BRITTLE STARS: PRIMITIVE YET INCREDIBLY COMPLEX STARFISH


Brittle Star around a Tube Sponge ©Melinda Riger @ GB Scuba

BRITTLE STARS: PRIMITIVE YET INCREDIBLY COMPLEX STARFISH

BRITTLE STARS are closely related to starfish, and in particular to Basket Stars. They are commonly known as “serpent stars”, having 5 long, thin arms that may grow as long as 2 feet long. There are lots of different types of brittle star – at least 2000 – and they are found in every ocean on earth from the poles to the tropics. In Bahamian waters they a commonly found living on reefs.

Although these creatures look primitive, their structure, nervous systems, respiratory systems, digestive systems, sex lives and transportation methods are incredibly complex. Take it from me – I’ve just read about it all. So I’ve decided to pick a few aspects of these creatures to highlight rather than discuss the minutiae of their ossicles (tiny bones), madroporites (a sort of water filter / pressure balancer) and viscera.

You are most likely to see Brittle Stars clinging to coral or spongesSponge & Brittle Star ©Melinda Riger @GB Scuba

A DOZEN BRITTLE STAR FACTS TO PLAY WITH

  • The star has no eyes and no sense organs as we know them, but can detect light chemically; and (why would they need this?) sense smell through their ‘feet’… [Not a superpower I would prize, but still]
  • The mouth is on the underside of the central disc (‘body’) of 5 segments, each with a toothed jaw
  • The mouth is used both for ingestion and, putting it delicately, egestion. [Nor that superpower]
  • Stars eat tiny organisms suspended in the water or mini-worms, gathering them with their arms
  • If I have understood this, they breathe through their armpits, and can excrete from here also
  • The arms fit the main part with ball and socket joints, and are flexible in all directions
  • The genitals seem to be located in or between the armpits (lucky we are not descended from stars)
  • Stars readily regenerate lost arms until they lose the 5th – then they are in real trouble
  • This enables them to shed an arm in a predator attack, like a lizard its tail
  • Trials indicate that a jettisoned arm cannot regenerate from itself
  • They use only 4 arms to move along, with the fifth ‘steering’ out in front or trailing behind
  • Brittle Stars are inedible but non-toxic

Brittle Star on Green Rope Sponge ©Melinda Riger @ GB Scuba

Often, brittle stars will cling on inside a spongeBrittle Stars in sponge ©Melinda Riger @ GB Scuba

I quite liked this infographic from a source new to me, ‘Weird ‘n’ Wild Creatures Wikia’Brittle_Stars_front

Here is a great video from Neptune Canada of a brittle star fight on the ocean floor over the remains of a shrimp. If you watch the ones joining the fight, you will clearly see the locomotion method described above, with one limb pathfinding and the other four ‘walking’.

I’m not renowned for extreme sensitivity, so I feel no shame in showing mating brittle stars, courtesy of Channel Banks. It’s not exactly Lady Chatterley and Mellors, but the entwined arms are rather romantic, no?

Credits: all wonderful photos by Melinda Riger of Grand Bahama Scuba; BS infographic and viddys as credited

“ONE IS CALLED LUCY…”: SWIMMING WITH BAHAMAS SHARKS


Shark, Blacktip ©Melinda Riger @ G B Scuba copy 2

“ONE IS CALLED LUCY…”: SWIMMING WITH SHARKS

From time to time I wonder about the naming of animals. I know about the problems that can arise when people name their chickens Henny, Penny, Denny & Lenny, and the time comes to (please look away now). And how a slavering dog coming towards you (not on a lead) that the owner calls ‘Tyson’ or ‘Killer’ is possibly one to cross the street for. And that the owner of a cat called ‘The Reverend Wenceslas Muff’ (Sir Roy Strong, in fact) may not take kindly to you referring to it facetiously as ‘Puddy-tat’. But does it make things any better to know that the shark that is eyeballing you is called Lucy? I don’t know the names of the others, but I am sure they would all like to be introduced… Shark close-up ©Melinda Riger @ G B Scuba copyShark with remora ©Melinda Riger @ G B Scuba copyShark © Melinda Riger @ G B Scuba copy 2Shark ©Melinda Riger @ GB Scuba copy 2Shark Head ©Melinda Riger @ GB Scuba copy 2Shark 2 ©Melinda Riger @ G B Scuba copy 2Shark 4 ©Melinda Riger @ G B Scuba copyShark (pregant female) ©Melinda Riger @G B Scuba copy

REMORAS Some of the photos show a strange creature attached to the underside of the shark. For more info about these weird shark passengers, and some great images, click HERE

All the fabulous photographs above were taken by Melinda Riger and Virginia Cooper of Grand Bahama Scuba, on whom I rely entirely for subaqueous material, being a pathetic swimmer, a gnarly ancient, and a certified scaredy-cat (‘highly commended’). My thanks as always to them for use permission

RED HIND GROUPER: BAHAMAS REEF FISH (25)


Red Hind Grouper Melinda Riger @ G B Scuba copy

RED HIND GROUPER: BAHAMAS REEF FISH (25)

The Red Hind is one of several grouper species commonly found in  Bahamas waters. Commonly for now, anyway. There is less information available about this species compared with other groupers, but sources seem agreed that it is (a) abundant and (b) IUCN listed ‘least concern’ but (c) heavily fished and (d) delicious.

Red Hind, attended by Cleaner FishRed Hind Grouper ©Melinda Riger @ G B Scuba copy 2

Red Hind Grouper ©Melinda Riger GB Scuba copy

One problem arises from the fact that Red Hinds form spawning aggregations in particular areas, making them vulnerable to fishing exploitation in those locations, and consequent population decline. Already, some of their spawning areas are protected.

Another threat comes from the degradation of coastal habitats coupled with increasing commercial and recreational fishing.  Red Hinds are targeted with speargun, hook and line, fish traps and nets. They may also be by-catch of other fishing operations. Fortunately Marine Protected Areas such as the ones in Abaco waters provide localised protection but these are not found throughout the Red Hind’s range. Closed seasons have been imposed in a few areas, another conservation method that has recently been introduced in the Bahamas for the Nassau grouper. 

Female spawning Red Hind Grouper (Univ of Puerto Rico:NOAA)

Getting the right balance between traditional fishing for food, and stock conservation is inevitably a tricky calculation. For the Red Hind, the factors that may result in the population decline of a plentiful species are in plain sight and will continue to be monitored by the various scientific research organisations involved…

OTHER GROUPERS YOU MAY ENJOY…

NASSAU GROUPER

TIGER GROUPER

BLACK GROUPER

Red Hind Grouper ©Melinda Riger @ G B Scuba copy 3

Credits: All images Melinda Riger at Grand Bahama Scuba except (4) NOAA / Puerto Rico Univ; research from several sources, tip of the hat to SCRFA

CHERUBFISH (PYGMY ANGELFISH): BAHAMAS REEF FISH (23)


Cherubfish (Pygmy Angelfish) © Melinda Riger @ G B Scuba

 CHERUBFISH (PYGMY ANGELFISH): BAHAMAS REEF FISH (23)

Time for a bright little denizen of the not-so-deep. The Cherubfish Centropyge argi or pygmy angelfish is a very small (8cm) and distinctively coloured angelfish species. These fish are native to the Caribbean and Gulf of Mexico, and flicker round the coral reefs happily feeding as they go (see the video below to see how busily they forage). Or maybe they are just having a good time…

Cherubfish (rare) ©Melinda Riger @ G B Scuba

The Cherubfish is unsurprisingly a popular aquarium species. Don’t rush straight out and buy some though: a typical warning says “like other angel fish, they are not completely 100% reef-safe. Results vary among individual fish and tank qualities (size, feeding, tankmates, etc.), so caution is recommended when adding this fish to a coral tank“. You can read the whys and the wherefores HERE – sadly I lack the vibrant interest in aquaria to go into it myself…

Cherubfish Melinda Riger @ G B Scuba

Looking beyond Melinda’s lovely images of the species, I have found that these creatures will often show more yellow at the nose end. Here’s an example of a more two-tone Cherubfish in case you come across one. Cherubfish Centropyge argi  (Brian Gratwicke)

I mentioned that Cherubfish flicker around the reefs instead of proceeding serenely and in an orderly fashion.  Have a look at this short video to see what active little fish they are.

RELATED POSTS

GRAY ANGELFISH 1

GRAY ANGELFISH 2

QUEEN ANGELFISH 1

QUEEN ANGELFISH 2

DAMSELFISH

ROCK BEAUTY

Credits: all images Melinda Riger of Grand Bahama Scuba except the last, Brian Glanville

‘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

‘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