A spectacular entry in my WTF? series came courtesy of Adam Rees and a night dive in Florida waters: the guitarfish, (Gr: rhinos – nose; batis – ray) . Until I saw Adam’s photos, this creature was unknown to me. It sounded so improbable, and conjured up some nightmare piscine-based modification of a Strat, an instrument whose classic looks should not be meddled with without consequent loss of liberty.
The guitarfish belongs to a family of rays, Rhinobatidae, of which there are many species worldwide. In some ways the fish looks like a crossover with a shark. Although they have a ‘ray face’ and small wings, there is also a sharklike appearance with its fins and a sharklike swimming action (see video, below). If you think there is a primitive or prehistoric look to the guitarfish, you’d be right. According to the temporal range chart they date from the late Jurassic era.
I have been trying to nail the exact model of Adam’s finny Strat-ray. I am putting my money on the Atlantic guitarfish Rhinobatos lentiginosus, which may (or may not) be the same as the spotted or freckled; and is similar to the more widely photographed shovelnose guitarfish with its cute face. Not that I am very bothered: it’s the overall unusualness of Adam’s creature that really counts.
The strange thing is that although the guitarfish is a denizen of, for example, floridian, caribbean and mexican gulf waters, it is said to be unrecorded for the Bahamas. These bottom-feeding creatures inhabit shallower waters near coastlines and estuaries. They eat crabs, shellfish and worms – all in plentiful supply in Bahamas waters – so I can’t see a reason why they should not be found there. Perhaps they are seen but unreported. I have in mind the recent reports of SAWFISH and BATFISH. So kudos awaits the person who reports – with photo – the ‘first’ Bahamas guitarfish. Maybe there’s scope for a song about it!
GUITARFISH ‘LIVE’
Usually caught by mistake by anglers, or as bycatch by fishing vessels
Inedible (unless someone knows better…)
Non-aggressive and harmless to humans despite having a mouthful of small teeth
Swims like a shark – the tail has no spinal structure
Has a cute face (unlike a a shark)
Adults are about 30 inches long
They may bury themselves in sand or mud to ambush prey
They are viviparous, giving birth to live young that are born fully developed
As a postscript, it’s worth mentioning that on the same night dive, Adam also came across the uncommon batfish, a seriously prickly-looking starfish, and a spotted eagle ray. Worth losing sleep for.
. .
A similar kind of guitarfish, showing the very sharklike movements in the water
Credits: Adam Rees, with many thanks; Greg Hume; Johan Fredriksson wiki; magpie pickings, in particular Florida Museum of Natural History / Taylor Sullivan and the truthful parts of various Wiki articles
The bluehead wrasse (or blue-headed wrasse) Thalassoma bifasciatum is a denizen of the coral reefs in the tropical waters of the western Atlantic Ocean. This bright little 4-inch fish is… a wrasse with a blue head. No more and no less. Unless it’s a juvenile. Then it is mainly bright yellow. It’s similar to BLUE TANG (aka ‘the Disney Dory’), which starts life bright yellow and grows up to be blue.
The species may be found singly, in pairs or small groups, or in schools. They have an important role to play in the life of the reef. They are CLEANER FISH, vital to the health and wellbeing of the larger species they attend to, and thus of the reef itself. This is ‘cleaning symbiosis’, a relationship of mutual benefit. The big fish get cleaned; the little fish have a useful function and – importantly for them – therefore don’t get eaten.
Having said that, blueheads are of course fair game as a snack for species that aren’t in the market for their cleaning services. Rather unfairly, some species that are quite content to let cleaner gobies pick around their gills and mouths are not so considerate of the wrasse (some types of grouper and moray eel, for example).
TELL US EXACTLY SEVEN BLUEHEAD WRASSE FACTS
Juveniles can alter the intensity of their colour, stripes & bars
The bluehead wrasse is a ‘protogynous sequential hermaphrodite’
All are born female**. Some change sex to male during maturation (see below)
Food includes zooplankton, small molluscs and small crustaceans…
…and parasites / other juicy bits (fungal growths, anyone?) from bigger fish
Main threats to the species are coral reef degradation / destruction and pollution
The bright colours invite aquarium use, but the trade in this species is not critical.
** Some sources suggest some are born male and remain male.
A juvenile bluehead – mostly yellow, with a pale underside
THE REMARKABLE SEX LIFE OF THE BLUEHEAD WRASSE
This is an unavoidable topic, I’m afraid. The bluehead’s sex life is the most interesting thing about them, and this is no time to be prudish. It has been the subject of extensive scientific research. As with many human relationships, “it’s complicated” but in a conch shell it boils down to this:
To recap, BWs are born female and as they mature, some become male.
Males reach an ‘initial phase’ when they can breed in groups with females
Some males grow larger & reach full colouration. This is the ‘terminal phase’
These large males aggressively chase away smaller ones & seek females to pair with
Their state of readiness is signalled by colour changes BUT the females know…
…that the smaller males have a sperm count higher than dominant males.
As the excellent organisation OCEANA puts it: Bluehead Wrasses may reproduce in four different ways throughout their lifetime: 1) as a female in a group spawning event; 2) as a female in a pair spawning event within the territory of a large male; 3) as a small male in a group spawning event; and 4) as a dominant, terminal male in a pair spawning event within its own territory.
A cropped still from a video I took at Fowl Cay marine reserve. I’ve looked at dozens of images online and not found one that was all blue with a yellow end to its tail fin. Perhaps it is just an all-blue alpha male.
Credits & Sources: Melinda Riger; Adam Rees; James St John; Oregon State edu / Pinterest; Wiki images; self; Oceana; IUCN; magpie pickings
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.
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
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.
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.
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.
WHY THE UNTIDY MOUTH FURNITURE?
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.
Larger reef fish tend to get more attention than the tiddlers, for obvious reasons. Yet a reef would not properly exist without the small fish that drift and wriggle round the corals. Blue chromis (Chromis cyaneus) are among the first reef fish species I ever met when snorkelling at Fowl Cays.*
Blue chromis belong to the same group as damselfishes. These unmistakeable, bright reef denizens are very visible despite their tiny size. These fish are shoalers, so out on the reef you can enjoy them flickering around you as you swim along or hang in the water to admire the corals.
Like many a pretty and easily captured small fish that can be monetised once removed from its natural home environment, the blue chromis is popular for aquariums. Humans like to keep them in their own home environments safely away from oceans and reefs, unselfishly feeding the little things concocted food to keep their little lives going till the cat gets them. [Sorry, I don’t know what came over me there]
Blue chromis are adaptable and sociable, and will happily swim with other small reef fishes (as above). My own favourite combo is chromis mixed in with sergeant majors. But a shoal of them (mostly) alone is pretty special too….
I cynically mentioned ‘concocted’ food earlier. Here is one online care instruction for looking after them: “They are omnivores, meaning that they eat both meaty and plant based foods. They are not difficult to feed and will eat a variety of regular aquarium fare, frozen, live, and sometimes even dry food. Feeding them a variety of foods will help them retain their color in captivity. They sometimes feed on the algae in the tank”. So I think it’s ok to suggest that leaving the fish out on the reef might suit them better.
If tempted to ‘rescue’ some from their reef habitat, rest assured that they have been known to spawn in captivity. Blue chromis can usually be obtained for about $10-15. And don’t hold back on the frozen food (though maybe warm it up a bit before feeding time). I rest my case.
*I say ‘snorkelling’ rather than anything more impressive because I am a pathetic swimmer and I know my limitations…
Credits: Melinda Rodgers / Dive Abaco; Melinda Riger / G B Scuba
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.
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.
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.
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 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.
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 byKonstantinou, 1994; Miller, et al., 1991in the websiteanimaldiversity.org/…ounts/Bothus_lunatusTo 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 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
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.
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.
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
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)
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. **
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)
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.
** 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 (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.
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.
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 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.
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…”
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.
Credits: all fantastic photos by Melinda Riger of Grand Bahama Scuba; magpie pickings of an unacademic sort for facts and speculation
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.
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.
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.
VULNERABILITY TOCLIMATE 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.
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.
HOW DOES ELKHORN CORAL REPRODUCE?
There are two types of reproduction, which one might call asexual and sexual:
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)
Sexual reproduction occurs once a year in August or September, when coral colonies release millions of gametes by Broadcast Spawning
All photos: Melinda Rogers, with thanks as ever for use permission
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!
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.
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 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 crab…
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 mouth
Spot the esca…
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’.
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 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.“
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.
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 INFOGRAPHICS
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 websiteFROGFISH.CHYou 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
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
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.
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 defence mechanism that protects against potential troublemakers. The main effect is to make themselves unpleasant to nibble or uproot.
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 .
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.
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.
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
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.
“Deck 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).
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
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)
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.
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 WORMS
Credits: Melinda Riger (Grand Bahama Scuba); Nick Hobgood; Betty Wills; Video by ‘Super Sea Monkey’; Reef Collage by RH; MarineBio; Wikibits & Magpie Pickings
HappyChristmas toallthosewho putupwithRHwithsuchfortitude over the years
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’.
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.
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.
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
A Nassau Grouper glumly contemplates the possibility of extinction
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 A CLEANING STATION: PICTURE PERFECT BAHAMAS (5)
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.
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.
A rainbow effect of filtered sunlight on sea fans
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.
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.
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
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.
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
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.
Spot the trumpetfish…
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)
We are back again under the sea, warm below the storm, with an eight-limbed companion in its little hideaway beneath the waves.
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.
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,
The kind of image a Scottish bagpiper should avoid seeing
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
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 inBIOEROSION , a vital process for the health of the reef.
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
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 arePELAGIC 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)
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)
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
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
. 
. 
ROLLING HARBOUR ABACO 
You must be logged in to post a comment.