PEACOCK FLOUNDERS REVISITED: NOW YOU SEE THEM…

July 17, 2019 by Rolling Harbour

PEACOCK FLOUNDERS (Part Deux)

MASTERS OF SUBAQUATIC CAMOUFLAGE

I featured the extraordinary, colour-transforming PEACOCK FLOUNDER Bothus lunatus about 3 years ago in the Bahamas Reef Fish series (No. 21 I think). These really are remarkable creatures, and I am pleased to be able to show some more wonderful illustrative photos.

ROVING EYES

In the fish shown here, you’ll see that – surprisingly – both eyes are on the upperside 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.

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 ‘lefteye’ flounder. Maybe in other flounder species in the world – the southern hemisphere maybe? – the eye that moves round to the upperside is the left eye.

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.

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 floor

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.

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 pignments 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.

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, 1994; Miller, et al., 1991 in the website animaldiversity.org/…ounts/Bothus_lunatus To which I can only add, ’15 seconds, eh?’

“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 Art

**This may in fact be 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

BABY SPERM WHALE IN BAHAMAS WATERS: AMAZING FOOTAGE

July 8, 2019 by Rolling Harbour

BABY SPERM WHALE IN BAHAMAS WATERS: AMAZING FOOTAGE

Over several years I have had the privilege of being able to feature wonderful photographs and video footage in this blog. Birds, course, and also reef fish, sharks, seahorses, coral and anemones and a whole lot more. I have also been involved throughout with the wonderful work of the Bahamas Marine Mammal Research Organisation (BMMRO), and have been a part of team since 2017. Abaco is lucky enough to have the HQ at Sandy Point, but we must keep in mind that the organisation’s remit extends throughout the entire Bahamas archipelago, and has firm links with research and conservation organisations on the other islands.

Sperm Whale baby (neonate) Abaco Bahamas (Charlotte Dunn / BMMRO)

The clear turquoise waters around the islands and their cays are well-known to, and appreciated by, all. This is the playground of the smaller marine mammals – the dolphins, smaller whales and the (now a significant presence) manatees.

Less well known are the denizens of the deeper waters and the immense depths of the GREAT BAHAMA CANYON of the northern Bahamas. This is the realm of the large marine animals, from the mysterious speciality beaked whales right up to massive sperm whales.

About 3 weeks ago, the BMMRO research team encountered something truly wondrous off the south Abaco coastline – something to quicken the pulse and gladden the heart – a newborn sperm whale investigating the underwater world it has just been born into. Hopefully it will flourish and live for decades. The hope is sadly tempered by the overwhelming – and increasing – evidence of the terrible effect that humans have caused in just one generation by the pollution of air, land and sea.

Charlotte Dunn posted the footage of 2 separate sightings. Her first caption reads:

“Close encounter with a curious newborn (‘neonate’) sperm whale yesterday – reminding us of the importance of our Shared Waters project about the effects of ship traffic on resident sperm whales, http://www.bahamaswhales.org/research.aspx. The young individuals like this one will be the most impacted if we don’t make serious conservation changes. As this young whale matures, the policy changes we make in the Bahamas now will affect its survival”.

“While their mothers are feeding at depth (knocking sound in the background) this newborn is being cared for by a slightly older calf until the adults return.”

After the second encounter, Charlotte wrote: “Here’s another amazing short clip of the neonate sperm whale we videoed off south Abaco two weeks ago – thank you to the BEP Foundation and the Devereux Ocean Foundation for funding some of our important work with sperm whales in the Bahamas”.

On Charlotte’s conservation points above, over the last 3 months or so I have been checking daily for posts and articles specifically related to stranded, dead, and killed whales, and their stomach contents as revealed by necropsies. I have collected images from around the world. I won’t wreck this marvellous find in Abaco waters by including any of these. This casual research reveals a horrifying attrition rate for marine mammals. Most animals were full of plastics, from micro through flip-flops all the way up to very large chunks. Some of this junk clearly was the actual cause of death rather than a contributing factor. A whale may take several weeks to die in this way. All of it is entirely the responsibility of mankind – and pretty much caused in the last 50 years.

So let’s enjoy this little sperm whale, and hope it grows to an adulthood that will have seen a radical change for the better in its birth environment – the one that should never have been considered ours to destroy.

CREDITS: Brilliant close-up footage plus the clips I have taken from it – Charlotte Dunn / Diane Claridge / BMMRO.

DONATE: If you are touched by the magic of this little Bahamas sperm whale, may I invite you to consider making a donation to BMMRO for its research and conservation work – a scientific commitment that reaches far beyond the waters of the Bahamas. The system is set up to process donations from just $10 upwards, and every cent is used to further the work of BMMRO. Please click the logo below to reach the right page directly.

Sperm Whale baby (neonate) Abaco Bahamas (Charlotte Dunn / BMMRO)

Baby sperm whale off south Abaco, Bahamas ©BMMRO

DOLPHINS IN THE SEA OF ABACO: PLAYTIME

June 24, 2019 by Rolling Harbour

DOLPHINS IN THE SEA OF ABACO: PLAYTIME

Earlier this year, the team at Friends of the Environment in Marsh Harbour Abaco, in conjunction with BMMRO (Bahamas Marine Mammal Research Organisation), arranged a fundraising trip to look for whales and dolphins. On both counts, the guests’ hopes and expectations were amply fulfilled – in fact, almost certainly exceeded.

Where there is a single dolphin, there will almost invariably be others – and so it proved. The group of bottlenose dolphins turned out to be in a very playful mode, living up to their reputation as delightful, inquisitive, entertainers.

One of the dolphins turned out to be a young 3rd generation animal from the same family, recently weaned. The BMMRO has a large photographic library of dolphins and whales, collected over many years. In the photo above, you’ll see that the dorsal fin of the nearest one is ragged, especially near the top. This is the primary method by which individual animals are recorded to assist with subsequent identification in the field (= water) or back at base in Sandy Point by means of the photo archive.

The trip was perfected when a young female sperm whale came close to the boat… and then rolled onto her side, flipper up, to get a good look at the boat and its human contents. A wonderful experience for all those on board.

Credits: BMMRO / Charlotte Dunn; Friends of the Environment

MEET ARNOLD: BE A BAHAMAS BLACK GROUPER GROUPIE

June 11, 2019 by Rolling Harbour

MEET ARNOLD: BE A BAHAMAS BLACK GROUPER GROUPIE

The Black Grouper, like all its cousins, has the twin disadvantages of being fished for sport and fished for food. As demand for grouper on the menu rises, so does its vulnerability. The species is described as a ‘slow breeder’, so a depleting population has less chance of sustaining numbers. The consequence is an exponentially diminishing stock of the species. The equation is simple: fewer fish means less and less stock replenishment.

Formerly plentiful, these groupers (like other grouper species) have moved from an IUCN listing of ‘Least Concern’ to ‘Near-Threatened’. Whatever effect climate change may be having on the oceans, stock depletion of this noble species also has more direct human causes.

An adult black grouper’s diet consists of small fish and squid. Juveniles feed primarily on crustaceans. However, certain tiny reef fish – blennies and gobies for example – are important to the species as ‘cleaners’. You can read about their significance by clicking CLEANING STATIONS.

The service performed by tiny fish on large ones (not only groupers) is an example of a symbiotic relationship known as ‘mutualism’**, in which both parties benefit (the little fishes get gacky bits of grouper to eat). The cleaners are able to do their work inside the gills and even the mouth of the host without being at risk.

The NASSAU GROUPER has a defined and enforced closed season to help maintain numbers. It will be interesting to see if the same protection is eventually extended to the black grouper and indeed to other grouper species.

** The other two types of symbiotic relationship are commensalism, in which only one species benefits while the other is neither helped nor harmed; and parasitism, where one creature (the parasite) gains, while the other (the host) suffers.

RELATED POSTS

Credits: all photos Melinda Riger of Grand Bahama Scuba

‘TELLIN TIME’ – RISE AND SHINE: ABACO SEASHELLS

June 6, 2019 by Rolling Harbour

‘TELLIN TIME’ – RISE AND SHINE: ABACO SEASHELLS

SUNRISE TELLINS Tellina Radiata

I included these pretty shells, with their striking pink radials, in a much earlier post BEACHCOMBING BIVALVES The ones shown here are larger specimens. Some call them ‘rose-petal shells’. The hinges (muscles) are very delicate, and for many of these shells that wash up on the beach, the two halves have separated naturally.

STs are not uncommon, and I recently found some beauties at Sandy Point. They can grow up to about 7 cms / 2.75 inches, and some of these ones were that length, or very nearly so. I realised after I had taken the photos that I should have used a coin for comparison.

TELLIN: THE TRUTH

The occupant of each of these pretty shells is a type of very small clam. I have completely failed to find a photo of a nude one with its shell removed, but maybe these are never seen at all. The clams live on the sea-floor, often buried in the sand, and with the lid (mostly) shut. Then they die (or their shells are bored into by a predator and they are eaten) and the shells eventually wash up empty on the beach. There’s not much to say about them – they perform no tricks (some shell creatures do, such as backflips) and are believed to have vanilla sex lives (some shell creatures are quite inventive in this department).

Inside Story… not much to tell except (a) still very pretty & (b) possible predator bore-hole top right

WELL, WHAT ELSE IS THERE TO THEM, APART FROM BEING PRETTY & BEACHCOMB-ABLE?

The clams have 5 tiny teeth to chew up their staple diet, which is mainly plant material
These include one ‘strong’ tooth, and one ‘weak’ one, though how someone found it out remains a mystery
Tellins are native to the Caribbean and north as far as Florida.
They live mainly in quite shallow water, but can be found as deep as 60 foot
They have no particular rarity value, and are used for marine-based crafts

PLEASE TRY HARDER TO HOLD MY ATTENTION

You know those lovely tellins you collected during your holiday on Abaco to take home to your loved ones? You may have committed a crime! You did take them, didn’t you? However the general rule – law, even – seems to be “in most countries it is illegal to bring back these shells from holidays”. However, you have been fortunate; the Bahamas has no specific prohibition on the removal of tellin shells, certainly not for personal use.

READER COMMENT: WHOOPS! ALSO, PHEW!

As ever, the very excellent Bahamas Philatelic Bureau has covered seashells along with all the other wildlife / natural history stamp sets they have produced regularly over the years. The sunrise tellin was featured in 1995. You can find more – much more – on my PHILATELY page.

All photos Keith Salvesen / Rolling Harbour; Rhonda Pearce Collection plus Seashells.Org, O/S Linnean Poster, O/S BPB stamp

BAHAMAS TURTLES: BE AWARE BUT DON’T BEWARE

May 23, 2019 by Rolling Harbour

Green Turtle Eye (Melinda Riger / Grand Bahama Scuba)

GREEN TURTLE WATCHING

BAHAMAS TURTLES: BE AWARE BUT DON’T BEWARE

MAY 23 is another one of those ‘species awareness’ days. Somewhere in the world, it seems that every day of the year has a creature to be aware of. As the Sixth Extinction looms (the one we’ve promoted in basically two generations), a state of heightened awareness is where we should all be at.

TURTLES BY ADAM REES / SCUBA WORKS

That’s not an end in itself of course – it’s merely the first step to doing something about the species in question… and beyond that, every species. We’ve screwed up their world for them. Awareness is just a wake-up call to action. Support a cause. Join an organisation or group. Support campaigns. Sign up. Write stuff. Do stuff. Don’t do other stuff. Even wearing a “Save the Great-crested Newt” T-shirt would be better than nothing.

TURTLES BY MELINDA RIGER / GRAND BAHAMA SCUBA

Back to the turtles. I have featured a few great sea turtle photos (none of them mine) to concentrate the mind on today’s special species – one of the most loved and admired of the sea creatures of the Bahamas archipelago. If they go, we humans may not be far behind (but at least we won’t have stomachs full of plastic trash).

TURTLES: HAPPY TOGETHER!

Credits: Melinda Riger, Adam Rees, Virginia Cooper – and to all for their work in revealing the wonderful world beneath the ocean waves

ROCK BEAUTY: BAHAMAS REEF FISH (52)

May 10, 2019 by Rolling Harbour

ROCK BEAUTY: BAHAMAS REEF FISH (52)

I last featured the cheerfully-coloured Rock Beauty Holacanthus tricolor 2 or 3 years back. Time has passed; new photos exist; new people have signed up to follow this eclectic menagerie (thank you both). Time for another look at these beauties, which also happen to be cuties.

Look at the little guy above – posing for Pixar, adorably hoping to star in Part 3 of the Nemo / Dory trilogy

These fish are a small species of angelfish. Seen swimming around the reefs they are unmistakeable, not least because of their bright yellow hi-viz jackets, remarkable blue eyeliner and blue-black lippy.

Rock Beauties look like prime candidates for anyone’s aquarium, but their picky dietary requirements and tendency for aggression make them unsuitable.

They are highly specialised feeders, needing marine sponge in their daily diet. They are also prone to chase their tank-mates and nip them. On balance, they look more fetching nosing about the coral anyway.

WHAT DO JUVENILES LOOK LIKE?

Juvenile rock beauties are cute mini-versions of the adults, only more yellow and with yellow lips. In some development stages, they have a smart blue circle around the dark patch on their sides (bottom image).

NOTE Rock Beauties have no known kinship with Chrissie, Debbie, Lita, Joan, Jennifer, Stevie, Madge and the rest of the accredited ‘Rock Beauties aka Chicks’

NOT A TRUE ‘ROCK BEAUTY’ (no offence, Lita)

A TRUE ROCK BEAUTY

Credits: Melinda Riger, Grand Bahama Scuba; WP

FLAMINGO TONGUE SNAILS: DECORATIVE CORAL-DWELLERS

April 25, 2019 by Rolling Harbour

FLAMINGO TONGUE SNAILS: DECORATIVE CORAL-DWELLERS

FLAMINGO TONGUE SNAILS Cyphoma gibbous are small marine gastropod molluscs related to cowries. The living animal is brightly coloured and strikingly patterned, but that colour only exists in the ‘live’ parts – the so-called ‘mantle’. The shell itself is usually pale, and characterised by a thick ridge round the middle. These snails live in the tropical waters of the Caribbean and the wider western Atlantic. Whether alive or dead, they are gratifyingly easy to identify.

Flamingo Tongue Snails (Melinda Rogers, Dive Abaco, Bahamas)

THE IMPORTANCE OF CORAL

Flamingo tongue snails feed by browsing on soft corals. Often, they will leave tracks behind them on the coral stems as they forage (see image below). But corals are not only food – they provide the ideal sites for the creature’s breeding cycle.

Adult females attach eggs to coral which they have recently fed upon. About 10 days later, the larvae hatch. They eventually settle onto other gorgonian corals such as Sea Fans. Juveniles tend to live on the underside of coral branches, while adults are far more visible and mobile. Where the snail leaves a feeding scar, the corals can regrow the polyps, and therefore the snail’s feeding preference is generally not harmful to the coral.

The principal purpose of the patterned mantle of tissue over the shell is to act as the creature’s breathing apparatus. The tissue absorbs oxygen and releases carbon dioxide. As it has been (unkindly?) described, the mantle is “basically their lungs, stretched out over their rather boring-looking shell”.

THREATS AND DEFENCE

The species, once common, is becoming rarer. The natural predators include hogfish, pufferfish and spiny lobsters, though the spotted mantle provides some defence by being rather unpalatable. Gorgonian corals contain natural toxins, and instead of secreting these after feeding, the snail stores them. This supplements the defence provided by its APOSEMATIC COLORATION, the vivid colour and /or pattern warning sign to predators found in many animal species.

MANKIND’S CONTRIBUTION

It comes as little surprise to learn that man is now considered to be the greatest menace to these little creatures, and the reason for their significant decline in numbers. The threat comes from snorkelers and divers who mistakenly / ignorantly think that the colour of the mantle is the actual shell of the animal, collect up a whole bunch from the reef, and in due course are left with… dead snails and “boring-looking shells” (see photos below). Don’t be a collector; be a protector…

The photos below are of nude flamingo tongue shells from the Delphi Club Collection. Until I read the ‘boring-looking shell’ comment, I believed everyone thought they were rather lovely… I did, anyway. You decide!

Image Credits: Melinda Rogers / Dive Abaco; Keith Salvesen / Rolling Harbour

TUNICATES: SESSILE ASEXUAL SEA-SQUIRTS

April 19, 2019 by Rolling Harbour

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.

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

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.

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.

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.

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

‘REEF ENCOUNTER’ 1: GRAY ANGELFISH

April 4, 2019 by Rolling Harbour

‘REEF ENCOUNTER’ 1: GRAY ANGELFISH

Today I learn from a cheery message from WordPress that my illustrated ramblings have been going on for exactly X years, where X is greater than 5 but less than 10. Time to start a new theme: channelling my inner Noel Coward, I am introducing a new mainly pictorial series provisionally called ‘Reef Encounter’. All the awesome beauty of reef life will be here.

In the past I have posted about GRAY ANGELFISH, one of three kinds of angelfish found in the northern Bahamas. Today, I am featuring some more recent images of these pretty creatures. Note in particular the striking shape and colour of their mouths, the blue being found also on the fin edges at the back.

On this otherwise gray fish, you’ll also find touches of yellow on the face and the edges of the front fins. In the header image there’s another little fish in the bottom right corner. Not a baby angelfish, but a FOUR-EYED BUTTERFLYFISH – a species that will feature in own right in due course

All fabulous photos by Melinda Riger / Grand Bahama Scuba

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

March 7, 2019 by Rolling Harbour

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

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.

At the moment it can still be said that the static (‘sessile’) members of the Abaco reef community are relatively unscathed by the impact of (and I don’t want to get into any arguments here) whatever causes mass bleaching and the death of reefs elsewhere in the world.

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.

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.

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

One species impervious to this deterrent is the fascinating FLAMINGO TONGUE SNAIL (more of which quite soon). Other ‘safe’ species include the fireworm and BUTTERFLYFISHES.

One benefit of sea fans to mankind is that their defensive chemicals have been discovered to provide the basis for drug research and development. It’s tempting to say that by way of gratitude, we pollute the waters they need for their very existence. So, consider it said…

All the photos featured are by courtesy of Capt. Keith and Melinda Rogers of the well-known local scuba dive and snorkel centre DIVE ABACO, located in central Marsh Harbour. As prime enablers of reef exploration in Abaco waters, it can truly be said that they too have plenty of fans.

Credits: Keith and Melinda Rodgers; Dive Abaco @DiveAbaco, Marsh Harbour, The Bahamas ** The answer to the questions in the Title is… it’s both!

PILOT WHALES: “DIVIDED BY A COMMON SEA”

February 25, 2019 by Rolling Harbour

PILOT WHALES: “DIVIDED BY A COMMON SEA”

You know the thing about Britain and the US being ‘two Nations divided by a common language’? Among the many august people credited with first coming up with this remark, the leading contenders are Oscar Wilde, George Bernard Shaw and Winston Churchill. Generally, Wilde seems to be considered the winning author**. Whichever, the saying is intended to be lightly and amusingly rude, probably to both nations.

Well, pilot whales are in a similar position. They are found on both sides of the Atlantic (and many other places of course). As acoustic analysis of the sounds made by marine mammals becomes increasingly sophisticated, the evidence suggests that a pilot whale in The Canary Islands saying “Hey guys, meal approaching 11.00 o’clock, moving right, 30 feet” will use different sounds from its counterpart in the Bahamas.

A pilot whale with a recent injury to its jaw. Chief suspect: a COOKIECUTTER SHARK?

Short-finned pilot whales (Globicephala macrorynchus) are also known as blackfish or potheads (though some may reserve this last term for – ahem – higher species). As with MELON-HEADED WHALES, they are in fact a species of large dolphin. They can grow to nearly 20′ long and weigh accordingly.

Pilot whales live in large pods of 50 or more. These are so-called ‘matrilineal’ groups, meaning that they consist of 2 or even 3 generations of related females. When the sea is calm, they sometimes adopt a behaviour known as ‘logging’, in which they will spend a long time – maybe hours – lying on the surface in tight groups.

In The Bahamas, pilot whales are seen year-round but are more common during the spring and summer months. Some are resident, but Bahama pilot whales appear to have large ranging patterns. Pilot whales tagged in The Bahamas have travelled as far north as North Carolina suggesting they are part of a population located in the US southeast .

HOW DO RESEARCHERS RECOGNISE EACH ANIMAL?

The first place to look is the dorsal fin. There are (at least) two reasons for this. First, it’s the part of the dolphin / whale that is most visible through binoculars; secondly, it is the part that tends to acquire nicks, ragged edges, and scar patterns that are unique to that animal. When a new cetacean is sighted, it is logged and assigned an ID. This will usually be kept simple and scientific: “look, there’s AL16 again” and so on; how unlike birds, where banders assign names such as Felicia Fancybottom, Bahama Mama and Harry Potter.

If you look at #2 above, notice the distinctive hooked dorsal fin of the right-hand pilot of the trio. An easy ID for future sightings. And see below for nicks and scarring.

MEANWHILE, 3643 MILES EAST ACROSS THE ATLANTIC

Last Autumn my niece and her family went to La Gomera, a small volcanic island in the Canaries. They all went on a whale / dolphin watching trip and were delighted to encounter a group of pilot whales. My great nephew, not yet a teenager, had an iphone with him and in the circumstances of standing on a moving platform photographing creatures swimming fast through the water, he did a very good job. A couple of them even have a bonus shearwater.

The west and east Atlantic pilot whales shown here are almost exactly on the same latitude

I’m not particularly bothered by my lack of photographic eptitude, but even I feel that my own shot of a pilot whale in the Sea of Abaco rates high in the list of epic fails

The identity of the photographer is protected under the Official Secrets Act 1989

** ‘We have really everything in common with America nowadays except, of course, language’ Oscar Wilde The Canterville Ghost (1887)

Photo Credits: 1 – 5, BMMRO / Rolling Harbour; 6 – 10, my naturalist nephew Yarin; 11, name withheld by order of the management; 12, Marina Nolte / Wiki. General thanks: Diane, Charlotte, BMMRO

WTF? (WHAT’S THAT FISH?) 17: YELLOWHEAD JAWFISH

February 7, 2019 by Rolling Harbour

WTF? (WHAT’S THAT FISH?) 17: YELLOWHEAD JAWFISH

It’s been a little time since I added to the WTF? series, in which some of the more outlandish reef denizens come under close scrutiny. Jawfishes (Opistognathidae) come into this category, not least because of their interesting ways with their eggs. Also, they tend to stick upright out of the substrate, which is not especially fishy behaviour.

More than 50 species of jawfish are found around the world. In the Bahamas, you are most likely to encounter the Yellowhead (or Yellow-headed) variety. And if you think they look slightly… primitive, that’s because they are. In fact, their forebears (forefishes?) originated in prehistoric times, specifically the Miocene era (a lot of million years ago, I didn’t count exactly).

These rather extraordinary little fish superficially resemble certain types of BLENNY. Their modus operandi is to burrow down into sandy, gravelly or other loose substrate. They do so by cramming their mouths with sand and spitting it out to one side. By this means they form a tunnel of sorts in which they can live, and from which they can emerge, or half-emerge and take a look around them. As they do so, they hoover up passing food, mostly plankton and suchlike.

If something looks threatening while they are feeding or having a look around, they can simply duck down into their burrow for safety. They guard their patch against rivals, and behave ‘territorially’ in the jawfish community. One method is to ingest and and then eject sand or gravel at a would-be intruder.

YES, BUT WHERE IS THE REAL ‘WTF?’ FACTOR HERE?

Good question. With a good and original answer. These little creatures are so-called ‘MOUTHBROODERS‘, meaning that they carry their eggs in their mouths. Depending on the species, females, males or even both parents (don’t try this at home) will do this at or after fertilisation. In effect the eggs are safely incubated until they hatch as fry. Then they are on their own.

ARE THERE ANY DRAWBACKS TO THIS UNUSUAL GESTATION METHOD?

Apart from accidentally swallowing the occasional potential junior, the eggs need aeration from time to time. This is achieved by expelling the eggs from the mouth, and quickly sucking them back in again. Try this very short video to see this rather improbable behaviour in action. It’s only 8 seconds blink and you’ll miss the action. The eggs hatch into fry in 8 – 10 days, after which both parents can relax. Until the next time.

Yellowhead Jawfish (Melinda Riger / Grand Bahama Scuba)

Photo Credits: all images from Melinda Riger / Grand Bahama Scuba except (4) Virginia Cooper / GBS; (5) Michael Wolf / Wikimedia; video, Alan Keller. Research: magpie picking, not excluding yet not limited to Wiki…

BAHAMAS REEF FISH (51): BLACK MARGATE

January 28, 2019 by Rolling Harbour

BAHAMAS REEF FISH (51): BLACK MARGATE

The black margate (Anisotremus surinamensis) is a type of GRUNT (see also PORKFISH) found among the reefs and rocks of (mostly) the western Atlantic seaboard, from Florida as far south as Brazil. They are relatively ‘shallow’ fish and they prefer to be close to place where they can live safely and avoid the predators that lurk in open or deep water.

Margates are not usually very large, mostly growing to between 18″ and 30″, although they can grow larger. Thanks to the awesomeness of Wiki and other reliable sources I can confidently report that “…the maximum recorded weight for this species is 5.8 kg (13 lb)“.

MAY WE HAVE THE TRADITIONAL 10 FUN FACTS PLEASE?

Local names include burriquete (Sp) and zapatero or burros (Mex)
There are 10 margate species world wide, including 2 Pacific versions
Their heads slope down to a notably thick lipped mouth in which they have strong teeth
Margates have erectile spines, presumably for defence (I’ve not tested that)
They like to shelter in caves and crevices, on ledges, and in wrecks (see pics)
Margates are ‘solitary fish’ or hang out in small groups
They are night-feeders on a diet of crustaceans, mollusks, smaller fish & urchins
Sadly for them, they are valued by commercial fisheries using baited drift fishing…
…and also targeted by anglers during the spawning season when they shoal (?unfair)
… and also caught as aquarium fish, adding to stock depletion

RELATED SPECIES

PORKFISH

Credits: all photos, Melinda Riger / Grand Bahama Scuba; research from magpie pickings and in particular the interesting mexicanfish.com

FORAYS WITH MORAYS (6): WELL SPOTTED…

January 21, 2019 by Rolling Harbour

FORAYS WITH MORAYS (6): WELL SPOTTED…

I was always taught ‘keep your mind open and your mouth closed’. Bad advice. Such bad advice. The worst. So many reasons to be exactly the opposite in these troubled times…

Spotted Moray eels Gymnothorax moringa, however, seem to have their own rules to live by. They appear to be open-minded and fairly sensible creatures around the reef. They tend to keep themselves to themselves, hanging out unassumingly in holes and crevices in the coral.

They do tend to stick their necks out a bit, but unless provoked (see below) they seem to be reasonably amiable (except maybe to the small fish and crustaceans that make up their diet).

They do keep their mouths open a lot, though. And as you can see, they have sharp-looking teeth that you mightn’t want too near to you. I say that because their bite can be dangerous and should be avoided. To start with, the teeth are slightly backward-facing, so that when they bite there is a ‘pull-back’ effect when you react (not unlike a barb on a fish hook). They are not aggressive as such, but they know how to deal with unwanted interference in their lives…

Apart from the unpleasant bite and associated pain that moray eels can inflict in defence, they are also poisonous (as opposed to venomous). Specifically they can release toxins into the wound; and in some species their skin contains toxins as well**. Serious infection may result.

CAN YOU GIVE THE POISONOUS / VENOMOUS DISTINCTION AGAIN

I could, but ace natural history cartoonist Rosemary Mosco makes a better job than I can:

**Before I leave the topic, maybe I ought to mention one bit of research I have just come across at Dove Med, from which I take away the message that you definitely don’t want to annoy a moray eel or get bitten by one. Ever. They are fine and interesting denizens of the reef, to be admired from a respectful distance…

Photo credits: all amazing photos courtesy of Melinda Riger, Grand Bahama Scuba; cute yet educative cartoon by Rosemary Mosco. Check out her website HERE – and birders, she v good on your specialist subject…

HAWKSBILL TURTLES: ENJOY THEM WHILE YOU CAN

January 3, 2019 by Rolling Harbour

HAWKSBILL TURTLES: ENJOY THEM WHILE YOU CAN

Pliny the Elder (CE 23–79) was one of the earliest naturalists, besides being a philosopher, author and military commander. He wrote Naturalis Historia (Natural History), a wide-ranging work that became a model for later scholarly works, including forms of Encyclopedia. And, as he so nearly wrote, ‘si non amas testudines, vacua anima tua est’ (he that loves not sea turtles, has an empty mind)*.

Hawksbill turtle grazing while a French angelfish looks on Hawksbill Turtle with French Angelfish, Bahamas (Melinda Riger / G B Scuba)

There can be few better ways to start the New Year than with some gorgeous Hawksbill Turtles Eretmochelys imbricata, plus a sprinkling of turtle facts to give 2019 a good push into orbit. Fortunately still available in Bahamas waters, the continued existence of Hawksbills is under serious threat. Make the most of your opportunities.

Guesstimates of the world Hawksbill Turtle population suggest that there are 5 main groups in the oceans, with few enough individuals – especially breeding females – to warrant an IUCN listing of the species as critically endangered
I doubt that many will forget that the next IUCN category is… extinct (≠ ‘fun fact’)
The largest Hawksbill colony in the world nests on an island in Queensland Australia
Turtles leave the sea to lay eggs in a hole dug on the beach, before returning to the sea.
The eggs hatch after c60 days… the turtlings emerge and are then on their own
Hawksbills are omnivorous, mainly eating sponges (& immune from sponge toxins)
They also eat sea anemones, mollusks, and jellyfish
Their grazing lifestyle is an important component of a healthy coral reef ecosystem

Though their shells are hard, Hawksbills are prey for sharks, crocodiles, octopuses and “the biggest predator of all, humans“.
Despite international Hawkbill protection and conservation measures, they continue to be illegally hunted – including, in some places, for food.
Their lovely shells – tortoiseshell – are illegally traded for use for ornaments and jewellery
Japan makes its own rules (as with whales) for traditional & no doubt research purposes
‘Tortoiseshell’ is the illegal item most frequently confiscated by custom officials
Reef and beach degradation, development, light pollution (confuses the baby turtles trying to paddle to the sea), ocean pollution / marine debris, and illegal practices are among the greatest dangers to the survival of the species. All are caused, directly or indirectly, by you and indeed me

Credits: wonderful photos by Melinda Riger / Grand Bahama Scuba (1, 2, 5) & Adam Rees / Scuba Works (3, 4, 6); Widecast; Nature Conservancy; OneKind Planet

* Do not believe this – I invented it. The pretentious quote that props up the other stuff, that is – all the rest is true…

BAHAMAS REEF FISH (50): TOBACCO BASSLET

December 6, 2018 by Rolling Harbour

BAHAMAS REEF FISH (50): TOBACCO BASSLET

Welcome to #50 in the Bahamas Reef Fish series. I chose this fish to honour the landmark before thinking about its features. Grumpy. Also, associated with a narcotic and dangerous drug. And a fish one probably wouldn’t bother to smoke (even if one could get it to light underwater). In the Bahamas you’ll find these little fish around the coral reefs where they play their part as reef denizens, which includes being prey to larger species. If one looks them up online, however, the overwhelming impression from the websites and images available is that they exist largely for the benefit of the aquarium industry.

Tobacco basslets (Serranus tabacarius) – more commonly just called tobacco fish or tobaccofish – are related to the HARLEQUIN BASS(LET), a species that was most unfairly included as #9 in my parallel WTF? series among all the seriously weird sea creatures that feature in that category. A wrong I must right one day.

Tobacco fish are considered to be hardy, unaggressive (except towards the tiny fishes and crustaceans they feed on) but apparently they need quite a large tank to hold them. The ocean might be suitably large for the purpose. Especially as it seems that in an aquarium there needs to be a cover on top: “these fish are expert jumpers…“, as one source puts it…

BESIDES THE BAHAMAS & AQUARIUMS WHERE ELSE DO THEY LIVE?

APART FROM THE HIGH JUMP THING, ANY OTHER TRICKS?

Yes indeed. The Tobacco Basslet is hermaphroditic, like all other members of its genus.

DON’T LEAVE IT AT THAT… HOW DO THEY, YOU KNOW?

I didn’t want you to ask. All their FB pages say “It’s complicated“, but here’s a rough idea…

All individuals start life as simultaneous hermaphrodites (with sex organs of both sexes)
The largest fish lose their female functions and become active sperm-producing males
Each male leads a group of hermaphrodites and protects them from other males
This gives them exclusive rights to the female parts of members of their ‘harem’
Sometimes hermies may use their male bits to join in & release sperm – ‘streaking’
There are rarer mating strategies… Oh heck, please look at the abstract of a scientific paper for details. I had to! And all because you, gentle reader, asked that question.

With some relief, here is very short video. It probably doesn’t accurately show how Tobacco fish might behave on a Bahamian reef. In captivity, from the look of it, they get pushed around by bigger fish. But maybe, if their co-residents are carefully selected, the bonus is that they don’t risk getting eaten.

OPTIONAL MUSICAL INTERLUDE

There are no songs ever that mention tobacco fish or tobacco basslets (though lots involve bass). And more oddly, apart from a couple of old blues songs the only truly mainstream song about tobacco by name (as opposed to content) is Tobacco Road, a song as frequently and thoroughly covered as an aquarium tank containing jumpy tobacco fish.

Rare photos from the actual sea captured by Melinda Riger of Grand Bahama Scuba; Science Direct plus magpie pickings; Captive Aquatic Ecosytems (video)

I didn’t enjoy this article about me very much. I am NOT grumpy. Tobacco Basslet (Serranus tabacarius) Bahamas (Melinda Riger / GB Scuba)

BAHAMAS REEF FISH (49): BANDED BUTTERFLYFISH

November 22, 2018 by Rolling Harbour

BANDED BUTTERFLYFISH – BAHAMAS REEF FISH (49)

The banded butterflyfish (Chaetodon striatus) is one of several butterflyfish species found in Bahamas waters. There are links to some of the others at the end of this post. The reason for the name is obvious. The purpose of the patterning (striatus) is to act as an adaptive anti-predator defence when seen against the varied landscape of the coral reefs that are its home.

These little fish tend to be found either singly or in pairs. Two of them together may play a form of chase game among the corals and anemones of the reef.

Banded butterfishes, like their cousins, have a varied diet that includes small crustaceans, worms, and coral polyps. They also have a valuable role on the reef by acting a cleaner fish for larger species like grunts, tangs and parrot fish. This sort of relationship, where one party benefits from this kind of interaction , is known as ‘commensalism’, one of the 4 types of symbiotic relationship.

RELATED LINKS

LONGSNOUT BUTTERFLYFISH

BUTTERFLYFISHES (RH guide to reef, banded, four-eyed & spotfin)

REEF FISH INDEX gateway to loads of colourful finny species

WHAT’S THAT FISH? A handy resource

FLORENT’S GUIDE A ditto

Credits: Melinda Riger / Grand Bahama Scuba

PURPLE VASE SPONGES: BAHAMAS REEF ORNAMENTS

November 13, 2018 by Rolling Harbour

PURPLE VASE SPONGES: BAHAMAS REEF ORNAMENTS

The Purple Vase is an unmistakeable sponge, a colourful reef creature (for they are animals, of course) that stands even out amongst the bright corals that surround it. And like corals, sponges are vulnerable to all the usual threats (mainly human-generated).

Catch them while you can in the clear waters of the Bahamas while stocks last. I say this because as study after study concludes, the prospects of reef-mageddon get closer each year. When the corals die off, so in all probability will the sponges and anemones…

After such a depressing intro, let’s move on to take a positive look at the purple vase sponge. As with all sponges, once a newborn sponge is wafted by the current to a place on the reef, it takes root there throughout its life. There, these attractive sponges exist by filtering the water that surrounds them, separating out plankton to feed on. Static filter-feeders, if you will.

You’ll notice that in some of the photographs, the sponges have guests. These are BRITTLE STARS, and they are often found on – and indeed in – purple vases. This is a form of symbiotic relationship known as commensalism, in which one species benefits and the other is neither benefitted nor harmed. The brittle star gains a shelter and a safe base for feeding; the vase gets a harmless companion. Small fishes benefit from the vases in a similar way.

Besides the impact of damaging human interventions (which may be permanent), extreme weather events also affect reef life and the static inhabitants adversely. Storms and hurricanes can cause localised havoc, but the damage is not necessarily permanent. The reef can in time repopulate naturally and flourish again. Humans can even promote this recovery. The photograph above shows a purple vase sponge that was detached from the reef by Hurricane Matthew in October 2016. Melinda Riger in effect replanted it on the reef and it reattached itself and grew. In due course it even acquired its brittle star occupant.

*JIMI AND ‘PURPLE VASE’ – A VOLUNTARY MUSICAL DIGRESSION

In an interview with NME Hendrix is reported to have said that Purple Haze “was about a dream I had that I was walking under the sea.” Originally the song was intended to be ‘Purple Vase’, and reflect the psychedelic experience of life on a coral reef. Realising he was getting bogged down by sub-aquatic imagery (he was a non-swimmer), he toked for a while and then ‘Purple Haze’ emerged almost fully formed. He was always far happier kissing the sky than wandering about under the waves. Most covers of the song are pale imitations of the original, but here’s a rather unusual take that succeeds by trying a different approach…

Credits: Melinda Riger / Grand Bahama Scuba for all great photos; magpie pickings for bits and pieces, with a shout-out to ‘Critter Squad’ for its informative site aimed at kids. And amateur grown-ups can benefit too… commensalism in humans; Friend ‘n’ Fellow audio

BAHAMAS REEF FISH (48): SCHOOLMASTER SNAPPER

November 1, 2018 by Rolling Harbour

BAHAMAS REEF FISH (48): SCHOOLMASTER SNAPPER

November 1st already, and the first time I am prepared to consider the possibility of the onset of Christmas, with its attendant joys yet complications… Meanwhile, I thought I might have run out of types of reef fish to feature in this series long before I got to 50. Yet here we are, two short of that target, with a species of snapper I haven’t even mentioned before. I am (frankly) a rather feeble swimmer, and do not possess a viable underwater camera. So there’s no way I could show these denizens of the not-especially-deep without heavy reliance on others, in particular the outstanding photos of diver Melinda Riger of Grand Bahama Scuba; and the memorable ones from Adam Rees of Scuba Works that include some of the more obscure species that appear in my WTF? (What’s That Fish) series.

The schoolmaster snapper (Lutjanus apodus) lives among the coral reefs and mangroves of the Caribbean and further north to the northern Bahamas and Florida. Generally they are quite small, not much more than 12- 18 inches. They tend to hang out in ‘schools’, which several sources suggest as the reason they got their common name. But schoolmasters don’t really move around in large groups, do they? It’s school pupils that do that, but ‘Pupil Snapper’ wouldn’t cut it as a fish name I guess.

10 SCHOOLMASTER SNAPPER FACTS TO PONDER

One pair of upper teeth are so large they protrude when the fish shuts its mouth
Their side scales are so arranged that diamond shapes are produced
There’s plenty to learn about their fin arrangements, but not necessarily to remember
Their jaws don’t open very wide, so their prey tends to be quite small
Unlike fish that change sex as they grow, these ones retain their birth gender for life
When they spawn they produce their gametes simultaneously, and swim away
The fertilised eggs sink to the bottom, where they have to take their chances
Though small, they are good to eat and are fished for recreation and commercially
Regionally there are specific regulations as to catch length & limits, hook type, bait etc
Like all snappers and many other fish species, these fish are associated with ciguatera

RECIPES

For those who enjoy cooking (whatever that is), you probably know exactly how you like to cook your snappers. For anyone else, here’s a site that proposes several different ways to cook them, with helpful tips. These seem to apply to all snapper species, most of which are available free in the Bahamas. http://www.allfishingbuy.com/Fish-Recipes/Snapper-Recepies.htm

My favourite schoolmaster snapper photo of those featured here

POSSIBLE MEDICAL BENEFITS FROM EATING SNAPPERS

These are alleged to include (except when fried): protection against certain types of stroke, reduction of heart arrhythmia, and defence against certain types of cancer. Don’t take my word for it, though. And definitely don’t rely on a snapper-based diet regime. I think the most that can safely be said is that eating snapper will do you no harm (except when fried) and may conceivably have a marginal benefit on health along with a balanced diet, exercise, minimal alcohol intake and all the routines that we strictly adhere to for a healthy life. In our dreams, anyway.