WATCHING NURSE SHARKS: BE PATIENT…


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WATCHING NURSE SHARKS: BE PATIENT…

I last took a look at nurse sharks nearly 3 years ago HERE. Time to revisit these creatures. Indeed, time for a close-up look. If you want to know more about this fascinating species, just click the link above.

The two strange items hanging down from the upper lip are sensory barbels
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This side-view shows the shark’s relatively small mouth (for a shark anyway)nurse-shark-a-melinda-riger-gb-scuba

Admire the extraordinary texture of the the skin; and the tiny evil eye. Click or – better – double click on the image and you will see that the skin is in fact tessellated, made up of a mosaic of tiny squares and near-squares**nurse-shark-close-up-melinda-riger-g-b-scuba

This one is a baby nurse sharknurse-shark-baby-melinda-riger-gb-scuba

A juvenile nurse shark with a couple of grunts. Note the youngster’s paddle-like finnurse-shark-juv-melinda-riger-g-b-scuba

Head, mouth, jaws and teeth

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SO, THEY ARE SHARKS – ARE THESE GUYS DANGEROUS?

Not really, no. They aren’t looking to pick a fight; and they are not as territorially aggressive as the ‘bitey’ sharks are (or can be).  These slow-moving bottom-dwellers are generally harmless to humans. However, they can be huge—up to 4 metres —and have very strong jaws filled with thousands of tiny, serrated teeth. They will bite defensively if stepped on or bothered by divers who assume they’re docile. [As I said previously, “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 ©Melinda Riger @ G B Scuba copy

**FUN FACT

M.C. ESCHER (the inspiration for Mr Hammer) was the master of tessellation in art. Click the link to explore the dedicated website. Maybe, sensationally, one day a shark will be found with skin like this… (Alert reader: “Actually, I think it most unlikely…”)

Escher fish

Credits: field photos by Melinda Riger, Grand Bahama Scuba; Wiki for the 4 mouth images & the Escher 

Nurse Shark ©Melinda Riger @ Grand Bahama Scuba

CHRISTMAS TREE WORMS: FABULOUSLY FESTIVE


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CHRISTMAS TREE WORMS: FABULOUSLY FESTIVE

music-notes-clip-art-png-music“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 as good time as any to take a look at these remarkable plants creatures and subsurface symbols of good cheer.

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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

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  • 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…

spirobranchus_giganteus_orange_christmas_tree_worm-nick-hobgood-wiki

HOW DO THE WORMS… YOU KNOW…  ER… REPRODUCE?

This is a delicate area. They don’t tend to talk about it much, but as far as I can make out they eject gametes from their what-I-said-above. There are mummy and daddy CTWs, and their respective gametes (eggs and spermatozoa) drift in the current and presumably into each other to complete the union. The fertilised eggs develop into larvae, which settle onto coral and burrow into it, build their protective tubes and the process begins again.

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LOOK, 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). So maybe I should have just posted this first and saved you (and me) some trouble…

The worm, invisible in its coral burrow, hoists its pair of trees. You can easily see small particles – possibly zooplankton – drifting in the water, and the radioles swaying to catch potential food. Bingo. It all makes sense! Next: the New Year Worm

Credits: Melinda Riger (G B Scuba); Adam Rees (Scuba Works); Nick Hobgood; Betty Wills; Absolutely Wild Visuals; MarineBio; Wikibits & Magpie Pickings

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FLORAL CORAL: BEAUTIFUL BAHAMIAN REEF LIFE


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FLORAL CORAL: BEAUTIFUL BAHAMIAN REEF LIFE

This post needs no commentary from me, nor my larky intrusions. These wonderful images from Melinda Riger speak for themselves. You’ll see a wide variety of soft and hard corals in the images below (prize** for the full list). If these superb photos don’t want to make you want to grab a snorkel, mask and flippers, then… well, that would be a very great shame.

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**the prize is the usual legendary bottle of Kalik. Or do I mean mythical?

All wonderful photos by Melinda Riger, Grand Bahama Scuba. All corals also available in a wide range of colours in Abaco waters. See them there on the third largest barrier reef in the world (and in rather better nick that the greatest, by all accounts).

“THE PRINCE OF WHALES”: BLAINVILLE’S BEAKED WHALE


Blainville's Beaked Whale, Sandy Point, Abaco 14 (Keith Salvesen

“THE PRINCE OF WHALES”: BLAINVILLE’S BEAKED WHALE

This post results from a recent Technological Breakdown at Rolling Harbour Towers, and is to be viewed as post-trauma therapy. Smart New Mac ordered, to replace 5 year-old warhorse loosely held together with duct tape and prayer. After lengthy (overnight) data migration, Smart New Mac turns out to be faulty. SNM returned to store: a seething hotbed of stress and distress (the shop too). While replacement is eagerly awaited, fry motherboard of old computer with shorted charger. A week of wailing and gnashing of teeth. Smart New Newest Mac brings you this offering.

I like whales. Everyone likes whales. Even whalers, though for very different reasons. Here are some calming pics of one of Abaco’s largest yet best kept secrets – Blainville’s beaked whales. Adults grow to more than 15 feet long and weigh about 2000 pounds, yet they can behave like huge dolphins in slow motion – circling a boat, diving under it, drifting away, swimming back. They have no motherboard and require no data migration.

The amazing barnacled tusks of a male, that protrude upwards  from the lower jawBlainville's Beaked Whale, Sandy Point, Abaco 16 (Keith Salvesen

Tusks and blowhole…Blainville's Beaked Whale, Sandy Point, Abaco 15 (Keith Salvesen

Dorsal fin damage is an excellent way to ID individual whalesBlainville's Beaked Whale, Sandy Point, Abaco 18 (Keith Salvesen

The knobbly back will help with ID tooIMGP2001 - Version 2

A female beaked whale noses towards the BMMRO research vesselBlainville's Beaked Whales, Abaco (1) (Keith Salvesen)

The beak breaks the surfaceBlainville's Beaked Whales, Abaco (1) (Keith Salvesen)

The blowhole, used for breathing, in close-upBlainville's Beaked Whales, Abaco (1) (Keith Salvesen)

Healed circular wounds caused by COOKIECUTTER SHARKSBlainville's Beaked Whales, Abaco (1) (Keith Salvesen)

‘Dolphining’ towards the RHIB (the small creature between the two on the left is a calf)Blainville's Beaked Whale, Sandy Point, Abaco 8 (Keith Salvesen

CLOSE ENCOUNTER & HEAVY BREATHING

           BMMRO research RHIB                        BMMRO HQ, Sandy Point, AbacoBMMRO Research Boat, Sandy Point, Abaco (Keith Salvesen) BMMRO HQ, Sandy Point, Abaco (Keith Salvesen)

Female beaked whale being peacefulBlainville's Beaked Whales, Abaco (1) (Keith Salvesen)

Credits: all photos & video RH; Charlotte & Diane for a brilliant experience ; Mr Blainville (below) for a brilliant whale

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MANATEE AWARENESS MONTH (& BABY TALK)


Rita the Mantee & her new baby. Bahamas (BMMRO)

MANATEE AWARENESS MONTH (& BABY TALK)

Are you aware of the Bahamas manatees? Just a few years ago your answer might well have been “Bahamas what? No, why? Where?” But suddenly they arrived. And their numbers are increasing. Alternatively, of course, they have always been there, mooching around peacefully and unnoticed in the seagrass. 

Manatee Awareness Graphic (Peppermint Narwhal)

Rita and her recently born daughter – Kamalame, AndrosRita the Mantee & her new baby. Bahamas (BMMRO)

The Bahamas Marine Mammal Research Organisation BMMRO has been keeping tabs on occasional sightings of manatees in Bahamian waters for some years. But until around 2012 – when I first learned of them and wrote about them – they appeared to be few and far between. They seemed to be unrecorded for Abaco, or anyway unphotographed.** Then the sightings began. Names were given to individuals, identified primarily by distinctive marks or cuts on their ‘paddles’ (tails). Gina. Rita. Georgie. Randy. JJ. Sightings in Hope Town, Little Harbour, Cherokee and the Casuarina canal. Manatees had arrived and were being paid attention. The ease of digital photography and the rapidly increasing use of social media resulted in more reports, wider interest and – yes – greater awareness both on Abaco and elsewhere in the wider Bahamas

**so much for being factually assertive! Many thanks to Mary for her account of one on Green Turtle Cay ‘seen by everyone’; and Kelley for her 2008 one in Galleon Bay canal… of which she actually got a photo…

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To give you an idea of the rapid spread of the West-Indian Manatee population, here is a great infographic made recently by Felice Leanne Knowles of the BMMRO, mapping 2016 sightings of both known and unidentified manatees in the Bahamas. An amazing 15 in all, in an area where the natural fresh water these creatures need for survival is in short supply.

Bahamas Manatee sightings infographic (BMMRO / Felice Knowles)

You’ll see that in July both Gina and Rita had nosed their way down to Andros. At this time, Gina was known to be heavily pregnant. She gave birth in Kamalame Cay, and the photos of her above with her new calf were taken there.

The baby manatee is known to be a female and there is currently a competition to name her. A spreadsheet-worth of names was submitted to the BMMRO, and they have been whittled down to 3 for a final poll-off between Andie (Andros), Kaman (Kam[alame] An[dros]) and Morgan (Arrrrrrrr in Piratese). 

Waiting for a name…Rita the Mantee & her new baby. Bahamas (BMMRO)

RELATED LINKS

BAHAMAS MANATEE CLUB (BMMRO)

BAHAMAS MANATEES: GINA’S GOOD NEWS

BAHAMAS MANATEES: A SHORT HISTORY 1904 – 2015

WEST INDIAN MANATEES (RH PAGE)

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Credits: BMMRO and individual photographers whom I will identify when my backup has finished churning away; Felice Leanne Knowles; ‘Kelly’ (header); @kamalamecay; Sarah Jayne Buchanan; Peppermint Narwhal for their (as usual) inspired illustrative graphics.

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PREHENSILE TALES FROM THE REEF (2): HIPPOCAMPI


Seahorse (© Adam Rees / Scuba Works)

PREHENSILE TALES FROM THE REEF (2): HIPPOCAMPI

It is a statistical fact that no one in the world – not even the meanest despot or cruellest tyrant – fails to love seahorses. It would be fair to add that in certain parts of the world, some people love them too much. In more than 65 countries. To the tune of an estimated 150 million a year that are used in the ‘traditional medicine’ trade. An attrition rate that is unsustainable in the long or even the medium term – with the bleak consequence that it won’t be long before people must look elsewhere for their source for Genital Tonic Pills. 

Seahorse (Adam Rees / Scuba Works)Seahorse (Adam Rees / Scuba Works)

Medicinal use – of empirically vague benefit to its enthusiasts – is joined by the aquarium trade in accounting for the removal of very large numbers of seahorses from their accustomed surroundings. At least these creatures live on (rather than being dried out alive), though research suggests that the survival rate of seahorses in captivity is low. 

Seahorse (Adam Rees / Scuba Works)

Do you sometimes hanker for a plastic brooch or paperweight with a tiny seahorse embalmed inside it? It would be good to resist the temptation to buy such things in seaside shops or online. Your little specimen will be one of a million or so souvenir seahorses sold each year, alongside seashells, starfish, sponges and (protected) corals. 

Seahorse (Adam Rees / Scuba Works)

As you contemplate your purchase, you may be reassured to find that the product is labelled ‘environmentally friendly’, ‘responsibly sourced’ or ‘from a sustainable source’. You can make up your own: ‘lovingly harvested from the bluest oceans’, maybe. In the words of the SEAHORSE TRUST: 

“Nothing could be further from the truth; there is nothing sustainable about this exploitation of the seas. You can make change by not buying them. If there was no market there would be no trade.”

Seahorse (Adam Rees / Scuba Works)Seahorse (Adam Rees / Scuba Works)

USES FOR SEAHORSES: MEDICINE OR (WITH SCORPIONS) STREET FOOD  images-1 seahorses_scorpions_skewer

seahorse-adam-rees-scuba-worksSeahorse (Adam Rees / Scuba Works)

RELATED POSTS AND ONLINE RESOURCES

HIP HIP HIPPOCAMPUS!

PREHENSILE TALES 1

SEAHORSE TRUST

SEAHORSE TRUST FB GROUP

SEAHORSES: NAT GEO

                   Sustainable Seahorses

s-l225-2      s-l225-1

Credits: Adam Rees / Scuba Works for more stunning photos; Seahorse Trust for material; Wiki & open source for the random thumbnails

SILVERSIDES: BAHAMAS REEF FISH (32)


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SILVERSIDES: BAHAMAS REEF FISH (32)

I have no idea if there is a collective noun for a large group of silversides. ‘Frenzy’ would cover it, but that is reminiscent of ‘feeding freezing’ which has a specialist meaning – and anyway, silversides are crazy even when they aren’t feeding. 24/7/12/365 as far as I can make out. I think ‘a panic of silversides’ might be the answer. They are just… all over the place at high speed. Sometimes swirling around pointlessly, other times moving in unison and suddenly all changing direction simultaneously, like a single creature made of tiny shards of silver.

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There are quite a few silverside species around the world. The ones in the Bahamas are Atlantic silversides (Menidia menidia), also known in the north east of the United States as ‘spearing’. They seem to exist for two purposes. The main one is to be breakfast, lunch or dinner for larger fish, sea birds and shore birds. The other is for their usefulness in scientific research because of their sensitivity to environmental changes. 

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In one sense they are easy prey for predators. A determined fish will always manage a snack by swimming into the middle of a panic and (probably) simply by opening its mouth wide. On the other hand, their sheer numbers coupled with the speed and randomness of movement mean that a single may find a degree of safety in numbers. It’s hard for a predator to target any individual fish in the general melee and confusion. Silversides also favour seagrass beds, which give some shelter and protection – and a reasonably safe place to spawn. Or, as some of these photos show, they will hang around wrecks or squeeze into rocky spaces in the reef.

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A panic of silversides apparently pouring like a waterfall down through a gap in the reefsilversides-waterfall-abaco-kay-politano

WHAT DOES A STATIONARY ATLANTIC SILVERSIDE LOOK LIKE?

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Some time ago we used to go to the reef at Fowl Cay Marine Preserve with Kay Politano, and I would snorkel with a small and very basic lo-res underwater camera. I was hampered by being a disgracefully feeble swimmer; by not having snorkelled for a length of time calculable in decades; and by being a complete novice at underwater photography.  Despite these not inconsiderable disadvantages I managed to cobble together a few short movies on my computer (I was new to that too). Here’s one that nearly works, in that it gives an idea of what happens if you ‘swim with silversides’. I know you scuba guys all swim with sharks, but cut me some slack here please…

Photo Credits: Main photos Melinda Riger of Grand Bahama Scuba; Silverside Waterfall by Kay Politano; motionless silversides by FISHBASE.ORGMusic: Goldon Giltrap, ‘Fast Approaching’