‘SOCIABLE DOLPHINS’: MELON-HEADED WHALES


Melon-headed whales, Bahamas (BMMRO / Field School)

‘SOCIABLE DOLPHINS’: MELON-HEADED WHALES

Last month, BMMRO undertook a joint expedition with FIELD SCHOOL to carry out research on sperm whales. This took them out into deep water, where another, quite different, cetacean species was also encountered on the final day – a huge pod of more than 100 melon-headed whales Peponocephala electra.

Melon-headed whales, Bahamas (BMMRO / Field School)

The melon-headed whale is in fact – like the FALSE KILLER WHALE I recently wrote about – a species of dolphin. It is sometimes more accurately called the melon-headed dolphin, which removes any confusion. These creatures are oceanic, preferring deeper waters. For that reason they are not often encountered, despite being quite common in tropical and sub-tropical waters around the world.

Cetacea range map Melon-headed Whale.PNG

Melon-headed whales, Bahamas (BMMRO / Field School)

The MHW belongs to a dolphin species commonly known as blackfish. Other dolphins in this group included, for the Bahamas, the pygmy killer whale and the more frequently encountered pilot whale, a species than can be seen in the Sea of Abaco.

In some of these photos you can see the distinctive white lips of the MHW Melon-headed whales, Bahamas (BMMRO / Field School)

Melon-headed whales are notably social animals. They live in large groups – often more than 100-strong (as the expedition found), up to as many as 1000 individuals. Within these large groups, smaller groups of a dozen or so form and stay close as they swim.

Note the ‘Rainbow Blow’ caught in this photoMelon-headed whales, Bahamas (BMMRO / Field School)

MHWs appear to communicate or perhaps to bond by touching flippers. MHWs also associate with other dolphin species, and they have even been recorded with large whales such as humpbacks.

Melon-headed whales, Bahamas (BMMRO / Field School)

Other observed behaviour includes sub-surface resting in numbers, boat-wave riding, and so-called ‘spy hopping’ (above). This last activity may be carried out by several resting animals,  which jump vertically out of the water and splash back again into the ocean (see also the Header image).

Melon-headed whales, Bahamas (BMMRO / Field School)

This video was recorded during the expedition. You’ll get a very good idea of the size of the group from the drone shots as they pull out. I doubt that many people would expect to see such large sea creatures in such numbers – it must be an awesome** sight.

10 MELON-HEADED FACTS WITH WHICH TO ASTOUND YOUR LOVED ONES
  • The MHW’s head is rounded, lacking the obvious beak of more familiar dolphins
  • The darker grey face is sometimes called a ‘mask’
  • Their distinctive white lips are a good identifying feature
  • They are capable of swimming at very fast speeds
  • Like other dolphins, they make series of low jumps out of the water as they swim
  • Their groups often contain 100 individuals, up to as many as 1000
  • An adult grows to around 3m / 10′ long
  • They live for at least 20 years, and females may live as long as 30 years
  • As with many certaceans, their favourite food is squid
  • Oh, did I mention that they are really dolphins and not whales at all?

CREDITS: all fantastic photos & the original of the video clip – © BMMRO /  Field School

** In its true and original meaning of ‘inspiring wonder and awe’ (historically, in a religious sense), rather than the diluted modern usage as in ‘awesome pizza’ or ‘awesome selfie’

FLORAL CORAL: REEF GARDENS IN THE BAHAMAS


Reef Corals, Bahamas (Melinda Riger / G B Scuba)

FLORAL CORAL: REEF GARDENS IN THE BAHAMAS

Like many of the blues musicians who covered Robert Johnson’s originals, we got ramblin’ on our minds. Specifically to ‘Delphi East’ in Ireland, thus stupidly exchanging 82F sunshine in southern UK for 46F rain in the Emerald Isle. Good for the fishing, if nothing else… So (always remembering that corals are actually creatures and not plants) here’s a bouquet of coral to be going on with until we next meet with wifi!

Reef Corals, Bahamas (Melinda Riger / G B Scuba)Reef Corals, Bahamas (Melinda Riger / G B Scuba)Reef Corals, Bahamas (Melinda Riger / G B Scuba)Reef Corals, Bahamas (Melinda Riger / G B Scuba)Reef Corals, Bahamas (Melinda Riger / G B Scuba)Reef Corals, Bahamas (Melinda Riger / G B Scuba)

OPTIONAL MUSICAL RAMBLING

Robert Johnson’s output – a meagre 29 songs in all – formed the bedrock for later bluesmen and the blues / rock crossovers that followed. They mined Johnson’s talent and formed their own new material from it. Here’s the original – you’ve probably heard it or variations of it with different names, a thousand times – some good, some bad, most so-so. 

Entire coral pot pourri by Melinda Riger / Grand Bahama Scuba

‘CURIOUS GEORGE’ THE INQUISITIVE BLACK GROUPER


Black Grouper Bahamas (Curious George) - Melinda Riger / GB Scuba

‘CURIOUS GEORGE’ THE INQUISITIVE BLACK GROUPER

Fish, like humans, have a wide variety of temperaments, or so it seems. Resorting to anthropomorphic analysis of animal behaviour is a favourite pastime for humans. Who really knows if a creature is actually feeling shy or confident or playful or aggressive or indeed inquisitive. Often it just seems that way and we are happy to categorise dolphins as playful, sharks as vicious, angelfish as serene, small darting fish as timid and so on. 

Black Grouper Bahamas (Curious George) - Melinda Riger / GB Scuba

Occasionally a creature displays a ‘human’ characteristic that seems undeniable. One such is Curious George. He has become used to the divers around the reef where he lives, and greets them. He enjoys the photography sessions and the equipment, even though they may be for recording other fish. He demonstrates inquisitiveness for the strange-looking black-suited creatures that visit his patch. Like many groupers, he likes to be gently patted and stroked. 

Black Grouper Bahamas (Curious George) - Melinda Riger / GB Scuba

All this curiosity and friendliness evidences a benign interspecies relationship of symbiotic mutualism, through which both species (man and fish) benefit from the interaction. The mutually beneficial feeling might in broad terms be described as ‘pleasure’.

Black Grouper Bahamas (Curious George) - Melinda Riger / GB Scuba

Or maybe I am just indulging in a bit of over-anthropomorphisation (if there is such a word)…

All photos by one half of the symbiotic mutualism here, Melinda Riger (Grand Bahama Scuba)

BAHAMAS REEF FISH (45) THREESPOT DAMSELFISH


Threespot Damselfish (Melinda Riger / GB Scuba)

BAHAMAS REEF FISH (45) THREESPOT DAMSELFISH

The threespot damselfish Stegastes planifrons is one of several damselfish types found in the Bahamas and more generally in the western Atlantic. As with so many reef species, there is a marked difference in coloration between juveniles (bright yellow) and darker-hued adults (above).

Threespot Damselfish (Melinda Riger / GB Scuba)Threespot Damselfish (Melinda Riger / GB Scuba)

These are bony little creatures, equipped with both spines and ‘soft rays’ on some of their fins. This perhaps make them unappealing to potential predators; and maybe the very brightness and ‘hi-viz’ of the juveniles is aposematic, a coloration thats acts as a warning or repellent to potential predators.

Threespot Damselfish (Melinda Riger / GB Scuba)

On the reef it seems threespots favour staghorn coral as a daytime base. Their diet is mainly seaweed, with small molluscs, gastropods and worms for variety. At night they retire to crevices and caves.

Threespot Damselfish (Melinda Riger / GB Scuba)

Adults are, for such small fish, vigorously protective of their territories. They will chase and nip intruders into their domains, even far larger creatures (up to and including humans).

Threespot Damselfish (Melinda Riger / GB Scuba)

A breeding pair will both be involved in egg care. Once the female has laid her eggs, they adhere to the lower reef and seabed. The male guards them and rather sweetly fans them with his fins to keep them oxygenated. And then another generation hatches and the threespot life cycle repeats.

Threespot Damselfish (Melinda Riger / GB Scuba)

Credits: All fantastic photos by Melinda Riger / Grand Bahama Scuba

THE ARTICULATE WHALE (2): MARINE SCIENCE ON DISPLAY


False Killer Whale Skeleton, Abaco Bahamas (Keith Salvesen / BMMRO)

THE ARTICULATE WHALE (2): MARINE SCIENCE ON DISPLAY

A couple of months back I wrote about the fate of the false killer whale Pseudorca crassidens (in fact a species of dolphin) that was stranded on Duck Cay. After its discovery, it was cut up, buried for many months before being disinterred, cleaned… and made ready to be reconstructed for display at Friends of the Environment, Marsh Harbour for research and educational purposes. The poor dead creature was destined to have a future ‘life’ (in a sense) as an exhibit. You can read the details and see the various stages of the preparatory processes (including some gory images) HERE.

False Killer Whale Skeleton, Abaco Bahamas (Keith Salvesen / BMMRO)

The FKW joint project (see below for participants) has taken more than a year. The final stage has been similar to doing a jigsaw puzzle, with the added complication that it isn’t entirely clear where or even whether all the pieces fit – there may even be one or two leftover small bones when the reconstruction is finished.

HEADFalse Killer Whale Skeleton, Abaco Bahamas (Keith Salvesen / BMMRO)False Killer Whale Skeleton, Abaco Bahamas (Keith Salvesen / BMMRO)

Since I last wrote about the ‘rearticulation’ project, I have spent some time on Abaco. A highlight was our visit to FotE to meet the jocundly-named ‘Ducky’ of Duck Cay [I’d have gone for ‘Killer’ as a name – there’s no such thing as bad publicity]. Incidentally the strange item on the whale’s skull is in fact nothing to do with the creature’s real structure – it’s a natural historian’s unicorn-related jest…

RIBCAGE & SPINEFalse Killer Whale Skeleton, Abaco Bahamas (Keith Salvesen / BMMRO)False Killer Whale Skeleton, Abaco Bahamas (Keith Salvesen / BMMRO) False Killer Whale Skeleton, Abaco Bahamas (Keith Salvesen / BMMRO)

Besides identifying all the bones and numbering them, those working on this project have had to devise ingenious methods for display to make the reconstruction as accurate as possible – not an easy task with a creature nearly 20 feet long.

SPINEFalse Killer Whale Skeleton, Abaco Bahamas (Keith Salvesen / BMMRO)False Killer Whale Skeleton, Abaco Bahamas (Keith Salvesen / BMMRO)         

FLIPPER 1 – COMPLETEFalse Killer Whale Skeleton, Abaco Bahamas (Keith Salvesen / BMMRO)

FLIPPER 2 – WORK IN PROGRESSFalse Killer Whale Skeleton, Abaco Bahamas (Keith Salvesen / BMMRO)

JAW & A TRAY OF SUNDRIES…False Killer Whale Skeleton, Abaco Bahamas (Keith Salvesen / BMMRO) False Killer Whale Skeleton, Abaco Bahamas (Keith Salvesen / BMMRO)

It would be against the principles of this blog to miss out on an obvious open goal of an opportunity for an apposite final caption…

A WHALE TALE THAT ENDS WITH THE WHALE TAILFalse Killer Whale Skeleton, Abaco Bahamas (Keith Salvesen / BMMRO)False Killer Whale Skeleton, Abaco Bahamas (Keith Salvesen / BMMRO)

This ambitious year-long project has involved BMMRO, FOTE, BEP (Bahamas Environment Protection Foundation), interns, and volunteers. A number of children from local schools have already been to visit Ducky and been completely fascinated. A dead stranded whale now has a new incarnation, and a new story to tell.

ARE STRANDINGS FREQUENT – AND WHY REPORT THEM?

Each year there may be half-a-dozen reports of cetacean strandings in Abaco waters, both whales and dolphins. As far as I can make out, the animals are almost invariably dead. If still alive, reporting is clearly urgent to ensure a quick response and to maximise the creature’s chances of survival. If dead, a carcass can provide scientists with valuable data on the biology and health of marine mammals and, in turn, the health of our marine ecosystems. This includes basic information, such as an animal’s age, its size, the types of prey it consumes, and the occurrence of diseases. Necropsies can provide more detailed information to add to the growing knowledge-base of marine mammal populations.

And a project like this one, with its great educational potential, can in effect enable a stranded marine mammal to tell its story even after death.

STRANDING NETWORK HOTLINE NUMBER +1 242 366 4155
(or +1 242 357 6666 / +1 242 577 0655)
Credits: all photos by Keith Salvesen / BMMRO. Special thanks to Olivia Patterson and all at Friends of the Environment for a fascinating time visiting Ducky Killer; and to Nancy Albury for showing us around the excellent Museum. If you haven’t been, go!

WTF? (WHAT’S THAT FISH?) 15 PORCUPINEFISH


Porcupinefish, Bahamas (©Melinda Riger / Grand Bahama Scuba)

WTF? (WHAT’S THAT FISH?) 15 PORCUPINEFISH

The porcupinefish Diodon hystrix falls into the general category ‘pufferfish’, though the particular species named PUFFERFISH are distinct in their own right. There are other similar species – e.g. balloonfish, blowfish and burrfish – with which there is scope for confusion. The relationship is something like this: all porcupinefish are pufferfish (in a broad sense); but not all pufferfish (in its species sense)  are porcupinefish. 

Porcupinefish, Bahamas (©Melinda Riger / Grand Bahama Scuba)

Porcupinefish are slow-moving reef dwellers and like their puffer cousins, they can inflate themselves by ingesting water, turning them into spiny balloons. This defence mechanism is a response to threat and works in two way: only predators with large mouths would consider them a meal; and even then they have to deal with the spines that become prominent when the fish is bloated.

Porcupinefish, Bahamas (George Parilla wiki)

I’VE HEARD PUFFERFISH ARE POISONOUS? WHAT ABOUT THIS GUY?

Good question. Checking it out, I’ve found some contrary statements about this. The truth seems to be that unlike pufferfish, they do not produce toxic secretions from their skins, so are not poisonous to touch (if you must**).

Porcupinefish, Bahamas (©Virginia Cooper / Grand Bahama Scuba)

However porcupinefish do contain powerful (neuro)toxins in their internal organs and are best not eaten – though in some parts of the world they are considered a minor delicacy. They may also suffer the ignominy of being dried in their inflated state and sold to tourists as novelties –  with lightbulbs inside for added amusement value. 

Porcupinefish, Bahamas (Bernard Dupont wiki)

ARE PORCUPINEFISH FAMOUS IN ANY RESPECT?

Indeed they are. They had the honour of being recorded by Charles Darwin. He gives a surprisingly long account of this creature, encountered during his renowned voyage on the Beagle. It clearly fascinated him. I’ve ‘ripped’ the relevant passage (open source – it’s ok) and turned it into an eezi-reed pdf if you want to check out Darwin’s careful observations in more detail:

THE VOYAGE OF THE BEAGLE – CHARLES DARWIN

Porcupinefish, Bahamas (Adam Rees / Scuba Works)

WAIT! ISN’T THERE A MORE RECENT CLAIM TO FAME?

Yes! In ‘Finding Nemo’, Bloat the Porcupinefish was part of the ‘Tank Gang’ in a dentist’s office. He had an encore in the closing credits of ‘Finding Dory’. Enough of fame already. Here’s a 50 second video demonstrating the puffer / porcupine distinction.

Porcupinefish, Bahamas (Adam Rees / Scuba Works)

RELATED POSTS
Photo Credits: Melinda Riger (1, 2); George Parilla (3); Virgini Cooper (4); Bernard Dupont (5); Adam Rees (6, 7); Video, ‘AquariumKids’ (I do high-powered research, see?)

**Incidentally, it’s apparently not considered an act of animal kindness to catch them / scare them so you can have the pleasure of watching them blow up

THE PRINCE OF WHALES: BLAINVILLE’S BEAKED WHALES IN ABACO


Blainville's Beaked Whale, Abaco Bahamas (Keith Salvesen / BMMRO)

THE PRINCE OF WHALES: BLAINVILLE’S BEAKED WHALES IN ABACO

There’s a strange affinity between humans and whales. Humans seem to think so, anyway – and whales seem to tolerate them amiably, perhaps now that the decimation of their populations by humans is (largely) a thing of the past. The Bahamas in general and Abaco in particular are in the mainstream of progressive cetacean research, led by the BMMRO at Sandy Point.

Blainville's Beaked Whale, Abaco Bahamas (Keith Salvesen / BMMRO)

One of the speciality research species is the Blainville’s Beaked Whale. These magnificent creatures are deep divers, and although they are found in many parts of the world, the Bahamas is one of only 3 locations with a significant population for study. Most of the whales here were photographed within sight of land (and a few with the Castaway Island Disney Cruise Ship visible on the horizon!).

Blainville's Beaked Whale, Abaco Bahamas (Keith Salvesen / BMMRO)

I’ve been lucky enough to be on the BMMRO research vessel on a beaked whale outing – and luckier still that we were able to spend plenty of time with a group of them, including some males. The header image is of a mature male with his huge teeth that protrude upwards from the lower jaw, and in time become encrusted with barnacles.

Blainville's Beaked Whale, Abaco Bahamas (Keith Salvesen / BMMRO)

The whales were quite undisturbed by our presence – indeed they behaved much like dolphins, circling the boat and swimming under it; moving away and returning. This was an opportunity to count the whales, to identify those that had already been recorded, and to document any new ones. Each whale has its own unique pattern of marks, striations and in some cases healed wounds. The pair below are a good example.

Blainville's Beaked Whale, Abaco Bahamas (Keith Salvesen / BMMRO)

Also, the whales have individually distinctive dorsal fins, with nicks and tears that also act as a means of identification. These can often be made out from a distance with powerful binoculars or photographed with a long lens for later analysis (this ID method also works reliably for dolphins).

Blainville's Beaked Whale, Abaco Bahamas (Keith Salvesen / BMMRO)

Beaked whales often bear the healed scars from the gouging bites of COOKIE-CUTTER SHARKS, a vicious little species that I recently featured. The distinctive circular scars on the back of the whale below result from encounters with these unpleasant creatures.

Blainville's Beaked Whale, Abaco Bahamas (Keith Salvesen / BMMRO)

Finally, the photo below. It has no merit, photographically speaking, but I love the way that sometimes a ‘risk’ shot – into the sun, perhaps – produces rather magical effects. The unexpected ‘sea stars’ were a bonus!

Blainville's Beaked Whale, Abaco Bahamas (Keith Salvesen / BMMRO)

All photos: Keith Salvesen / BMMRO