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

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

BOTTLENOSE DOLPHINS IN ABACO WATERS (2): MOTHER & CALF


Dolphin Mother & Calf, Sandy Point, Abaco, Bahamas 12

Sometimes things happen that completely take my breath away. Here is one of those moments, from our recent trip with Charlotte and Diane in the BMMRO research boat. As we returned from whale-watching to base in Sandy Point and moved from the deep dark ocean to the bright blue shallows, we encountered a group of bottlenose dolphins. You can see my recent post featuring some of the adults HERE. That was exciting enough, as they played around the boat. Then another participant appeared… 

 Notice the dark area behind the adult dolphin… Dolphin Mother & Calf, Sandy Point, Abaco, Bahamas

…which soon separated into a small dark splashing creature with its own fin cutting the waves…Dolphin Mother & Calf, Sandy Point, Abaco, Bahamas

…and next seen keeping pace with its parentDolphin Mother & Calf, Sandy Point, Abaco, Bahamas

The sharp line between the light and the dark sea is where the sandy shallows abruptly give way to the deep waters of the Grand Bahama Canyon, a massive trench up to 2.5 miles deep with almost vertical cliff walls to the depths in some places

Dolphin Mother & Calf, Sandy Point, Abaco, Bahamas

Dolphin Mother & Calf, Sandy Point, Abaco, Bahamas

There were less active and splashy moments as the pair swam around togetherDolphin Mother & Calf, Sandy Point, Abaco, BahamasDolphin Mother & Calf, Sandy Point, Abaco, Bahamas

Then it was back to doing what they like best…Dolphin Mother & Calf, Sandy Point, Abaco, BahamasDolphin Mother & Calf, Sandy Point, Abaco, Bahamas

Then some more restful moments…Dolphin Mother & Calf, Sandy Point, Abaco, Bahamas Dolphin Mother & Calf, Sandy Point, Abaco, Bahamas

And finally the pair moved away. On the far horizon, the Massive Mickey Mouse Cruise ship moored at ‘Disney’s Castaway Cay’ (formerly the sober-sounding Gorda Cay), where you can be a Pirate of the Caribbean. Or anyway a very happy Tourist. The choice is yours. Would you like fries with that?Dolphin Mother & Calf, Sandy Point, Abaco, Bahamas

And looking out to sea from the cheerful place that is Castaway Cay, I wonder if a small child was wondering “Ok, love Mickey and his Friends – but I’d also really love to see a wild dolphin swimming free… 

Disney Magic docked next to the Castaway Cay Family Beach copy

All photos RH (except Castaway, Wiki). Huge thanks to Charlotte, Diane and Bahamas Marine Mammal Research Organisation BMMRO for a truly wonderful day photo 2

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BOTTLENOSE DOLPHINS IN ABACO WATERS (PART 1)


Bottlenose Dolphins, Rocky Point, Abaco (Keith Salvesen : BMMRO) 7

BOTTLENOSE DOLPHINS IN ABACO WATERS (PART 1)

DCB GBG Cover Logo dolphin

This seems to be a excellent early Spring for dolphin and whale sightings in Abaco waters. I’ve noticed that people have been posting dolphin sightings on FB recently. In our brief window of opportunity each March, I usually reckon to see 2 or 3 dolphins at most – maybe crossing over to Hope Town on the ferry, or more probably on a fishing trip. This year we saw 2 groups of about 6 off Cherokee while fishing, including calves. On another day, 4 adults made a leisurely progress the whole length of Rolling Harbour while we watched from the balcony of the Delphi Club. I don’t think they have ever been so close to the shore there before. The best was to come.Bottlenose Dolphins, Rocky Point, Abaco (Keith Salvesen : BMMRO) 3

Near the end of our trip Charlotte Dunn and Diane Claridge invited us to go out with them on the BMMRO research boat. This is equipped with a hydrophonic system that can detect the bleeps, whistles and clicks of cetaceans, and record them for comparison with previous data. This enables particular animals to be identified from their vocalisations. The other method is to note particular features of an animal – damage to a fin, markings on the flank and so on. During the day C & D happily conversed in code: “Is that 132 over there?” “No, it’s got a nick in the fluke, it must be 127…”BMMRO Research Boat, Sandy Point, Abaco

As we returned in the RHIB from an amazing day spent at close quarters with beaked whales [more on these soon], we moved from deep dark blue ocean to sandy turquoise shallows. There, just off Rocky Point (near BMMRO HQ at Sandy Point) were half a dozen bottlenose dolphins, including a mother and calf. This post contains a small batch of photos of adults – there’ll be another post shortly featuring the calf… Bottlenose Dolphins, Rocky Point, Abaco (Keith Salvesen : BMMRO) 4Bottlenose Dolphins, Rocky Point, Abaco (Keith Salvesen : BMMRO) 1Bottlenose Dolphins, Rocky Point, Abaco (Keith Salvesen : BMMRO) 5

Here’s a taster for the next post – the calf, just visible close alongside its mother, was being given leaping practice. Watch this blog…

Bottlenose Dolphins, Rocky Point, Abaco (Keith Salvesen : BMMRO) 6

All photos RH. Huge thanks to Charlotte, Diane and Bahamas Marine Mammal Research Organisation BMMRO for a truly wonderful day (and for my cool sweatshirt!) photo 2

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SAW FISH IN THE ABACO MARLS? NO SURPRISE. SAW A SAWFISH? AWESOME!


Pristis_pectinata _Georgia_Aquarium_ Diliff Wiki

SAW FISH IN THE ABACO MARLS? NO SURPRISE. SAW A SAWFISH? AWESOME!

Exactly a year ago, an extraordinary find was made out on the Abaco Marls. Almost disguised against the pale mud under the low water was the first sawfish reported for the Marls. This fish is not merely a rarity in the Northern Bahamas: all species of sawfishes worldwide are IUCN listed as Endangered or Critically Endangered.

Sawfish, Abaco Marls Feb 2014 (Photo: Jacque Cannon)

Sawfish, Abaco Marls Feb 2014 (Photo: Jacque Cannon)

Here is an account of the discovery reported by FRIENDS OF THE ENVIRONMENT: “On a recent fishing trip in the Marls with local guide Justin Sands, Sam and Jacque Cannon had an exciting encounter. As Justin was poling the flats, with Sam on the bow searching for bonefish, Jacque spotted a Sawfish! Jacque and Justin quickly forgot about Sam and his efforts to catch a bonefish and turned their focus to the Sawfish. This is a very rare sighting and one we are happy there was a camera available to document it…” A couple of weeks later I was lucky enough to sit next to Jacque at dinner at the Delphi Club, so I was able to hear at first hand the story of this amazing find. It also turned out to be the perfect time to sign an early copy of “The Birds of Abaco” for Jacque and Sam… 1900063_10152069487394482_984358031_n

Sawfish Book Plate (1884)

Sawfish Book Plate (1884)

 10 ESSENTIAL SAWFISH FACTS

  • Sawfishes are also known as Carpenter Sharks; their ‘saw’ is called a ROSTRUM
  • There are 7 species in oceans and seas worldwide, including the Mediterranean
  • All populations have declined drastically due to habitat loss, overfishing & pollution
  • The rostrum is used to feel, to dig, to slash & impale or stun its prey, and for defence
  • Sawfishes are nocturnal creatures and spend a lot of time face down on the sea floor
  • Like sharks, their skeleton is made of cartilage and not bone.
  • Some species can grow up to 7m long
  • They are generally unaggressive unless provoked but fight strongly when caught
  • Sawfishes are slow breeders, making population recovery more difficult
  • Babies are called ‘pups’. Their rostrum is flexible and sheathed until after birth
Sawfish seen from Underwater Tunnel - Atlantis, Nassau Bahamas (Fred Hsu)

Sawfish seen from below – Atlantis, Nassau, Bahamas (Fred Hsu)

Other sawfish have been seen recently in the Northern Bahamas, though not in Abaco waters. Last summer the Bahamas National Trust posted 2 great images of a Smalltooth Sawfish, saying “BNT was excited to receive these photographs of a Smalltooth Sawfish photographed in the proposed East Grand Bahama National Park – Bersus Cay Area. The sawfish was 12 to 13 feet long and was seen in water that was 2 -3 feet deep. Thank you to Buzz Cox, Island Manager at Deep water Cay for sending us these photos”. Sawfish, Grand Bahama Sawfish, Grand Bahama

CONSERVATION ISSUES

POPULATION DECLINE As noted above, Sawfish populations have declined to less than 10% of historical levels. The Smalltooth Sawfish – seen above – was once prolific in the Atlantic, Gulf of Mexico, Mediterranean, Black Sea and Indo-Pacific. Population numbers of this species are now estimated at less than 5% to perhaps as low as 1% of their historic levels.

THREAT TO SURVIVAL The threats to their existence are many: habitat loss, overfishing, accidental bycatch, rostrum souvenir hunters (good prices can be obtained), taking them for fins (as a delicacy) or oil from their liver (medicinal).

LEGAL PROTECTION Capturing a sawfish is illegal in certain countries, including the United States. The sale of smalltooth sawfish rostra is prohibited in the United States under the Endangered Species Act.  The import for sale of that of any sawfish species is also prohibited. The international trade of sawfish was banned by the CITES convention in June 2007.
For those that want to find out  a bit more detail about these issues, there’s plenty on interesting information in a scientific (but readable) paper from NOAA – click the link below

A very recent Bahamas smalltooth sawfish sighting on Bimini – Jan 2015Pristis_pectinata_(smalltooth_sawfish)_(Bimini,_western_Bahamas) Lee & Mary Ellen St John Jan 2015 Wiki

Smalltooth Sawfish (Pristis pectinata) Bimini, Bahamas – Lee & Mary Ellen St John Jan 2015

Time for some footage of these rare and wonderful creatures in the Bahamas. The first is from John Flanagan and was taken during a dive off Bimini in early 2014. He was so surprised by the sight that he nearly forgot to turn on his camera to take a short video… The second is a longer 5 min video taken off Andros by Grant Johnson of “wild footage of the critically endangered Smalltooth Sawfish (Pristis pectinata). The west side of Andros, Bahamas is one of the last places on Earth that still provides vast refuge for this incredible animal”.

Finally, you may be wondering how exactly the sawfish uses its rostrum to stun fish, as mentioned earlier. Watch this short video – see how quickly it moves, for such an apparently cumbersome and dozy creature…
Credits as shown above, with particular mention of Jacque Cannon for probably the first known sighting and anyway photo of an Abaco sawfish…; header pic in aquarium Diliff (Wiki)

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

MAKING A SPLASH: SPERM WHALES & MANATEES IN ABACO WATERS


Sperm Whale, Abaco Bahamas (BMMRO)

MAKING A SPLASH: SPERM WHALES & MANATEES IN ABACO WATERS

After a quiet spell on the cetacean and sirenian front, there is exciting news to report. First, the BMMRO encountered two sperm whales just off Sandy Point.  I don’t know how close to the shore they actually were, but it was very friendly of them to come so near to the BMMRO HQ.Sperm Whale, Sandy Point, Abaco BMMRO3

When whales are sighted from the research vessel, one of the tasks is to collect feces. This job is often undertaken by interns, and is a good way to learn that serious research may well involve unattractive work… They practise with… er… coffee grounds and a net. For more on this important yet unappealing aspect of whale research, CLICK NICE TO SEE FAMILIAR FECES. Another essential part of any sighting is to take fluke photos to enable ID.  Every whale has different and distinctive patterning to the fluke, including general wear and tear. As a photo archive is built up, the researchers are able to recognise a particular whale and cross-reference it with previous sightings.

Sperm Whale, Sandy Point, Abaco BMMRO2Sperm Whale, Sandy Point, Abaco BMMRO1

The third task of a sighting is to record clicks made by an individual whale. This enables an estimate of the whale’s size to be made, and again a sound archive is gradually built up from which comparisons can be made.

Sperm Whale, Sandy Point, Abaco BMMRO4

A NEW MANATEE VISITS MARSH HABOUR

FRIENDS OF THE ENVIRONMENT has just reported the sighting of a new manatee at the head of Marsh Harbour harbour. I’m not aware of any other sightings in the last couple of days, but as they say,  “Please keep your eyes out and drive carefully! Contact Bahamas Marine Mammal Research Organization with any further sighting reports by calling 357-6666. You can also share photos with them on Facebook. Also, please do not feed the manatee. They are able to find their own food and anything else may make them unhealthy”.

This is Abaco’s third recent manatee. First there was GEORGIE, who as far as I know is still comfortably settled in the Cherokee area. Then RANDY arrived earlier this and got to within about a few miles of Georgie… High hopes of a meeting – and ‘friendship, maybe more’ – were dashed when Randy turned round and headed back to Castaway Cay. Let’s hope this newcomer stays around. I wonder what he – or she – will be named? My suggestion is Abby or Abi, which I think is unisex…

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Just as with the whale flukes, the tail of a manatee is an important means of identification. The new manatee’s tail has its own distinctive edge pattern, which will enable its future recognition. Here is an image of Randy’s tail, with its unique notch. 

Randy the Abaco Manatee - tail notch

Credits: BMMRO & FOTE with thanks as ever for use permissions

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