Sunday, 15 August 2010

Frilled Shark

Image source
Wow! We have something of a mini Leviathan this time, folks! It's a shark, but with little in common with what we have thus far grown accustomed to be denoted by the term. Jim. Basically, they're a bit weird. With its snakey head and eely body, fins set far back on the body, it's no wonder that the frilled shark is believed to be at the root of sea serpent sightings, even though it only grows to around 2 metres long. I mean, it's hardly gonna sink ships, is it?

But what the frilled shark lacks in stature it makes up in mystery and eccentricity. It isn't just odd, its an ancient among the ancients, a living fossil amidst the long and diverse line of shark heritage. With this old age comes a host of peculiarities that some may see as primitive, but which seem to serve this psuedo serpent sssswimmingly! (I have a smile on my face now!)
The frilled shark has been accidentally caught by trawlers in many scattered locations around the Pacific and Atlantic oceans (it's not common, but it seems to get around a lot), whilst specimens found around southern Africa have turned out to be a similiar, but different, species. It has been caught at depths of 1,570 metres (5,150 feet, very deep!) but it seems to prefer to stay above 1,000 m (still deep!).

It must have some of the weirdest teeth ever. They're shaped like little tridents (like Neptune... or Satan) arranged in about 25 seperated rows on both the upper and lower jaw. This means that each individual tooth has three needle sharp cusps of cutting, and there are some 300 of these teeth in its gob. This leaves the possibility that anything the frilled shark bites could literally suffer 'death by a thousand cuts', which gives me a certain satisfaction. Scant comfort for the unfortunate victim though I'm sure. In any case, the usual recipient of this treatment is obviously FOOD, mostly squid, but also fish and other sharks. Those teeth are particularly useful for snagging the soft bodies of squid, some even think that bright teeth surrounded by dark waters, grey or brown shark skin and the black abyss of shark throat and shark stomach, confuses the squid to start attacking the pearly whites... with disastrous results.

No-one has actually seen the frilled shark attack or eat anything, though. Some propose that it might arch back and suddenly lunge forward like a snake, surprising its prey since it doesn't have a powerful bite. It's known to somehow find and somehow catch surprisingly powerful, fast swimmers, and with its expandable mouth and gigantic gape, the frilled shark can swallow whole creatures more than half its own size.

Some of this might be familiar to other deep sea fish, but the frilled shark seems to spend a fair amount of time in shallower waters. It seems to migrate to the surface quite often, maybe very often, ascending over 1,500 metres, apparently to feed. Examining the contents of their stomach is tricky because of the advanced state of digestion; perhaps the frilled shark eats so often that it has to digest it quickly, or maybe it seldom needs to eat at all.

Like all fish, it has a lateral line running along the side of its body, bristling with tiny hairs that can detect vibrations in a manner similar to the inner ear. The frilled shark's lateral line is open to the surrounding water though, it doesn't use pores like most sharks do. Perhaps this increases sensitivity to even the tiniest of movement, a great advantage in the darkness of the deep sea where many creatures conserve energy by keeping themselves to the tiniest of movements.

Even its skeleton is poorly calcified so it doesn't need quite so much nutrition (pints of milk are uncommon down there), while its massive liver allows it to maintain position easily without sinking or needing to constantly swim like other sharks (most fish use a swim bladder to control buoyancy, sharks use their large liver).

Then there are the actual 'frills'. Most fish have their gills neatly and aerodynamically hidden under smooth gill covers. This shark on the other hand has an unusual frilly appearance. Its unknown what purpose this may serve, but it has been posited that closing these gills may create a vacuum that could suck prey right into its mouth. Easy!

The frilled shark also has an extraordinarily long gestation period estimated at 3.5 years. That's some 42 months of pregnancy! By far the longest of any vertebrate. The mother gives birth to around 6 live pups (between 2 and 15) when they reach 40 to 60 cm in length, after protecting the eggs in her body.

Phew! I'll finish up by saying: if you've seen the video of the sick and dying frilled shark around Japan (and I suspect you have), then take a look at this picture of a fine specimen in its natural environment. Sleek and refined, spooky and mysterious, a master of no-one knows what. Almost 3,000 feet into the deep sea, surrounded by temperatures scarcely above freezing. The frilled shark still manages to keep its secrets and who knows? Perhaps there may yet be a relative, another species of frilled shark of such size and power as to be a real sea serpent, a true Leviathan of the Abyss. If there is, you can be sure it will appear on Real Monstrosities. When I get round to it.


You know, I had thought that "death by a thousand cuts" was from Shakespeare or something, but now that I actually look it up... it's horrible!   


Parag said...

The Frilled Shark is a primitive shark species, sometimes called a "living fossil" because it resembles extinct species of sharks. Frilled sharks are usually found at depths of around 2,000 feet, but this one somehow found its way into shallow water off the coast of Japan, where it was captured and taken to a nearby marine park.

Comment1 said...

Quite so!

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