COOKIECUTTER SHARKS: BEASTLY LITTLE SUCKERS


Cookiecutter Shark mouth, jaws & teeth (BMMRO Bahamas)

COOKIECUTTER SHARKS

BEASTLY LITTLE SUCKERS

The Cookiecutter shark Isistius brasiliensis (aka the less scary, more genial sounding ‘cigar shark’), might be an ideal candidate for a Room 101 nemesis.** These little beasts – a species of dogfish shark – are found in several mainly island-based areas dotted around the globe, including in Bahamas waters.

 

HOW COME THE NAME?
These sharky little b@st@rds (*scientific term*) attack marine mammals and fishes, attaching themselves by suction and gouging out perfect round plugs of skin and flesh, leaving what are sometimes called ‘crater wounds’. Then they eat them. Imagine getting hold of a really sharp domestic cookie cutter with circular rows of razor-sharp teeth, and grinding it hard into your thigh. There! That! 
The size of an adult shark:16″ max
The term ‘cookiecutter’ is also a pejorative slang term, meaning mass-produced, lacking in originality, or boringly samey, as in cookiecutter cars or TV genres etc. The little critters under consideration here are anything but…
                        

HORRIFYING COOKIECUTTER FACTS

  • Live in the depths, rise vertically in the day & dive back down at dusk
  • Undersides have light-emitting ‘photophores’ which emphasise…
  • …the dark collar which acts as a lure, resembling a small innocent fish
  • Bioluminescence lures prey & confuses predators (more on this below)
  • The glow is so strong it may last for some time after removal from water

  • Their lips are ‘suctorial’ = they attach tightly to their target
  • The jaws then gouge out the victim’s flesh in a remarkably neat circle
  • Omni-vicious: any medium to large ocean creature is vulnerable to attack
  • There are even occasional reports of humans being targeted

Here are two Blainville’s beaked whales that I photographed from the BMMRO research vessel. The top whale has a number of circular healed attack marks and a recent one. You can see how deep the gouged hole is. The other has well-healed scars.

Blainville's Beaked Whale - cookiecutter shark damage (Keith Salvesen)Blainville's Beaked Whale - cookiecutter shark damage (Keith Salvesen)

  • Multi-toothed: top rows of small teeth, rows of larger teeth on the bottom
  • The lower teeth are the cutters, acting like a saw when locked on
  • See header image and below for full details

    

HOW EXACTLY DO THEY DO WHAT THEY DO?
I can explain it no better than the renowned authority Prof. W. K. P. Dear:  “the suctorial lips ensure a tight seal. It then bites, using its narrow upper teeth as anchors while its razor sharp lower teeth slices into the prey. Finally, the shark twists and rotates its body to complete a circular cut, quite possibly aided by the initial forward momentum and subsequent struggles of its prey. The action of the lower teeth may also be assisted by back-and-forth vibrations of the jaw, a mechanism akin to that of an electric carving knife”.

                 ARE THESE SHARKS ‘PARASITES’, WOULD YOU SAY?

The behaviour of these sharks is an example of a symbiotic relationship between two species that is parasitic. This means essentially that one gains and the other suffers (eg humans & no-see-ums). This is distinct from commensalistic symbiosis, where one species gains and the other is unaffected (e.g. cattle egrets with cattle); and mutualistic symbiosis, where both gain (e.g. cleaner fish & groupers). So, in a word, yes.

  • An ‘ambush predator’: these little sharks ‘hover’ in the water column waiting…
  • They are capable of rapid movement to catch up & latch onto prey
  • They will eat a passing small fish, crustacean or even squid as a snack
  • Sometimes they operate in schools; there is safety in numbers
  • The schools are thought to increase the ‘lure’ effect of the dark collar

A beached whale that’s been heavily targeted

FUN FACT TO COUNTERACT THE BAD STUFF

In the late c20, more than 30 U.S. Navy submarines were forced back to base to repair damage caused by cookiecutter shark bites, either to the neoprene footings of sonar domes or to rubber-sheathed cables. The problems were solved by using fibreglass. Oceanographic equipment and telecommunications cables are also recorded as being damaged by these sharks.

Cookiecutter Shark – the real deal

MONSTERS OF THE DEEP

These great cards from the weirdly spelled WIERD ‘N’ WILD CREATURES provide excellent factual info. Their CCS card is no exception. You’ll find more details here about the effect of the bioluminescence and so on, written as clearly as I might hope to. 

Cookiecutter Shark Facts (Monsters of the Deep)Cookiecutter Shark Facts (Monsters of the Deep)

** “The worst thing in the world varies from individual to individual. It may be burial alive or death by fire, or by drowning, or by impalement, or fifty other deaths. There are cases where it is some quite trivial thing, not even fatal.” (George Orwell, 1984). Being in a tank with some cookiecutters might count.

Alright now… the wounds eventually healBlainville's Beaked Whale - cookiecutter shark damage (Keith Salvesen)

Credits: BMMRO – header image; beaked whale photos – Keith Salvesen / BMMRO; Te Ara NZ for the main jaw image; all small images with thanks to Wiki and respective photographers who took the time to upload them for all to enjoy & learn from; ‘wierdnwonderful creatures’ for the monster card; range map from Wiki

IS THIS THE REAL LIFE? IS THIS JUST FANS AT SEA?


Purple sea fan, Bahamas (Melinda Riger / Grand Bahama Scuba)

IS THIS THE REAL LIFE? IS THIS JUST FANS AT SEA?

I am re-posting this sea fan article as 2021 rolls over into 2022 with much the same disruption, anxiety, and (for many) grief that we were all facing a year ago. The converse and somewhat rhapsodic title reflects the experience of many people since Covid engulfed the world. Life has become simultaneously real and surreal. It continues in many respects as normal yet who would have guessed that as we entered a new decade in 2020, the face mask would quickly become an essential (or anyway a medically recommended) part of daily life and remain so? 

This post was written at a time of sunshine, normality and optimism, before Covid and even before the violent destructive force of Dorian in autumn 2019. Here’s some cheer from sea fans on the coral reefs of the Bahamas.  

GALLERY OF GORGONIANS 

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

The waters of Abaco teem with myriads of fish that depend on the coral reefs for shelter and safety, for breeding, for growing up in, and for nourishment. Sea fans (or gorgonians, to use the technical name) are animals too. They may look like plants and stay rooted to the spot, but like anemones these ‘soft corals’ are creatures of the reef and essential indicators of its health.

Purple sea fan, Bahamas (Melinda Riger / Grand Bahama Scuba)

Purple sea fan, Bahamas (Melinda Riger / Grand Bahama Scuba)

The purple sea fan Gorgonia ventalina (classified by Linnaeus in 1785) is one of the most common species of sea fan, and a spectacular one at that. The main branches are linked by a lattice of smaller branches. Below the ‘skin’ is a skeleton made of calcite compounded with a form of collagen.

Purple sea fan, Bahamas (Melinda Riger / Grand Bahama Scuba)

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

Sea fans are filter-feeders, and have polyps with eight tiny tentacles that catch plankton as it drifts past. They develop so that their orientation is across the prevailing current. This maximises the water passing by and consequently the supply of food as the fans gently wave in the flow.

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

Gorgonians have a chemical defence mechanism that protects against potential troublemakers. The main effect is to make themselves unpleasant to nibble or uproot.

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

One species impervious to this deterrent is the fascinating FLAMINGO TONGUE SNAIL. Other ‘safe’ species include the fireworm and BUTTERFLYFISHES.

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

One benefit of sea fans to mankind is that their defensive chemicals have been discovered to provide the basis for drug research and development, specifically in the field of  anti-inflammatories. Another benefit, of course, is that they are very beautiful to look at. And in bad times, that can only be good .

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

Credits: these wonderful photos were taken by Melinda & Keith Rodgers / Dive Abaco, Marsh Harbour; and Melinda & Fred Riger / Grand Bahama Scuba. Huge thanks to them all for allowing me to freely use their skilful underwater photography in this blog for the best part of a decade.

A SPECIAL FAN FOR A HAPPY AND HOPEFUL 2022

Purple Sea Fans, Abaco, Bahamas (Dive Abaco / Keith & Melinda Rogers)

BAHAMAS DOLPHINS: VIEW FROM A RESEARCH BOAT with BMMRO


Recent weather conditions have mostly been perfect for launching the new BMMRO boat and continuing with ongoing marine mammal research. The field work at the moment is one aspect of the ‘Saving Abaco’s Dolphins after Hurricane Dorian’ project.

Acoustic research involves deploying specialised recorders to monitor sub-surface noise levels such as ship-generated sound. This helps to determine the effects of underwater noise pollution on marine mammals. Areas of concern can be identified and monitored. Naturally the dolphins take a keen interest as well, and there is plenty of opportunity to enjoy their company out on the water.

More general research includes compiling intricate records of dolphins encountered, noting specific characteristics. The dorsal fin is generally the most helpful ID marker, as they are all different – especially when there is some wear and tear to go by.

BMMRO records for dolphins go back a long way, and often involve two or more generations of the same family. Amazingly, during the last few days, a dolphin was encountered whose mother was first seen as a calf in 1992…

BMMRO are hosting a meeting in Hope Town to explain recent work and its results

BMMRO intern Jaylen gets to admire dolphins at close quarters in the Sea of Abaco

Dolphin Research . Sea of Abaco . Bahamas . BMMRO – all photos © BMMRO

‘TERN, TERN, TERN’: THE UN-NOTORIOUS BYRD COUSINS


Royal Tern, Abaco Bahamas (Keith Salvesen)

‘TERN, TERN, TERN’: THE UN-NOTORIOUS BYRD COUSINS

There are twelve species of tern – ‘swallows of the sea’ – that to a greater or lesser extent may be found on Abaco. Whether they will actually  be visible at any given time is less certain, though. For a start, the only resident species is the lovely Royal Tern, available at many locations on Abaco and the cays throughout the year. The rest are migratory or just passing through.

PERMANENT RESIDENTS

ROYAL TERNS Thalasseus maximus PR1

Royal Tern, Abaco Bahamas (Keith Salvesen)Royal Tern, Abaco Bahamas (Keith Salvesen)

MIGRATORY TERNS: SUMMER

In the slightly less commonly-found category are the summer migrant terns that, by definition, are only in residence for around half the year. Four of these are fairly common in certain areas, and actually breed on Abaco; these include arguably the prettiest of all, the bridled tern. The other two tern species (gull-billed and sandwich) are more rare and as far as I can make out do not breed locally; or perhaps only rarely. 

LEAST TERN Sternula antillarum SR B 1

LeastTern, Abaco Bahamas (Tony Hepburn)

BRIDLED TERN Onychoprion anaethetus SR B 2

BridledTern, Abaco Bahamas (Bruce Hallett)BridledTern, Abaco Bahamas (Bruce Hallett)

ROSEATE TERN Sterna Dougallii SR B 2

Roseate Tern, Abaco Bahamas (Woody Bracey)

SOOTY TERN Onychoprion anaethetus SR B 2

Sooty Tern, Duncan Wright wiki

GULL-BILLED TERN Gelochelidon nilotica SR 3 

Gull-billed Tern, Abaco Bahamas (Alex Hughes)Gull-billed Tern, Abaco Bahamas (Alex Hughes)

SANDWICH TERN Thalasseus sandvicensis SR 4

Sandwich Tern, Abaco Bahamas (Bruce Hallett)Sandwich Tern, Abaco Bahamas (Woody Bracey)

MIGRATORY TERNS: WINTER

There is one very rare winter resident migratory tern species, with few records of sightings for Bahamas and until early 2019, no photographic record for Abaco until Sally Chisholm saw one at Treasure Cay and managed to capture it for posterity.

FORSTER’S TERN Sterna forsteri  WR 4

Forster's Tern (Dick Daniels)Forster's Tern, Abaco Bahamas (Sally Chisholm)

OCCASIONAL & RARE VISITORS

A further four tern species are very much occasionals that drop by. Three of them pass over the Bahamas on their longer migration, but may make a pit-stop around Abaco to take on fuel. Likelihood of sighting one? Slender but not impossible… the Caspian tern below was photographed on Abaco. The fourth, the Arctic Tern, is a very rare vagrant, a bird well away from its usual home or migration route as the result of storms or faulty satnav or sheer happenstance. Don’t travel to the Bahamas intent on seeing one.

CASPIAN TERN Hydroprogne caspia TR 4

Caspian Tern Abaco Bahamas (Woody Bracey)Caspian Tern Abaco Bahamas (Keith Kemp)

The remaining species are the transient black tern and common tern; and the vanishingly rare vagrant  Arctic tern. No photos of any of these I’m afraid. Here’s a handy checklist of all the tern species.

     ELECTIVE MUSICAL DIGRESSION

Written by Pete Seeger, Turn x 3 was released in 1965, the title track on the second album by The Byrds. At a rather febrile time in US history (Vietnam, draft riots, civil rightists v cops and so on), this unusually palliative and thoughtful song with its religious connotations to some extent stood for peace and hope in a time of turmoil.

PS the somewhat laboured title of this post shoehorns in the name of another Byrds album, ‘The Notorious Byrd Brothers’

Photo credits: Keith Salvesen (1, 2, 3, 5, 18); Tony Hepburn (4); Alex Hughes (10, 11); Bruce Hallett (6, 7, 12); Woody Bracey (8, 13, 16); Duncan Wright (9); Dick Daniels (14); Sally Chisholm (15); Keith Kemp (17)

Royal Tern, Abaco Bahamas (Keith Salvesen)

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)

ATLANTIC SPOTTED DOLPHINS . ABACO BAHAMAS


Atlantic Spotted Dolphins . Abaco Bahamas . BMMRO

ATLANTIC SPOTTED DOLPHINS – ABACO, BAHAMAS

There’s never ever a wrong time for dolphins to have some fun in the water. It’s what they expect. It’s what we (if we are lucky enough to see them) expect. It’s what they expect that we expect if we are out in a boat – hence the joyful bow-riding, the rapid crossing back and forth. From time to time there’s a single dolphin in a group that takes the opportunity to show off. In the deeper water off the southern tip of Abaco, in sight of the lighthouse, this is a good example of such carefree behaviour.

There’s more excitement to be found in this group. If you look carefully at #3 in the gallery, you’ll see a very small dorsal fin. There’s a calf in the group, being guided and watched over by two adults. Imagine being out there in a boat and encountering this group. That would in itself be something to show off about…

Atlantic Spotted Dolphins . Abaco Bahamas . @BMMRO
Atlantic Spotted Dolphins . Abaco Bahamas . BMMRO

All photos © Charlotte Dunn / Bahamas Marine Mammal Research Organisation (BMMRO). Please support the work of this specialist Bahamas marine mammal research team and help to preserve these increasingly vulnerable creatures LINK

SEAHORSES: PREHENSILE TALES FROM THE REEF


Seahorse (Adam Rees / Scuba Works)

SEAHORSES: PREHENSILE TALES FROM THE REEF

It’s a while since I showcased these astonishing little creatures. Adam Rees of SCUBA WORKS is a diver who combines great underwater experience with wonderful photographic skills. Here is a showcase for some of Adam’s seahorse photography and the amazing detail he captures. If these images don’t make you want to get your head underwater and explore the reefs, I can’t think what will…

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

RANGE MAP by NAT GEO

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

shlifecycle-e1313548153493

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

Seahorse by Alex Konahin

All fantastic photos: Adam Rees / Scuba Works; Range Map, Nat Geo; Lifecycle diagram, Seahorserun; Seahorse GIF, Alex Konahin

TUNICATES: SESSILE ASEXUAL SEA-SQUIRTS


Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

TUNICATES: SESSILE ASEXUAL SEA-SQUIRTS

Painted Tunicates Clavina picta are one of several species of tunicate ‘sea-squirts’ found in Bahamas and Caribbean waters. These creatures with their translucent bodies are usually found clustered together, sometimes in very large groups. One reason for this is that they are ‘sessile’, unable to move from where they have taken root on the coral.

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

HOW DO THEY FEED?

Like most if not all sea squirts, tunicates are filter feeders. Their structure is simple, and enables them to draw water into their body cavity. In fact they have 2 openings, an ‘oral siphon’ to suck in water; and an exit called the ‘atrial siphon’. Tiny particles of food (e.g. plankton) are separated internally from the water by means of a tiny organ (‘branchial basket’) like a sieve. The water is then expelled. 

Diagram of adult solitary tunicate

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

WHAT DOES ‘TUNICATE’ MEAN?

The creatures have a flexible protective covering referred to as a ‘tunic’. ‘Coveringcates’ didn’t really work as a name, so the tunic aspect became the name. 

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

IF THEY CAN’T MOVE, HOW DO THEY… (erm…) REPRODUCE?

Tunicates are broadly speaking asexual. Once a colony has become attached to corals or sponges, they are able to ‘bud’, ie to produce clones to join the colony. These are like tiny tadpoles and their first task is to settle and attach themselves to something suitable – for life – using a sticky secretion. Apparently they do this head first, then in effect turn themselves upside down as they develop the internal bits and pieces they need for adult life. The colony grows because (*speculation alert*) the most obvious place for the ‘tadpoles’ to take root is presumably in the immediate area they were formed.

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

APART FROM BEING STATIONARY & ASEXUAL, ANY OTHER ATTRIBUTES?

Some types of tunicate contain particular chemicals that are related to those used to combat some forms of cancer and a number of viruses. So they have a potential use in medical treatments, in particular in helping to repair tissue damage.

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

Credits: all fabulous close-up shots by Melinda Riger / Grand Bahama Scuba; diagram from depts.washington.edu; magpie pickings with a particular mention of an article by Sara MacSorley

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

TOPICAL FISHES: WHOLLY ANGELS


The images below show the three species of angelfish commonly found among the coral reefs of the Bahamas. These were photographed by diver Melinda Riger in the waters round Grand Bahama. The Queen, French and Gray Angels are shown in both adult and juvenile forms.

Queen Angelfish
Queen Angelfish (juv.)
French Angelfish
French Angelfish (juv.)
Gray Angelfish
Gray Angelfish (juv. to adult phase)

All photos: Melinda Riger / Grand Bahama Scuba

CHRISTMAS TREE WORMS: SEASONAL SPIROBRANCHES


Christmas Tree Worm (Melinda Riger / Grand Bahama Scuba)

CHRISTMAS TREE WORMS: SEASONAL SPIROBRANCHES

music-notes-clip-art-png-musicDeck 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 the perfect time to take a look at these remarkable subsurface symbols of seasonal good cheer (nb they are wonderful animals not gorgeous plants).

christmas-tree-worm-melinda-riger-g-b-scuba

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

Christmas Tree Worm (Neil Hobgood Wiki)Christmas Tree Worm (Melinda Riger / Grand Bahama Scuba)

  • 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… (see below for some action)

spirobranchus_giganteus_orange_christmas_tree_worm-nick-hobgood-wiki

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

This is a delicate area. They are very discreet, but as far as I can make out they eject gametes from their what-I-said-above. There are mummy and daddy worms, and their respective gametes (eggs and spermatozoa) drift in the current and into each other to complete the union. The fertilised eggs develop into larvae, which settle onto coral and burrow into it as their parents did, build their protective tubes, and the process begins again.

christmas_tree_worm-nick-hobgood-wiki

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).

The worms, in their coral burrows, hoist their pairs of ‘trees’. You can easily see small particles – zooplankton – drifting in the water, and the radioles swaying to catch potential food. Suddenly it all makes sense (except the repro bit – I haven’t found footage of that).  Next: the New Year Worm (there is no Easter worm).

A WHOLE FESTIVAL OF CHRISTMAS TREE WORMSChristmas Tree Worms (Neil Hobgood Wiki)

Credits: Melinda Riger (Grand Bahama Scuba); Nick Hobgood; Betty Wills; Video by ‘Super Sea Monkey’; Reef Collage by RH; MarineBio; Wikibits & Magpie Pickings

Happy Christmas to all those who put up with RH with such fortitude over the years
blue_christmas_tree_worm-betty-wills-wiki

WHALE TALES FROM BMMRO, ABACO BAHAMAS


Sperm Whale Tailing, Abaco Bahamas (Charlotte Dunn / BMMRO)

WHALE TALES FROM BMMRO, ABACO BAHAMAS

These photos of tailing sperm whales Physeter macrocephalus were taken in the last month or so off the coast of South Abaco, close to the HQ  of BMMRO (Bahamas Marine Mammal Research Organisation) at Sandy Point.

Sperm Whale Tailing, Abaco Bahamas (Charlotte Dunn / BMMRO)

The powerful tails, or flukes, of the sperm whale are the largest of any whale species relative to body size. As the whales prepare for a deep dive, the flukes are the last thing you’ll see…

Sperm Whale Tailing, Abaco Bahamas (Charlotte Dunn / BMMRO)

Marine mammals can be identified by individual characteristics such as tears to the fluke (whales – see header image), dorsal fin (dolphins) or ‘paddle’ (manatees). Many will be sighted and recorded, and later seen regularly, often for many years. Family dynasties can even be traced down the generations.

Sperm Whale Tailing, Abaco Bahamas (Charlotte Dunn / BMMRO)

The whale above is in the final stages of a dive, just before the fluke slides beneath the surface and vanishes. The dramatic moments that precede this, with the unforgettable sight of water pouring off the spread tail – are over. The hunt for deep-down squid has begun in earnest.

BMMRO research boat, Sandy Point Abaco Bahamas (Keith Salvesen / Rolling Harbour))

BMMRO Research RIB (with Harry)

Main Photos: Charlotte Dunn/ BMMRO

Sperm Whale Tailing, Abaco Bahamas (Charlotte Dunn / BMMRO)

INTERNATIONAL MANATEE DAY: BAHAMAS? WE GOTTEM!


West Indian Manatee, Bahamas (BMMRO / Charlotte Dunn / Keith Salvesen)

INTERNATIONAL MANATEE DAY: BAHAMAS? WE GOTTEM!

Manatees are apex ‘gorgeous marine mammals’. Gentle, inquisitive, brave, long-distance-but-rather-slow-swimming, grass-grazing miracle ur-elephant descendants. They never made it out of the sea in the Miocene epoch.

West Indian Manatee, Bahamas (BMMRO / Charlotte Dunn / Keith Salvesen)

Incongruous in a world of fast sharks, huge whales and leaping dolphins, they contentedly mooch around the seagrass beds. No one in the world has ever objected to or dissed a manatee. They bring only delight to the sea-world, and offer only charm to mankind.

West Indian Manatee, Bahamas (BMMRO / Charlotte Dunn / Keith Salvesen)

I’ve written quite often about the small number of manatees that inhabit the turquoise inner waters of the Bahamas. Almost all are named and some are tracked (until they lose their trackers). Their friendships and amorous hook-ups are recorded. Despite their relative scarcity in the Bahamas and a 16-month birth cycle, they produce manatee-lets and the family trees are very gradually growing.

West Indian Manatee, Bahamas (BMMRO / Charlotte Dunn / Keith Salvesen)

Gina and Calf, Bahamas (BMMRO)

IS THERE A DOWNSIDE FOR THESE APPARENTLY BLISSFUL AND PEACEFUL CREATURES?

Yes indeed. It’s mankind. Among the threats to the survival of these unusual, endearing, and legally protected creatures are, in no particular order:

  • Pollution of inshore waters and canals
  • Degradation of the (formerly limitless) sea-grass beds where they feed
  • Reduction or tainting of the fresh water sources that they need to survive
  • Understandable over-enthusiasm by admirers – especially in harbours – in dousing them with water from hoses and feeding them lettuce…
  • …and similar behaviours that may lead to a trusting dependance on humans
  • Unthinking or speed-selfish boat behaviour in or near harbours resulting in collisions
  • Simply not caring at all and carving them up, leaving often deep prop-scars. Few manatees escape at least a few of these. Some may not survive.

West Indian Manatee, Bahamas (BMMRO / Charlotte Dunn / Keith Salvesen)

Let’s celebrate this special day for manatees. Let’s hope that they can survive and prosper in these increasingly difficult and dangerous times for almost all species. Look at any of these photos… can we agree that these wonderful animals deserve care and protection.

All photos: Charlotte Dunn / BMMRO and research contributors

West Indian Manatee, Bahamas (BMMRO / Charlotte Dunn / Keith Salvesen)

SHARK ATTACKS – ABACO, BAHAMAS, & BEYOND


Shark! Melinda Riger, Grand Bahama Scuba

SHARK ATTACKS – ABACO, BAHAMAS & BEYOND

Over the last couple of weeks or so I have been getting a lot of hits for Shark Attack information. There have been 2 or 3 recent incidents including a tragic (and very rare) death in Maine, which may well account for this. The Shark Attack details I have accumulated and posted over the years are buried in an historical sub-sub-page, so to make things easier I have rechecked and updated the latest data resources and their links, and put them in a mainstream post. This is it.

DATABASE UPDATE 2020

INTERNATIONAL SHARK ATTACK FILE

PRIMARY RESOURCE

This resource is the portal to a mass of current, recent, and historical data, presented with authority and clarity. It provides undoubtedly the most comprehensive and accessible global shark-incident data of all.

Last year I included informative screen-shots taken from this site. For now I am confining the information to the most useful direct links. More work for the reader, perhaps, but also a better chance to explore and understand the hows, whens and wherefores of shark-related incidents – and how best to avoid the situation in the first place.

SITE LINK

https://www.floridamuseum.ufl.edu/shark-attacks/

BAHAMAS-SPECIFIC

https://www.floridamuseum.ufl.edu/shark-attacks/maps/na/bahamas-antilles/

The 2019 worldwide total of 64 confirmed unprovoked cases were lower than the most recent five-year (2014-2018) average of 82 incidents annually. There were five fatal attacks this year, two of which were confirmed to be unprovoked. This number is in line with the annual global average of four fatalities per year

MENU SELECTION

 Maps & Data    Contributing Factors    Shark Attack Trends 

What are the Odds?   Reducing Your Risk

For anyone thinking of entering waters where sharks live – eg scuba divers, spear-fishers, swimmers, boaters – with relatively little experience or knowledge, these links will be incredibly useful. Local knowledge is well worth having as well. A young friend of ours, an intern on Abaco, was warned against spearfishing at a particular location: “Fish there, you’ll get ate”. He did. He very nearly was.

“Humans are not on the menu of sharks. Sharks bite humans out of curiosity or to defend themselves”

The SRI produces a  downloadable Global Shark Attack File that provides:

  • A downloadable incident log by country
  • A downloadable incident log chronologically
  • A world map of encounters categorized by provoked vs. unprovoked, incidents involving boats, air & sea disasters and questionable incidents
  • To read any basic case report, open the Chronological file, click on the case number (column A) and the report will open as a pdf file

SHARK SPECIES (CONCISE OVERVIEW FOR EACH SHARK)

http://www.sharkattackfile.net/species.htm

BAHAMAS-SPECIFIC STATS

http://www.sharkattackdata.com/gsaf/place/bahamas

ABACO-SPECIFIC STATS

http://www.sharkattackdata.com/gsaf/place/bahamas/abaco_islands

Credits: All great shark photos – Melinda Riger / Grand Bahama Scuba; ‘Infest’ sticker design, Tracie Sugo

A FINAL THOUGHT

 

WORLD OCEANS DAY: WHAT YOUR DESCENDANTS MAY MISS


Bottlenose Dolphins Abaco, Bahamas (Charlotte Dunn / BMMRO)

WORLD OCEANS DAY: WHAT YOUR DESCENDANTS MAY MISS

Even the most optimistic lovers of unmolested wildlife, unpolluted oceans, un-degraded habitats, unextinguished species and understanding humans will be beginning to lose heart. Even as reports increase of resurgent wildlife during these Covid months, so it is gradually becoming clear that once humans are unlocked again, the only way will be down. 

Humpback whaleHumpback Whale, Abaco, Bahamas (Charlotte Dunn / BMMRO)

Here are just a few magnificent marine mammals to admire. All were photographed from the BMMRO research vessel in Abaco or adjacent waters. They are protected, recorded, researched, and watched over in their natural element – some individuals for more than a decade. 

Pantropical spotted dolphinsPan-tropical spotted dolphins, Abaco, Bahamas (Charlotte Dunn / BMMRO)

Today we contemplate our oceans at a time when the human species is having to confront a sudden and indiscriminate destructive force. Maybe the impact will lead to a recalibration of the ways we treat other species and their environment. We have contaminated the world’s oceans, perhaps irreparably, in a single generation. We could start by committing our support to those that tackle the plastic saturation, oil / chemical pollution, acoustic bombardment, ‘ghost gear’, and all the other unwelcome attritional activities we are responsible for. We could continue by supporting those that monitor and protect all the marine creatures struggling in a polluted environment that, in natural law, should be theirs.

Bottlenose DolphinsBottlenose Dolphins, Abaco, Bahamas (Charlotte Dunn / BMMRO)

Below is a male Blainville’s beaked whale, with its remarkable barnacled tusks that protrude upwards from its lower jaw. This is a specialist research species in the Bahamas. Below that is a short video of these whales that I took from the BMMRO research vessel. Turn up the volume – you will clearly hear them breathing as they slowly pass by (and others in the group, under) the boat. Note that land is clearly visible. These whales can sometimes be found just beyond the shallow turquoise waters, where the sea deepens as the depth drops down to an underwater canyon.

Blainville’s beaked whale (m)Blainville's Beaked Whale Abaco, Bahamas (Keith Salvesen / BMMRO)

Hope for the future…Sperm whale - neonate calf Abaco, Bahamas (Charlotte Dunn / BMMRO)

All photos taken in (or adjacent to) Abaco waters, Bahamas: Charlotte Dunn / Bahamas Marine Mammal Research Organisation (BMMRO), except for the beaked whale image and video by Keith Salvesen / Rolling Harbour (BMMRO)

Note: prognostications and personal views – and their intensity – detectable here are mine and do not necessarily reflect those of my colleagues at BMMRO… 

Farewell – but not goodbye, we must hope…Sperm Whale, Abaco, Bahamas (Charlotte Dunn / BMMRO)

ENDANGERED SPECIES, ABACO (3): NASSAU GROUPER


Nassau Grouper (Melinda Riger / G B Scuba)

ENDANGERED SPECIES, ABACO (3): NASSAU GROUPER

The Nassau grouper Epinephelus striatus is one of a number of grouper species found in Bahamian waters. Of these, only the Nassau grouper is on the IUCN Red List, as Critically Endangered. When I last wrote about them they were in the lesser category ‘Threatened’.

Nassau Grouper (Melinda Riger / G B Scuba

In order to sustain a viable population, it is vital to maintain numbers and preferably to increase them year on year. Once it became clear that year-round commercial overfishing was a prime component of the steep decline in the population, a 3-month closed season during the breeding period was imposed. This has ensured that at the most critical time in the lifecycle of the species, the groupers are left alone to breed in peace and to perpetuate their species.

Nassau Grouper (Melinda Riger / G B Scuba)

The closed season operates from December to February to maximise the chances of breeding success. As with some other fish species, reproduction occurs around the full moon. The fish gather at spawning sites and the process is at its height around sunset.

Nassau Grouper (Melinda Rogers / Dive Abaco)

10 CONVENIENTLY COLLECTED NASSAU GROUPER FACTS

  • An adult can grow to more than a metre long, and weigh 25 kg
  • They tend to be solitary daytime feeders, eating small fish & crustaceans
  • Their large mouths are use to ‘inhale’ or suck in prey
  • The colouring of an individual can vary from red to brown
  • These fish have little black spots around the eyes (I’ve no idea why).
  • Their habitat is in the vicinity of coral reefs, from shallows to 100 m deep
  • Spawning mainly occurs in Dec & Jan during a full moon
  • Large numbers gather in a single location to mate in a mass spawning
  • These groupers are slow breeders, which compounds the overfishing problem
  • They are easy mass targets at spawning time; hence the need for a closed season

Nassau Grouper (Melinda Riger / G B Scuba)

A Nassau Grouper glumly contemplates the possibility of extinctionNassau Grouper (Melinda Riger / G B Scuba)

RELATED POSTS

BLACK GROUPER

TIGER GROUPER

RED HIND

CLEANING STATIONS

Nassau Grouper (Melinda Rogers / Dive Abaco)

Credits: Melinda Riger / Grand Bahamas Scuba (1, 2, 3, 5, 6); Melinda Rogers / Dive Abaco (4, 7)

SEA URCHINS: PICTURE PERFECT ABACO (11)


SEA URCHINS: PICTURE PERFECT ABACO (11)

Sea Urchin, Abaco, Bahamas (Melinda Rogers / Dive Abaco)

As every swimmer knows, or eventually finds out the hard way, it’s not only Blue Suede Shoes that should not be stepped on. But however painful the consequences of a misstep, it’s hard not to find some beauty in an urchin living in a thriving reef environment. The wonderful anatomical diagram by Alex Ries shows everything you could conceivably want to know about one of nature’s most proficient foot-stabbers (if only all such diagrams were presented so simply and clearly).

Sea urchin anatomy (Alex Ries)

The internal organs depicted resemble a bad trip in the bowels of a vacuum cleaner; or (narrow your eyes) an experimental painting from one of the less successful schools of early c20 modern art, soon to be swept aside by Cubism. Note that the mouth is located where you might expect to find the opposite end, and vice versa.

I photographed the urchin test (skeleton) below at Delphi. It was large and almost entirely undamaged (very rare in my experience). The bright faintly greenish white is set off by the palest of pinks. Whatever your view of how creatures came to exist, imagine the creation or evolution of calcium carbonate into a small symmetrical structure as beautiful, detailed and complex as this. If you are short of a lockdown recreation, maybe try to draw it.

Sea Urchin Test / Skeleton, Abaco Bahamas (Keith Salvesen / Rolling Harbour Abaco)

Photo credits: #1 Melinda Rogers / Dive Abaco; #2 Anatomy Diagram, Alex Reis (5 stars for making it available free on Wikimedia); #3 Keith Salvesen / Rolling Harbour Abaco

CORAL SUNSHINE: PICTURE PERFECT ABACO (9)


CORAL SUNSHINE: PICTURE PERFECT ABACO (9)

coral-in-sunlight-melinda-rogers-dive-abaco

Off the east coast of Abaco lies one of the longest barrier reefs in the world. Some authorities suggest it is the third longest, but the exact ranking of the top dozen coral barriers is a matter for considerable debate. None of the lists I have just checked agree, except that the Great Barrier Reef is the outright winner. I suspect that the problem lies in the loosely generalised description of ‘barrier reef’ and in variations of the appropriate criteria for determining length (it may also depend on who is doing the measuring, of course).

Melinda Rogers of Dive Abaco took this bright sunlit ‘Coralscape’ in the Fowl Cays National Park. It’s a place I have tentatively snorkelled around with great pleasure, despite being in the top dozen most useless swimmers in the world (my appalling underwater videos were disqualified from the rankings for being… rank).

SPERM WHALE BONES & RESEARCH: LIFE AFTER DEATH


SPERM WHALE BONES & RESEARCH: LIFE AFTER DEATH

I made this short video last year at BMMRO HQ, Sandy Point, Abaco. A sperm whale had stranded earlier in the year, and after the necropsy some of the bones were taken from the beach for research. In order to clean them, the bones were sunk and anchored to the seabed offshore in quite shallow water. Strandings are always sad, of course, but  it is good to know that even after death the creature makes an important contribution to scientific research. In a sense, it has life after death.

BMMRO / Rolling Harbour Abaco / Keith Salvesen

GROUPER AT THE CLEANERS: PICTURE PERFECT BAHAMAS (5)


GROUPER AT A CLEANING STATION: PICTURE PERFECT BAHAMAS (5)

BLACK GROUPER AT A CLEANING STATION (Melinda Riger @ G B Scuba)

This black grouper (‘Arnold’) is at a so-called CLEANING STATION, being groomed by gobies. The process is an example of species symbiosis known as MUTUALISM. This is a transaction between individuals of two species that is mutually beneficial. Here, the primary creature pauses at a locally familiar cleaning station and allows itself to be expertly cleaned by tiny fishes such as gobies and wrasses to remove parasites, dead skin and so forth. This nurture even includes, as here, inside the mouth and gills. The gobies benefit by feeding on the proceeds of their endeavours removed from the host (or ‘client’ as one might say). And of course, in return for their favours a collateral benefit is that they can feed freely without being eaten by a potential predator. 

Credit: Melinda Riger / Grand Bahama Scuba

MANATEES: PICTURE PERFECT ON ABACO (4)


MANATEES: PICTURE PERECT ON ABACO (4)

MANATEE APPRECIATION DAY 2020West Indian Manatee, Abaco, Bahamas (Charlotte Dunn / BMMRO)

Mrs RH and I are sticking to self-isolation right now (we are fine, but thank you for asking). However I am already breaking my current self-imposed ‘single-picture-and-not-much-writing’ regime with today’s creature feature. The excuse? It is of course the last Wednesday in March and as everyone must know it is Manatee Appreciation Day.

Anyone can (and indeed should) appreciate manatees anywhere at any time, and their contemplation is a way to lift the spirits. They were first found in Abaco waters about a dozen years ago. BMMRO reported their movements and the ongoing research. Later, Bahamian locals enthusiastically followed the lives of Gina, Rita, Georgie, Randy & co; and the calves such as JJ and Sayle (winning name in a public competition). Citizen scientist reports were invaluable to the research. Unsurprisingly, since Hurricane Dorian reports have greatly reduced. Manatees may well still be around but even now, 6 months later, trichechi sightings are sporadic. There are other concerns, after all.

West Indian Manatee, Abaco, Bahamas (Charlotte Dunn / BMMRO)

Manatees love the camera and, Madonna-like, are often pleased to ‘strike the pose’. Of a sort.

West Indian Manatee, Abaco, Bahamas (Charlotte Dunn / BMMRO)

West Indian Manatee, Abaco, Bahamas (Charlotte Dunn / BMMRO)

Today the Marine Conservation Society (MCS) showed their appreciation for manatees with a superb image and an excellent set of Manatee Facts that I recommend to anyone who has read this far. For example, recent broadcasts and news articles have featured the importance of seagrass. You will see that it is the primary diet of manatees. 

View this post on Instagram

Happy #ManateeAppreciationDay! ☺️ We have a great photo-feature of these amazing animals in the Spring issue of our magazine coming to all members in the next few days but whilst you wait, here are some fun facts about them: ⠀ ⠀ 💙The manatee, also known as a 'sea cow', is a large marine mammal with an egg-shaped head, flippers and a flat tail. ⠀ 💙Manatees range in size from 8 to 13 feet (2.4 to 4 meters) and can weigh 440 to 1,300 lbs. (200 to 590 kilograms). ⠀ 💙Although they may seem like cumbersome creatures, manatees can swim quickly and gracefully.They have strong tails that power their swimming and usually swim about 5 mph but they can swim up to 15 mph (24 km/h) in short bursts ⠀ 💙There are three species of manatee: the Amazonian manatee, the West Indian/American manatee and the African manatee. ⠀ 💙Manatees often swim alone or in pairs. If manatees are seen in a group (called an aggregation), it is either a mating herd or an informal meeting of the species simply sharing a warm area that has a large food supply. ⠀ 💙Manatees are herbivores. At sea, they tend to prefer sea grasses. When they live in rivers, they consume freshwater vegetation. Manatees also eat algae. It's reported that a manatee can eat a tenth of its own weight in 24 hours! ⠀ 💙The IUCN's Red List of Threatened Species lists all manatees as vulnerable or endangered and facing a high risk of extinction. ⠀ Manatees are thought to have evolved from four-legged land mammals more than 60 million years ago. Except for the Amazonian manatee, their paddlelike flippers have vestigial toenails — a remnant of the claws they had when they lived on land. ⠀ 💙Manatees' eyes are small, but their eyesight is good. They have a special membrane that can be drawn across the eyeball for protection. ⠀ 💙Manatees don't always need to breathe. As they swim, they poke their nose up above the water's surface to catch a few breaths every few minutes. If they are simply resting, they can stay under the water for 15 minutes without taking a breath ⠀ ⠀ #marinemammal #marineconservation #marnebiology #marinelife #oceanlife #oceanindoors #manatee ⠀ ⠀

A post shared by Marine Conservation Society (@mcs_uk) on

Credits: Photos #1 – #4 Charlotte Dunn / Bahamas Marine Mammal Research Organisation (BMMRO) and #5 Caine Delacy / BMMRO; MCS UK

MCS links: https://www.mcsuk.org; https://www.facebook.com/mcsuk/

Gina with her calf SayleWest Indian Manatee, Abaco, Bahamas (Caine Delacy / BMMRO)