro bit – I haven’t found footage of that).  Next: the New Year Worm (there is no Easter worm).

A WHOLE FESTIVAL OF CHRISTMAS TREE WORMSChristmas Tree Worms (Neil Hobgood Wiki)

Credits: Melinda Riger (Grand Bahama Scuba); Nick Hobgood; Betty Wills; Video by ‘Super Sea Monkey’; Reef Collage by RH; MarineBio; Wikibits & Magpie Pickings

Happy Christmas to all those who put up with RH with such fortitude over the years
blue_christmas_tree_worm-betty-wills-wiki

ENDANGERED SPECIES, ABACO (3): NASSAU GROUPER


Nassau Grouper (Melinda Riger / G B Scuba)

ENDANGERED SPECIES, ABACO (3): NASSAU GROUPER

The Nassau grouper Epinephelus striatus is one of a number of grouper species found in Bahamian waters. Of these, only the Nassau grouper is on the IUCN Red List, as Critically Endangered. When I last wrote about them they were in the lesser category ‘Threatened’.

Nassau Grouper (Melinda Riger / G B Scuba

In order to sustain a viable population, it is vital to maintain numbers and preferably to increase them year on year. Once it became clear that year-round commercial overfishing was a prime component of the steep decline in the population, a 3-month closed season during the breeding period was imposed. This has ensured that at the most critical time in the lifecycle of the species, the groupers are left alone to breed in peace and to perpetuate their species.

Nassau Grouper (Melinda Riger / G B Scuba)

The closed season operates from December to February to maximise the chances of breeding success. As with some other fish species, reproduction occurs around the full moon. The fish gather at spawning sites and the process is at its height around sunset.

Nassau Grouper (Melinda Rogers / Dive Abaco)

10 CONVENIENTLY COLLECTED NASSAU GROUPER FACTS

  • An adult can grow to more than a metre long, and weigh 25 kg
  • They tend to be solitary daytime feeders, eating small fish & crustaceans
  • Their large mouths are use to ‘inhale’ or suck in prey
  • The colouring of an individual can vary from red to brown
  • These fish have little black spots around the eyes (I’ve no idea why).
  • Their habitat is in the vicinity of coral reefs, from shallows to 100 m deep
  • Spawning mainly occurs in Dec & Jan during a full moon
  • Large numbers gather in a single location to mate in a mass spawning
  • These groupers are slow breeders, which compounds the overfishing problem
  • They are easy mass targets at spawning time; hence the need for a closed season

Nassau Grouper (Melinda Riger / G B Scuba)

A Nassau Grouper glumly contemplates the possibility of extinctionNassau Grouper (Melinda Riger / G B Scuba)

RELATED POSTS

BLACK GROUPER

TIGER GROUPER

RED HIND

CLEANING STATIONS

Nassau Grouper (Melinda Rogers / Dive Abaco)

Credits: Melinda Riger / Grand Bahamas Scuba (1, 2, 3, 5, 6); Melinda Rogers / Dive Abaco (4, 7)

CORAL SUNSHINE: PICTURE PERFECT ABACO (9)


CORAL SUNSHINE: PICTURE PERFECT ABACO (9)

coral-in-sunlight-melinda-rogers-dive-abaco

Off the east coast of Abaco lies one of the longest barrier reefs in the world. Some authorities suggest it is the third longest, but the exact ranking of the top dozen coral barriers is a matter for considerable debate. None of the lists I have just checked agree, except that the Great Barrier Reef is the outright winner. I suspect that the problem lies in the loosely generalised description of ‘barrier reef’ and in variations of the appropriate criteria for determining length (it may also depend on who is doing the measuring, of course).

Melinda Rogers of Dive Abaco took this bright sunlit ‘Coralscape’ in the Fowl Cays National Park. It’s a place I have tentatively snorkelled around with great pleasure, despite being in the top dozen most useless swimmers in the world (my appalling underwater videos were disqualified from the rankings for being… rank).

GROUPER AT THE CLEANERS: PICTURE PERFECT BAHAMAS (5)


GROUPER AT A CLEANING STATION: PICTURE PERFECT BAHAMAS (5)

BLACK GROUPER AT A CLEANING STATION (Melinda Riger @ G B Scuba)

This black grouper (‘Arnold’) is at a so-called CLEANING STATION, being groomed by gobies. The process is an example of species symbiosis known as MUTUALISM. This is a transaction between individuals of two species that is mutually beneficial. Here, the primary creature pauses at a locally familiar cleaning station and allows itself to be expertly cleaned by tiny fishes such as gobies and wrasses to remove parasites, dead skin and so forth. This nurture even includes, as here, inside the mouth and gills. The gobies benefit by feeding on the proceeds of their endeavours removed from the host (or ‘client’ as one might say). And of course, in return for their favours a collateral benefit is that they can feed freely without being eaten by a potential predator. 

Credit: Melinda Riger / Grand Bahama Scuba

CORAL REEFS AND HURRICANE DAMAGE ON ABACO BAHAMAS


Reef Corals, Abaco Bahamas (Melinda Rogers / Dive Abaco)

CORAL REEFS AND HURRICANE DAMAGE ON ABACO BAHAMAS

The spectacular coral reef chains of the Bahamas include the 3rd largest barrier reef in the world. Abaco’s reef system stretches from Little Harbour to beyond the northern end of the mainland, as Sandy Estabrook’s map shows. Inside the reef: the Sea of Abaco. Beyond the reef and the next landfall east: Western Sahara, south of the Canary Islands.Abaco Map Sandy Estabrook
A rainbow effect of filtered sunlight on sea fansReef Corals, Abaco Bahamas (Melinda Rogers / Dive Abaco)
Since the devastation of Abaco by Hurricane Dorian last September, a number of surveys have been carried out. Some of these relate to the impact of the storm on the natural world – the damaged forest and coppice, the bird-life including the Abaco specialities, and the marine life including marine mammals, fish, and reef structures and environments.
Reef Corals, Abaco Bahamas (Melinda Rogers / Dive Abaco)
A recent assessment by the Perry Institute for Marine Sciences (PIMS) in Abaco and Grand Bahama waters has been carried out on the coral reefs to determine the extent to which the vulnerable structure, ecology and environment has been damaged. Some details have just been published in the Nassau Guardian in an article by Paige McCartney. The LINK is below.
Reef Corals, Abaco Bahamas (Melinda Rogers / Dive Abaco)
DAMAGE FINDINGS IN BRIEF
  • 25 – 30% of the 29 reef sites surveyed are devastated
  • factors include damage from debris, silt burial, and bleaching
  • uprooted casuarina trees were caught in the storm surge, causing damage
  • in particular, corals have been smashed and reef structure destroyed
  • there is biomass loss – basically reduced populations of fish & other organisms

Reef Corals, Abaco Bahamas (Melinda Rogers / Dive Abaco)

RAYS OF LIGHT
Although the reef systems of both islands have been significantly damaged, in other areas little damage was found. Moreover, in some areas the storm had washed away some types of seaweed that are harmful to the reefs. The hope is that restoration of the damaged areas can be achieved with careful management.
Reef Corals, Abaco Bahamas (Melinda Rogers / Dive Abaco)
WHAT CAN BE DONE NOW?
Action towards restoration and future protection includes:
  • removal of debris and other deleterious matter (eg silt)
  • cutting back the non-native, invasive casuarinas from the shoreline
  • restoration programs (recent successes with ‘coral farming’ could be vital)
  • extending marine protected areas
  • developing a rapid response protocol to meet extreme situations

Reef Corals, Abaco Bahamas (Melinda Rogers / Dive Abaco)

The reports ends with some welcome news: Government departments have recently proposed putting $5 million towards a coral restoration project on Abaco, including the establishment of a and-based aquaculture facility to support coral growth in nurseries. Let’s hope that becomes a reality.

The publication of the PIMS report and its findings gives some hope of recovery for the fragile reef environment of the northern Bahamas. Other factors may reverse the optimism of course, not least the accelerating warming of the seas and the exponentially expanding pollution problem such as this, recently reported

This has been an opportunity to revisit the clear waters around Abaco where Melinda Rogers of Dive Abaco took these astonishing photos of coral on the local reefs. If the coral is destroyed or dies, this is what our children and their children will be be missing.

Click the brain coral to link to the Nassau Guardian Article

All photos, Melinda Rogers / Dive Abaco; Map, Sandy Estabrook; Nassau Guardian / Paige McCartney; Perry Institute for Marine Sciences (PIMS)

Reef Corals, Abaco Bahamas (Melinda Rogers / Dive Abaco)

OCTOPUS’S GARDEN (TAKE 9) IN THE BAHAMAS


Octopus (Melinda Riger - Grand Bahama Scuba)

OCTOPUS’S GARDEN (TAKE 9) IN THE BAHAMAS

We are back again under the sea, warm below the storm, with an eight-limbed companion in its little hideaway beneath the waves.

Octopus (Melinda Riger - Grand Bahama Scuba)

It’s impossible to imagine anyone failing to engage with these extraordinary, intelligent creatures as they move around the reef. Except for octopodophobes, I suppose. I’ve written about octopuses quite a lot, yet each time I get to look at a new batch of images, I feel strangely elated that such a intricate, complex animal can exist. 

Octopus (Melinda Riger - Grand Bahama Scuba)

While examining the photo above, I took a closer look bottom left at the small dark shape. Yes my friends, it is (as you feared) a squished-looking seahorse, 

Octopus (Melinda Riger - Grand Bahama Scuba)

The kind of image a Scottish bagpiper should avoid seeingOctopus (Melinda Riger - Grand Bahama Scuba)

OPTIONAL MUSICAL DIGRESSION

With octopus posts I sometimes (rather cornily, I know) feature the Beatles’ great tribute to the species, as voiced with a delicacy that only Ringo was capable of. There’s some fun to be had from the multi-bonus-track retreads currently so popular. These ‘extra features’ include alternative mixes, live versions and – most egregious of all except for the most committed – ‘Takes’. These are the musical equivalent of a Picasso drawing that he botched or spilt his wine over and chucked in the bin, from which his agent faithfully rescued it (it’s now in MOMA…)

You might enjoy OG Take 9, though, for the chit chat and Ringo’s endearingly off-key moments.

All fabulous photos by Melinda Riger, Grand Bahama Scuba taken a few days ago

Octopus (Melinda Riger - Grand Bahama Scuba)

 

YELLOWTAIL PARROTFISH: BAHAMAS REEF FISH (54)


Yellowtail (Redfin) Parrotfish (Melinda Rogers / Dive Abaco)

YELLOWTAIL (REDFIN) PARROTFISH: BAHAMAS REEF FISH (54)

The yellowtail parrotfish (sometimes known as a redfin) is one of around half-a-dozen kinds of parrotfish found among the coral reefs of the Bahamas, and sometimes in seagrass areas. There are many other related species worldwide (about 80). Parrotfish are among the most important fishes on the reef because they play a major role in BIOEROSION , a vital process for the health of the reef.

Yellowtail (Redfin) Parrotfish (Melinda Rogers / Dive Abaco)

A. FEEDING & BEACH BUILDING

  • Their dental arrangements – a mouthful of meshing teeth – form the characteristic ‘beak’
  • Primarily herbivores but also snack on small creatures, organisms, or even molluscs
  • As they feed on their favourite algae, their teeth grind up the coral which they ingest
  • They digest the coral & excrete it as sand, becoming a component of your favourite beach
  • The teeth grow continuously, replacing ones worn away by grinding coral as they graze
  • They are a vital species in preventing algae from choking coral: essential reef cleaners

Yellowtail (Redfin) Parrotfish (Melinda Rogers / Dive Abaco)

B. PARROTFISH: PERSONAL INFORMATION

  • Some secrete a protective mucous cocoon to sleep in or as concealment from predators
  • Mucous also helps to heal damage, repel parasites, & protect them from UV light
  • As they develop from the juvenile stage, most species change colour significantly
  • In some species, juveniles change colour temporarily for protective purposes
  • These are “sequential hermaphrodites”, turning from female to male (‘protogyny’)
  • Single males tend to have several lady friends, and aggressively defend their love rights
  • Parrotfish are PELAGIC SPAWNERS. Females release many tiny buoyant eggs into the water
  • The eggs float freely then eventually sink to the coral until they hatch
  • Unlike almost all other fishes, they use their pectoral fins to propel themselves
  • Feeding behaviour / dietary requirements make them (thankfully) unsuitable for aquariums (or aquaria, if you prefer)

Yellowtail (Redfin) Parrotfish (Melinda Rogers / Dive Abaco)

WHAT WAS THAT ABOUT CHANGING SEX?

  • Parrotfish may undergo sex reversal in which developing female fish become males
  • Parrotfish born male remain male throughout their lives (“primary males”)
  • Female-born fish may change sex & colour to become male (“secondary males”)
  • Secondary males are fertile and generally mate with a single female
  • Females that stay female live in harems protected by a dominant “supermale” BUT…
  • …if the supermale dies, the largest female in the group changes sex to become male…
  • …AND amazingly adopts the coloration of the supermale (best ‘astounding fact’ of all)

Yellowtail (Redfin) Parrotfish (Melinda Rogers / Dive Abaco)

ARE PARROTFISH EDIBLE? JUST ASKING…

  • Parrotfish skin is very tough but their flesh is soft and degenerates quickly
  • Some species (eg blue parrotfish) carry ciguatera toxins – to be avoided
  • They are not considered a fishing target in Bahamas, nor a food-fish
  • Parrotfish are eaten elsewhere in the world however, for example Jamaica (cooked)
  • In Hawaii they are eaten raw – at one time they were reserved for royalty

VIDEO LINK: PARROTFISH POOP

Credits: Melinda Rogers / Dive Abaco for her great illustrative images. All photographs were taken on the reefs of Abaco, before the devastation and destruction of Hurricane Dorian last September; Florida Museum to cross-check facts; VIDEO – Scientific American

Yellowtail (Redfin) Parrotfish (Melinda Rogers / Dive Abaco)

WRY ‘CUDA & SARDONIC SMILES, ABACO BAHAMAS


Barracuda, Abaco Bahamas (Melinda Rogers / Dive Abaco)

WRY ‘CUDA & SARDONIC SMILES, ABACO BAHAMAS

There’s no doubt about it, barracudas have a particularly unwelcoming look to them. They exude menace. There’s something about the torpedo shape, the primitive head, and the uncomfortably snaggle-toothed grin-with-underbite that suggests a creature not to be underestimated.

Barracuda, Abaco Bahamas (Melinda Rogers / Dive Abaco)

And that smiley mouth – rather scornful and derisive, is it not? A powerful creature in its element, where you are the intruder… and it sees it like that too. An adult barracuda may grow to nearly 6 foot long. Your are only temporarily of its world, and (it observes) you are keeping your distance.

Barracuda, Bahamas (Melinda Riger / G B Scuba)

The dental arrangements of a ‘cuda are a wonder in themselves. The teeth are razor sharp; an orthodontist’s nightmare because they are all different sizes and grow at different angles. Some are conventionally set in the jaws, but some actually grow from the roof of the mouth. There are ‘normal’ sized teeth interspersed with wicked-looking fangs that randomly grow facing forwards, backwards and sideways.

Barracuda, Abaco Bahamas (Melinda Rogers / Dive Abaco)

WHY THE UNTIDY MOUTH FURNITURE?Barracuda, Abaco Bahamas (Melinda Rogers / Dive Abaco)

The name Barracuda is thought to derive from the Spanish word barraco meaning (in one of its senses) “overlapping teeth”. The jaws that contain the teeth are strong, and the underbite adds to the effectiveness of ‘cuda predation. Prey is highly unlikely to escape once caught.  When the jaws snap shut, the sharp angled teeth – particularly the back-facing ones (cf fishhook barbs) prevent the victim from pulling away. Then the munching and shredding can begin inside what is essentially a perfectly equipped multi-bladed mincing machine.

Credits: Melinda Rogers / Dive Abaco except #3 & #8  Melinda Riger / Grand Bahama Scuba

Here’s looking at you…

‘DEEP DIVERS IN DIVERS DEEPS’: CUVIER’S BEAKED WHALES


Cuvier's Beaked Whale, Bahamas (BMMRO / Charlotte Dunn)

‘DEEP DIVERS IN DIVERS DEEPS’: CUVIER’S BEAKED WHALES

JOURNEY TO THE WORLD’S MIDNIGHT ZONE

Please join me in a dive down from the sparkling surface of the turquoise sea to the twilight zone at 200 meters. You’ll pass plenty of sea-life on the way: manatees grazing on seagrass just below the surface; reef fish, barracudas, reef sharks, mahi-mahi, maybe an orca at 100 meters. Other familiar creatures that are found even lower include a few reef fish, some shark species and green sea turtles. You are now running out of clear light.

Cuvier's Beaked Whale, Bahamas (BMMRO / Charlotte Dunn)

As you descend from 200 meters the waters become murky, then inky. The variety of inhabitants and their numbers are gradually decreasing. There are eels, some sharks, squid, stranger deep-water creatures. You may be surprised to see familiar bottlenose dolphins, recorded as diving nearly 300 meters. At 332 meters you will equal the deepest point any human being has ever scuba-dived (Ahmed Gabr 2014). There is little light, but you still have a long way to go to reach your goal.

Dolphin dive depth (Neal)

Descending still deeper, species and numbers continue to thin out. Around the world the limits of larger recognisable species is being reached – more shark species, tuna, chinook salmon, emperor penguins, swordfish, the few corals that can survive the depth. As the light fades to black, giant creatures and strange fish abound. Huge crabs. Sunfish. The (no-longer-extinct) Coelocanth. Massive octopuses. 

Cuvier's Beaked Whale, Bahamas (BMMRO / Charlotte Dunn)

Deeper down, nearing 1000 meters now, there are still some familiar species. Leatherback turtles; Baird’s beaked whales (nb not in the Atlantic); and at 920 meters, the deepest recorded sperm whale dive. It’s pitch dark: you have reached the level that sunlight never penetrates. You are in the Midnight Zone.

Sperm whale dive depth (Neal)

DEEP OCEAN DWELLERS

In black depths below 1000 meters, creatures have adpated to create their own light sources – so-called bioluminescence. This is the realm of the self-lit anglerfish, the blobfish and the goblin shark. It’s the Attenborough world of deep sea exploration. The geology is changing: there are hypervents, volcanic rocks, heavy metals. Below are the deep ocean-floor trenches. Yet there are still recognisable species down here, diving astonishingly deep to 1800 meters to feed – not least the narwhal which makes this trip several times a day to feed.

We need to quicken up the descent now – we have to get down nearly twice as far as this to reach our destination…

Cuvier's Beaked Whale leap (M.Rosso GIMA - IUCN)

We pass large squid and isopods, the deepest diving shark – the Greenland, the 10 meter-long 700 kilo colossal squid – yet amazingly there are marine mammals yet to be encountered: at 2400 meters we drift past a huge elephant seal. There are evil-looking creatures down here with names to match – devilfish, viperfish, black swallowers that can eat a larger fish whole, vampire squid and zombie worms. 

At 3000 feet, we finally end our quest. We have reached the depth to which the world’s deepest diving mammal has been recorded: the Cuvier’s beaked whale Ziphius cavirostris


Cuvier's Beaked Whale (NOAA Fisheries)

Cuvier’s beaked whales, or “goose-beaked whales,” are not rare. For a start, unlike many beaked whale species, they inhabit most oceans and seas in the world and have the most extensive range. Unsurprisingly therefore, they are one of the most often sighted beaked whale species and one of the best studied. 

Cuvier's Beaked Whale Bahamas (BMMRO / Charlotte Dunn)

FIN FACT

You may be wondering about the pressure exerted on a creature at a depth of 3000 meters. The answer is, an astounding 300 atm (atmospheres), enough to crush all but the hardiest and best adapted of species. The question how these whales manage to survive at such a depth is one for the future…

The Cuvier’s is one of the 3 beaked whale species found in Bahamas waters. Like the rarer Blainville’s and Gervais’s beaked whales, the Cuvier’s is the subject of ongoing research by the BAHAMAS MARINE MAMMAL RESEARCH ORGANISATION BMMRO

Cuvier's Beaked Whale leap (BW - Getty - Times)

The research into marine mammal populations in the Bahamas and far beyond is focussed on the massive increase in single and mass strandings, including recently in a remote area of Scotland (Hebrides) where more than 40 Cuvier’s were washed ashore.

One significant area of research examines the effect on marine mammals of man-made noise. There is plenty of it in the world’s oceans caused by noise pollution in and around shipping channels that traverse marine mammal migration, feeding and breeding grounds; naval surface and submarine exercises; seismic surveys, sonar waves and undersea resource investigations. The evidence of sound / acoustic damage as an additional hazard for marine mammals is starting to look very clear.

Cuvier's Beaked Whale Bahamas (BMMRO / Charlotte Dunn)

DEEP WATER INFOGRAPHIC

Do not miss this wonderful work by Neal Agarwal. This article is based around it and includes facts and images derived from his incredibly complex structure that has resulted in a remarkably simple resource for layman and ocean-lover alike (I realise these categories may overlap). To see the entire masterpiece, double click of the box below – “it will be worth it”.

CREDITS: Neal Agarwal; BMMRO / Charlotte Dunn; M.Rosso GIMA – IUCN; NOAA Fisheries; BW – Getty – Times; Pierangelo Pirak / BBC Earth (depth infographic), general sources – BMMRO, IUCN, NOAA, WDC

As ever, the Bahamas Philatelic Bureau has produced a wonderful stamp special issue

EEL-SPOTTING: FORAYS WITH MORAYS (7)


Spotted Moray Eel, Bahamas (Melinda Riger / G B Scuba)

EEL-SPOTTING: FORAYS WITH MORAYS (7)

MORAY EELS are plentiful around the reefs of the Bahamas. Some species, anyway. The ones you are most likely to encounter are green morays, and the spotted morays shown here. Less common are chain and golden-tail morays and, rarer still I suspect (because I have only  one image in the archive…) is the ‘purple-mouth’.  

Spotted Moray Eel, Bahamas (Melinda Riger / G B Scuba)

Despite their moderately intimidating appearance – an adult may grow to 1.5 meters or more, with sharp teeth at the front end – these eels are not especially aggressive unless provoked. Best to assume that all humans will behave respectfully around them and remember that people are the intruders in the eels’ domain. 

Spotted Moray Eel, Bahamas (Melinda Riger / G B Scuba)

Morays tend to be loners of the reefs, but they do gather in groups from time to time. And as shown below, they will also hunt with other species, for example this tiger grouper.

Spotted Moray Eel, Bahamas (Melinda Riger / G B Scuba)

Sharp-eyed, sharp-toothed

Spotted Moray Eel, Bahamas (Melinda Riger / G B Scuba)

Looks friendly enough…

Spotted Moray Eel, Bahamas (Melinda Riger / G B Scuba)

A long and surprisingly large body, generally concealed in the crevices of the reef

Spotted Moray Eel, Bahamas (Melinda Riger / G B Scuba)

Credits: Melinda Riger / Grand Bahama Scuba

Lurkin’ GoodSpotted Moray Eel, Bahamas (Melinda Riger / G B Scuba)

ELKHORN CORAL, ABACO BAHAMAS (DORIAN UPDATE)


Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

ELKHORN CORAL, ABACO BAHAMAS (DORIAN UPDATE)

Elkhorn coral (Acropora palmata) is a widespread reef coral, an unmistakeable species with large branches that resemble elk antlers. The dense growths create an ideal shady habitat for many reef creatures. These include reef fishes of all shapes and sizes, lobsters, shrimps and many more besides. Some of these are essential for the wellbeing of the reef and also its denizens.

Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

GOOD POST-DORIAN NEWS ABOUT ABACORAL

A recent report from FRIENDS OF THE ENVIRONMENT brings encouraging news about the reefs of  Abaco post-hurricane, and an indication of the resilience of the coral to extreme conditions (with one exception for a reef too close to the shore to avoid damage from debris).

Shortly before Dorian hit, The Perry Institute for Marine Science and its partners surveyed reefs across Grand Bahama and Abaco to assess their health. Following Dorian, they were able to reassess these areas and the impact of the hurricane. Over the 370 miles that the surveys covered, minimal damage was found on the majority of reefs. Unfortunately Mermaid Reef, where FRIENDS does most of our educational field trips, sustained extensive damage due to debris from its close proximity to the shoreline. We are looking into how we can help with logistics to get the debris removed, and hopefully the recovery will begin soon.

Elkhorn Coral, Pelican Cays, Abaco Bahamas (Friends of the Environment)

Elkhorn coral standing strong post-Dorian at Sandy Cay Reef, Pelican Shores, Abaco

The scientists were also able to visit four of the Reef Rescue Network’s coral nurseries and assess out-planted corals in national parks in both Grand Bahama and Abaco. The great news is that all of the corals on these nurseries survived the storm and will be used to support reef restoration. Also from the surveys, it appears that our offshore reefs around Abaco sustained minimal damage, including Sandy Cay Reef in Pelican Cays Land and Sea Park (pictured above). This gives us hope for the recovery of our oceans post-Dorian and proves how resilient these amazing ecosystems are.

Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

Examples of species vital for healthy corals include several types of PARROTFISH, the colourful and voracious herbivores that spend most of their time eating algae off the coral reefs using their beak-like teeth. This algal diet is digested, and the remains excreted as sand. Tread with care on your favourite beach; in part at least, it will consist of parrotfish poop.

Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

Other vital reef species living in the shelter of elkhorn and other corals are the CLEANERS, little fish and shrimps that cater for the wellbeing and grooming of large and even predatory fishes. Gobies, wrasse, Pedersen shrimps and many others pick dead skin and parasites from the ‘client’ fish including their gills, and even from between the teeth of predators. This service is an excellent example of MUTUALISM, a symbiotic relationship in which both parties benefit: close grooming in return for rich pickings of food.

Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

VULNERABILITY TO OFFICIALLY NON-EXISTENT CLIMATE CRISIS

Formally abundant, over just a couple of decades elkhorn coral has been massively affected by [climate change, human activity and habitat destruction] inexplicable natural attrition in many areas. One cause of decline that is incontrovertible is damage from storms, which are empirically increasing in both frequency and intensity, though apparently for no known reason.

Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

Physical damage to corals may seriously impact on reproductive success; elkhorn coral is no exception. The effects of a reduction of reef fertility are compounded by the fact that natural recovery is in any case inevitably a slow process. The worse the problem gets, the harder it becomes even to survive let alone recover. 

Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

SO HOW DOES ELKHORN CORAL REPRODUCE?

There are two types of reproduction, which one might call asexual and sexual:

  1. Elkhorn coral reproduction occurs when a branch breaks off and attaches to the substrate, forming a the start of a new colony. This process is known as fragmentation and accounts for roughly half of coral spread. Considerable success is being achieved now with many coral species by in effect farming fragments and cloning colonies (see above, Reef Rescue Network’s coral nurseries)
  2. Sexual reproduction occurs once a year in August or September, when coral colonies release millions of gametes by broadcast spawning (there’s much more to be said on this interesting topic, and one day I will)

Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

THE FEATURED PHOTOGRAPHS

You may have wondered in which healthily coral-infested waters these superb elkhorn coral photographs were taken. Did I perhaps source them from a National Geographic coral reef special edition? In fact, every image featured was obtained among the reefs of Abaco.

All except the recent Perry Institute / Friends of the Environment photo were taken by Melinda Rogers of Dive Abaco, Marsh Harbour. The long-established and highly regarded Dive Shop she and her husband Keith run was obliterated (see above) less than 3 months ago by Hurricane Dorian, along with most of the rest of the town. It’s a pleasure to be able to showcase these images taken in sunnier times.

Elkhorn Coral, Abaco Bahamas (Melinda Rogers / Dive Abaco)

AN OCTOPUS’S GARDEN, BAHAMAS


Octopus on coral reef, Bahamas (Melinda Riger / GB Scuba)

AN OCTOPUS’S GARDEN, BAHAMAS

Most of us, from time to time, might like to be under the sea, warm below the storm, swimming about the coral that lies beneath the ocean waves. An undeniably idyllic experience that is perfected by the presence of an octopus and the notional garden he lives in. Enough to make any person shout and swim about – and quite excessively at that.

Octopus on the coral reef, Bahamas (Melinda Riger / GB Scuba)

The extra ingredient here is that these photographs were taken on the reef off the southern coast of Grand Bahama last week, less than 2 months after the island (along with Abaco) was smashed up by Hurricane Dorian. Thankfully, Grand Bahama Scuba has been able to return to relative normality and run diving trips again. Moreover, fears for the reefs have proved relatively unfounded. These images suggest little damage from the massive storm. The Abaco reefs have not yet been able to be assessed in any detail.

Octopus on the coral reef, Bahamas (Melinda Riger / GB Scuba)

The feature creature here was observed and photographed as it took it a octopodic wander round the reef. The vivid small fishes are out and about. The reef and its static (technically ‘sessile’) life forms –  corals, anemones and sponges –  look in good order. The octopus takes a pause to assess its surroundings before moving on to another part of the reef.

Octopus on the coral reef, Bahamas (Melinda Riger / GB Scuba)

THE PLURAL(S) OF OCTOPUS REVISITED

A long time ago I wrote a quasi-learned disquisition on the correct plural for the octopus. There were at least 3 possibilities derived from Greek and Latin, all arguable but none so sensible or normal-sounding as ‘octopuses‘. The other 2 are octopi and octopodes. If you want the bother with the details check out THE PLURAL OF OCTOPUS

There’s an aspect I missed then, through rank ignorance I’d say: I didn’t check the details of the Scientific Classification. Now that I am more ‘Linnaeus-woke’, I have two further plural candidates with impeccable credentials. Octopuses are cephalpods (‘headfeet’) of the Order Octopoda and the Family Octopodidae. These names have existed since naturalist GEORGES CUVIER (he of the beaked whale found in Bahamas waters) classified them thus in 1797.  

RH ADVICE stick with ‘octopuses’ and (a) you won’t be wrong (b) you won’t get into an un-winnable argument with a pedant and (3) you won’t sound pretentious

Octopus on the coral reef, Bahamas (Melinda Riger / GB Scuba)

OPTIONAL MUSICAL DIGRESSION

Whether you are 9 or 90, you can never have too much of this one. If you are somewhere in the middle – or having Ringo Starr free-styling vocals doesn’t appeal – you can. Step back from the vid.

All fabulous photos by Melinda Riger, Grand Bahama Scuba, Nov 2019

Octopus on the coral reef, Bahamas (Melinda Riger / GB Scuba)