BLUE CHROMIS: A FLASH OF COLOUR ON THE REEF


BLUE CHROMIS: A FLASH OF COLOUR ON THE REEF

I’ve gone pictorial for today because I have only got my phone with me while we are away. Composition is slow, close to decomposition – and the comms connection is close to disconnection

Blue chromis (Chromis cyaneus) belong to the same group of fishes 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, and for humans to keep in their own home environments, unselfishly feeding them concocted food.

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”. 

If you are 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).

Credits: Melinda Rodgers / Dive Abaco; Melinda Riger / G B Scuba

PEACOCK FLOUNDERS REVISITED: NOW YOU SEE THEM…


Peacock Flounder (Melinda Riger / G B Scuba)

        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. 

Peacock Flounder (Melinda Riger / G B Scuba)

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.

Peacock Flounder (Melinda Rogers / Dive Abaco)

As the fish matures, in some magic way the mechanics of which I can only guess at**, the right eye grows round to the topside and the flounder transforms from a ‘vertical’ fish to a flatfish. For this reason, the PF is known as a ‘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.

Peacock Flounder (Virginia Cooper / G B Scuba)

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

Peacock Flounder (Melinda Rogers / Dive Abaco)

DO THEY HAVE ANY OTHER TRICKS WE SHOULD KNOW ABOUT?

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

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

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

Peacock Flounder (Melinda Rogers / Dive Abaco)

HOW DO THEY MANAGE TO CHANGE COLOUR IN SECONDS?

It’s complicated! A simple answer is: a mix of hormones, pigment-cells and vision, all coordinating rapidly. The colour change works in two ways: pigments are selectively released to the skin cells; and other 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. 

Peacock Flounder (Melinda Riger / G B Scuba)

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

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

Peacock Flounder (Melinda Riger / G B Scuba)

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

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

**This may in fact 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

Peacock Flounder (Melinda Riger / G B Scuba)

BABY SPERM WHALE IN BAHAMAS WATERS: AMAZING FOOTAGE


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

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. 

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

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”.

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

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.

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

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

MEET ARNOLD: BE A BAHAMAS BLACK GROUPER GROUPIE


Black Grouper, Bahamas (Arnold) - Melinda Riger @ GB Scuba

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.

Black Grouper, Bahamas (Arnold) - Melinda Riger @ GB Scuba

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.

Black Grouper, Bahamas (Arnold) - Melinda Riger @ GB Scuba

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.

Black Grouper, Bahamas (Arnold) - Melinda Riger @ GB Scuba

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.

Black Grouper, Bahamas (Arnold) - Melinda Riger @ GB Scuba

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

TIGER GROUPER

NASSAU GROUPER

RED HIND

GRAYSBY

Credits: all photos Melinda Riger of Grand Bahama Scuba 

Black Grouper, Bahamas (Arnold) - Melinda Riger @ GB Scuba

‘TELLIN TIME’ – RISE AND SHINE: ABACO SEASHELLS


Sunrise Tellin Shell, Abaco Bahamas (Keith Salvesen 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 posBEACHCOMBING 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. 

Sunrise Tellin Shell, Abaco Bahamas (Keith Salvesen Rolling Harbour)

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.

Sunrise Tellin Shell, Abaco Bahamas (Keith Salvesen Rolling Harbour)

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 rightSunrise Tellin Shell, Abaco Bahamas (Keith Salvesen Rolling Harbour)

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

Sunrise Tellin Shell, Abaco Bahamas (Seashells . org)

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!

Sunrise Tellin Shell, Abaco Bahamas (Rhonda Pearce)

 

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.

Sunrise Tellin Shell 5c Stamp Bahamas (BPB)

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

Sunrise Tellin Shell, Abaco Bahamas (Keith Salvesen Rolling Harbour)

ROCK BEAUTY: BAHAMAS REEF FISH (52)


ROCK BEAUTY: BAHAMAS REEF FISH (Melinda Riger / GB Scuba)

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.

ROCK BEAUTY: BAHAMAS REEF FISH (Melinda Riger / GB Scuba)

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

ROCK BEAUTY: BAHAMAS REEF FISH (Melinda Riger / GB Scuba)

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 BEAUTY: BAHAMAS REEF FISH (Melinda Riger / GB Scuba)

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

ROCK BEAUTY: BAHAMAS REEF FISH (Melinda Riger / GB Scuba)

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.

ROCK BEAUTY: BAHAMAS REEF FISH (Melinda Riger / GB Scuba)

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).

ROCK BEAUTY: BAHAMAS REEF FISH (Melinda Riger / GB Scuba)

Rock Beauty, Bahamas (Living Oceans Foundation))

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


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

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.

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

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”

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

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.

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

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…

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

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!

Flamingo Tongue Snail Shell, Keith Salvesen AbacoFlamingo Tongue Snail Shell, Keith Salvesen Abaco

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

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