PEACOCK FLOUNDER: BAHAMAS REEF FISH (21)


  Peacock Flounder ©Melinda Riger @ GB Scuba

PEACOCK FLOUNDER: BAHAMAS REEF FISH (21)

PEACOCK FLOUNDER or PLATE FISH Bothus lunatus

I have briefly featured this fish before in the context of its extraordinary camouflage abilities; and also its interesting ocular arrangements. Time to give it another swim around, I think, with some additional photos that I have collected.

Peacock Flounder

Bothus lunatus is the Atlantic / Caribbean version of a species also found in the Pacific and Indian oceans. Adults may grow up to 18 inches long. The species is a ‘lefteye’ flounder, with both eyes on its left (top) side & its right side underneath.  However a baby flounder looks & swims like normal fish, with bilateral eyes. As it grows, the right eye gradually ‘moves’ round to the topside, and it becomes a flatfish.

Peacock Flounder

A flounder’s eyes can move independently of each other. One may look forwards, the other backwardsPeacock Flounder Eye ©Melinda Riger @ G B Scuba

‘NOW YOU SEE IT…’ CAMO-FISH

The Peacock Flounder has extraordinary  colour-changing powers, and can rapidly vary its background colour to make it closely resemble that of its surroundings. This enables it camouflage itself as it lies on the seabed. It can change coloration completely in between two to eight seconds.  

Four frames of the same fish taken a few minutes apart showing the ability of flounders to change colors to match the surroundings (Wiki)Peacock Flounder Brocken Inaglory

Check out these imitative patterns in Bahamas waters…Peacock Flounder (f) ©Melinda Riger @ Grand Bahama Scuba

Flower_flounder_in_Kona_wiki

There are two advantages to the ability to camouflage (‘cryptic coloration). One is obviously to avoid detection by predators. The other is to enable the flounder to ambush its meals. They feed primarily on small fishes, crabs and shrimps, lying concealed on the seabed and grabbing any unwary prey that ventures too close. They will even partially bury themselves in the sand, leaving just their eye-stalks keeping watch…Peacock Flounder ©Melinda Riger @ Grand Bahama Scuba

HOW CAN THEY POSSIBLY CHANGE COLOUR SO QUICKLY?

Scientists are still puzzling this out. In a conch shell, it seems the flounder can coordinate its amazing all-round vision with its hormones, instantly releasing certain pigments to its skin cells and suppressing other pigments to make the colour match. Not convinced? Then watch this short video and prepare to be impressed. 

Fred Riger of Grand Bahama Scuba, who kindly keeps a benign eye on my reef fish posts (he’s the expert), adds a third excellent reason for coloration changes: sex… “the male peacock flounder can, and does greatly intensify his colors, presumably to declare territory and attract females to his person. When doing this the males will also signal with the left pectoral fin, sticking it straight up and waving it around.” Maybe that is what is going on in the photo below – intensified, non-camouflage colours, and a raised fin…Peacock Flounder ©Melinda Riger@ G B Scuba

Peacock Flounder on a plate – Kim Rody Art983829_10154948988290716_6633206689277673329_n

Credits: Melinda Riger of Grand Bahama Scuba for almost all photos; wiki for 2 illustrative images

NASSAU GROUPER: VULNERABLE, ENDANGERED… & NOW PROTECTED


Nassau Grouper ©Melinda Riger @ GB Scuba copy

NASSAU GROUPER: VULNERABLE, ENDANGERED… & NOW PROTECTED

The Nassau grouper Epinephelus striatus is one of a number of Caribbean grouper species found generally in the Northern Bahamas and specifically in Abaco waters. Others include the Black, Tiger, and Yellowfin groupers, the Red Hind,and the Graysby. The Nassau grouper is special, however, not least because (unlike the others) it is on the IUCN Red List as an Endangered Species and is also a US National Marine Fisheries Service Species of Concern. It is considered the most important of the groupers for commercial fishing in the Caribbean, and the IUCN listing data suggests that a population decline of 60% occurred over the last three generations (27-30 years), a startling rate. The current population size is estimated at >10,000 mature individuals.

Nassau Grouper ©Melinda Riger @ G B Scuba copy 2

The Nassau Grouper is a creature of the coral reefs in the Caribbean and adjacent seas, though it can also be found in deep water. It feeds in the daytime on small fish and small crustaceans such as shrimps, crabs and lobsters. It lurks in caves and recesses in the reef, sucking in the prey that passes unsuspecting by. The coloration of an individual fish may vary considerably with conditions, and it can adapt its colour to its surroundings as camouflage.  

Tiger grouper meets Nassau grouperNassau & Tiger Grouper ©Melinda Riger @ Grand Bahama Scuba  copy

Spawning takes place in December and January as the seawater cools, always at full moon, and always in the same place. In the moonlight, huge numbers of the grouper gather together to mate in a mass spawning aggregation. This may continue for several days. However, the species is slow breeder, which is why overfishing is particularly damaging to the population as the depleted stock cannot readily be replaced.

3846_aquaimages Wiki

CONSERVATION ISSUES

There are other besides factors commercial overfishing that make the Nassau grouper so vulnerable, including fishing during the breeding season; taking undersized fish; pollution and reef decline; habitat loss; and invasive species. The spawning areas are especially vulnerable to exploitation. In the Bahamas, as elsewhere,  the government has now instituted a closed fishing season for the Nassau grouper. Here is the BREEF  flyer, just circulated – and in fact the reason for this post, which reminded me that I had planned to write about this fish! 10382222_10152869346685953_7443797899832698038_o

THREATS

The Bahamas National Trust sums up the multiple threats in this uncompromising way:

Nassau grouper is eaten by barracudas, lizard fish, dolphins, sharks and other large predators of the reef community. But the predators that have the biggest impact on the grouper population are humansPeople are fishing groupers before they can grow to maturity and reproduce. Sex change may also cause a problem. In undisturbed areas there are usually equal numbers of male and females. In heavily fished areas there are often three or more times more females than males. This means many eggs will not be fertilized during spawning. Other threats include, habitat destruction, coral breakage from divers, siltation from construction, runoff from logging and agriculture, dredging, sewage, oil spills and other contaminants that harm coral reefs where Nassau Groupers live.

grouperEpinephelus_striatus_2

There’s an extent to which a country can be judged on its attitude to wildlife from the stamps it chooses to issue. It’s something to do with appreciation and promotion of the country’s natural resources. For example, North Korea rates nil in this respect, with stamps involving scary weaponry, flags, marching and eerily glowing leaders – not a single sparrow to be seen.  By fortunate contrast the Bahamas and its Postal Service score very highly in celebrating the diversity of the wildlife of the islands. The Nassau Grouper was first featured on Bahamas stamps as long ago as 1971, some 25 years before the IUCN Red Listing, and probably before the sharp decline in population numbers had even begun.

bahamas-1971-nassau-grouper-sg-363-fine-used-19448-p

In 2012 the Bahamas Postal Service released ‘a new definitive 16 stamp series’ depicting the marine life of The Bahamas. The Nassau has been promoted from 5c in 1971 to 70c in 2012. That’s inflation for you.

bahamas-marine-life-stamps2

Finally in 2013 BREEF’s 20 years of marine conservation was commemorated with a distinguished and colourful set of 8 stamps, noting in their release: ‘Two of the new stamps feature the Nassau Grouper, a now endangered species that has experienced severe population decline throughout the region… BREEF is well known as an advocate for an annual closed season for the iconic Nassau Grouper during its winter breeding period. The push for the closed season was based on scientific evidence of population collapses throughout the region due to overfishing. BREEF is calling on the government to implement a fixed closed season for the Nassau Grouper in order to protect the species and the fishing industry. The closed season traditionally runs during the spawning season from December 1st until February 28th, to allow the fish to reproduce.  BREEF is calling urgently for the announcement of this year’s Nassau Grouper closed season….’ And so it came to pass… Not only is the Nassau grouper now worth 2 x 65c; it is strictly protected for 3 months during its breeding season. Maybe philately even had a hand in getting somewhere…

BREEF_Comemorative_stamps_PastedGraphic-3

Nassau Grouper (Rick Smit wiki)

Credits: Melinda Riger, Rick Smit, Open Source, BNT, BREEF, Wikimedia, Bahamas Postal Service

‘WTF?’ IN BAHAMAS WATERS (3) : LETTUCE SEA SLUG


Lettuce Sea Slug ©Melinda Riger @ Grand Bahama Scuba copy

  ‘WTF?’ IN BAHAMAS WATERS (3): LETTUCE SEA SLUG

The ‘WTF’ series so far has covered Bahamas reef fish on the bizarre end of the unusual-to-completely-weird appearance spectrum. And it has stood, of course, for ‘What’s That Fish?’. Today, it doesn’t. The feature creature isn’t a fish at all; it looks like a plant; it is in fact a SACOGLOSSAN - specifically the Lettuce Sea Slug Elysia crispata

The head end is on the left…Lettuce Sea Slug ©Melinda Riger @ G B Scuba copy

The name ‘sacoglossan’ literally means ‘sap-sucker’ (the sapsucker bird has a different latin name, however). And the slug’s frilly edges supposedly resemble certain types of curly lettuce. I’ve no idea where the ‘crispata’ comes from, but I am sure it doesn’t relate to crisp lettuce. These are creatures of shallow, clear waters such as the sub-tropical reefs of the Bahamas.

Lettuce_Sea_Slug_LASZLO ILYES

 ‘SOLAR POWERED SLUGS’

This isn’t a technical forum and too much science hurts my head. This species primarily lives off algae. However I give you the word KLEPTOPLASTY to drop into your conversation. In a sentence, algae is eaten but only partially digested; certain elements are stored to produce photosynthesis by which light is converted to energy and the slug can live without food. But baffle your neighbour at dinner, why not, by summarising the process as “chloroplast symbiosis”. Meanwhile, I’m fetching a beer.

Lettuce Sea Slug ©Melinda Riger @ GB Scuba copy

My research suggests that very little is known about the mating behaviour of these slugs. The pair shown below may be exploring the possibilities, or at least trying to work out which end is which. One is easy to tell, but the other? Time to make our excuses and leave…

Elysia_crispata_(Lettuce_Sea_Slug_pair) Nick Hobgood

HOW FAST, EXACTLY, DOES A LETTUCE SEA SLUG MOVE?

This rather beautiful video from ‘CORAL MORPHOLOGIC’ will reveal all. You’ll soon see that progress is very slow. I recommend watching the first 30 seconds and you’ll get the idea. If you choose to persist, you will see the slug sort of turn a corner to the left.

Credits: Melinda @ Grand Bahama Scuba, Laszlo Ilyes, Nick Hobgood, Coral Morphologic, Wiki

WTF? (WHAT’S THAT FISH?) 2: STRANGE BAHAMAS REEF FISH


Scorpionfish Close-up ©Melinda Riger @GBS copy

WTF? (WHAT’S THAT FISH?) 2: STRANGE BAHAMAS REEF FISH

WTF 1 concerned the REMORA, the upside-down looking fish with the trainer-sole sucker on its head with which it attaches itself to sharks and other large undersea creatures. If you’ve ever seen a picture of a shark with one or more grey passengers hitching a ride, those are these.

Remora ©Melinda Riger @ GB Scuba

WTF 2 features some creatures found in the reef waters of the Bahamas that make you wonder just how and why they are as they are. They look unnecessarily complicated, and the design is somewhat outlandish. See what you think of these…

BURRFISH

Burrfish ©Melinda Riger @ G B Scuba

SLIPPER LOBSTER

Slipper Lobster ©Melinda Riger @ GB Scub.

SCORPIONFISH (& header image) camouflaged against coralScorpionfish camouflaged against coral ©Melinda Riger copy

COWFISH

Cowfish ©Melinda Riger @ GB Scuba   Cowfish 2 ©Melinda Riger @ Grand Bahama Scuba copy

TRUNKFISH

Trunkfish ©Melinda Riger @GBS copy 3

PORCUPINE FISH 

“Watch this…”Porcupine Fish (Virginia Cooper via G B Suba)

“Ta Daaaaaa”porcupine-fish

 AIRPLANEFISH*

Airplane remains ©Melinda Riger @ GB Scuba

*Well, it’s really airplane wreckage. Besides a few other planes and a variety of ships that can be explored underwater, there are also two locomotives in Abaco waters that “fell off” a ship while being transported. Now recreate in your mind the subsequent conversation with an insurance company…

APOLOGIES Header image repeated to sort out FB visuals problem that’s driving me nutsScorpionfish Close-up ©Melinda Riger @GBS copy

Credits: Melinda Riger, Grand Bahama Scuba;Virginia Cooper;  itsnature.org

SHELL HOMES: HERMIT CRABS IN THE BAHAMAS


Hermit Crab ©Melinda Riger @ Grand Bahama Scuba

SHELL HOMES: HERMIT CRABS IN THE BAHAMAS

I’m feeling distinctly crabby right now. In a skilled move that would impress the Bahamas utility providers, the UK’s very own much-vaunted BT selected us for the privilege of being unplugged from the grid last week. From the time of reporting the problem, it has taken them 6 days to plug us back in. It’s a little reminder of the far more persistent Abaco experience! No landline, no wifi, no email for almost a week. To begin with, it was a light relief. After nearly a week, not funny anymore. Here are some nice crabs in conchs to celebrate getting back online while reflecting my crabby mood.Hermit Crab ©Melinda Riger @ G B Scuba Hermit Crab ©Melinda Riger @ GB Scuba copy Hermit Crab ©Melinda Riger @ GB ScubaFind out more about Hermit Crabs – in particular crab racing at Delphi and the intricate rules – here: WACKY RACES AT DELPHIHemit Crab, Delphi (Clare Latimer)

Hermit Crab in a conch ©Melinda Riger @ GB Scuba

Photo credits: all undersea shots – Melinda; potential crab race contestant – Clare

‘TREAT WITH PATIENCE…’ – NURSE SHARKS IN THE BAHAMAS


Nurse Shark ©Melinda Riger @ GB Scuba

‘TREAT WITH PATIENCE…’ – NURSE SHARKS IN THE BAHAMAS

The scientific name for the nurse shark sounds like something Bilbo Baggins might have said to summon elves to his rescue: Ginglymostoma cirratum. Actually the name is a mix of Greek and Latin and means “curled, hinged mouth” to describe this shark’s somewhat puckered appearance. The origin of the name “nurse shark” is unclear. It may come from the sucking sound they make when hunting for prey in the sand, which vaguely resembles that of a nursing baby. Or it may derive from an archaic word, nusse, meaning cat shark. The most likely theory though is that the name comes from the Old English word for sea-floor shark: hurse.

Shark ©Melinda Riger @ GB Scuba

Nurse sharks are slow-moving bottom-dwellers and are, for the most part, harmless to humans. However, they can be huge—up to 14 feet (4.3 meters)—and have very strong jaws filled with thousands of tiny, serrated teeth, and will bite defensively if stepped on or bothered by divers who assume they’re docile. [There are recorded instances of injuries caused to divers who have tried to pull nurse sharks by the tail. And serve them right, I say. Treat them with patience – and respect!] 

Nurse_shark_with_remoras Duncan Wright (Sabine's Sunbird)

Notice that the nurse shark in the above photo, and in the header image, is being attended by REMORAS. Click the link to find out more about the strange relationship these ‘weird suckers’ have with larger marine creatures.

Nurse Shark ©Melinda Riger @ G B Scuba

They use their strong jaws to crush and eat shellfish and even coral, but prefer to dine on fish, shrimp, and squid. [And also stingrays, apparently. They have been observed resting on the bottom with their bodies supported on their fins, possibly providing a false shelter for crustaceans which they then ambush and eat.] They are gray-brown and have distinctive tail fins that can be up to one-fourth their total length. Unlike most other sharks, nurses are smooth to the touch. 

Nurse Shark ©Melinda Riger @ Grand Bahama Scuba

Nurse sharks are found in the warm, shallow waters of the western Atlantic and eastern Pacific oceans. They are abundant throughout their range and have no special conservation status, although the closeness of their habit to human activities is putting pressure on the species.

map-nurse-shark-160-20135-cb1321035858

Nurse sharks are nocturnal and will often rest on the sea floor during the day in groups of up to 40 sharks, sometimes piled on top of each other.

Shark, Nurse (young) ©Melinda Riger @ GB Scuba

FAST FACTS

  • Type: Fish 
  • Diet:  Carnivore
  • Size: 7.5 to 9.75 ft (2.2 to 3 m)
  • Weight: 200 to 330 lbs (90 to 150 kg)
  • Size relative to a 6-ft (2-m) man:
Illustration: Shark compared with adult manNurse Shark ©Melinda Riger @ G B Scuba copy

Credits: All photos Melinda Riger, Grand Bahama Scuba; range map and text mostly  NATIONAL GEOGRAPHIC  filled out with other pickings

‘ELEGANTLY WEIRD’ – SPOTTED DRUMFISH JUVENILES: BAHAMAS REEF FISH (20)


‘ELEGANTLY WEIRD’ – SPOTTED DRUMFISH JUVENILES: BAHAMAS REEF FISH 20

I’ve posted before about the rather extraordinary SPOTTED DRUMFISH, one of those reef fish which in juvenile form is very different from the adult. This species was first up in the Bahamas Reef Fish series – click above link. Here are a few recent images, courtesy of Melinda Riger. The first three show the juvenile form (note the piscine photobomb in the first one). The last shows a group of adults hanging out on the reef with (I think) some soldierfish. You can see how the juvenile drumfish becomes the adult, but those little stripy bullet-heads with their two long elegantly trailing appendages differ considerably from the rather solid-looking spotty / stripy adults with their dramatic punko-rockabilly quiffs.

Drumfish (juv) 3 ©Melinda Riger @ Grand Bahama Scuba Drumfish (juv) 4 ©Melinda Riger @ Grand Bahama ScubaDrumfish (juv) 2 ©Melinda Riger @ Grand Bahama Scuba Drumfish ©Melinda Riger @ Grand Bahama Scuba