Sunday 10 June 2012

Zebra Shark

Image: sigkyrre via Flickr
Zebra? This podgy faced layabout looks nothing like a zebra! Cake-eating Shark appears far more appropriate... We shall have to get to the bottom of this.

Image: CW Ye via Flickr
OK, OK... our rosy cheeked friend isn't so bad. While his days are spent lounging on the sea floor and occasionally going for a sluggish swim - much like any of us on holiday - his nights are full of activity and quite devoid of deep sleeps on hotel beds. Let alone room service.

This is Stegostoma fasciatum, a carpet shark who has a wide coastal range from South Africa to India, and southeast Asia to Japan and northern Australia.

They are in fact one of the mighty Whale Shark's closest relatives, a fact suggested by the similar body shape and the same 5 ridges running down the body.

Image: Robertson, D Ross
However, at a mere 2.5 metres (8.2 ft) in length, the Zebra Shark is certainly a runt compared to their gigantic cousin. They also lead a completely different lifestyle and have a peculiarly long tail fin. Or maybe half a tail fin, since the upper lobe runs along almost half the body while the lower lobe is scarcely there at all.

Despite their chubby features, Zebra Sharks are ruthless, nocturnal hunters.

They swim well by wriggling their body like an eel. They are agile and flexible, allowing them to get deep into the crevices of rocks and reefs. Once they discover something juicy cowering in the corner of an erstwhile hiding place, the Zebra Shark sucks them up into their tiny, little mouth. They can do that because of all the muscle they have in their rotund cheeks.

Bah! You just can't tell plump from muscle with some people!

These attentions are lavished mostly on shelled molluscs, though they will also take crustaceans and fish. This would be a terribly rude awakening for anything that snoozing in their hidey-hole at night. Someone tried to get the Zebra Shark to sleep with the fishes, but he decided to stay up and eat them instead.

Is that why the Zebra Shark has spots? Is this some kind of witness protection programme? Are they on the lam?

We'll have to look at reproduction to find that out.

It all starts when a male Zebra Shark starts chasing and biting his chosen belle. I've never tried this approach with the ladies. Never had a broken nose, either. Yet, for the Zebra Shark it works at least sometimes. Trust a shark to turn kiss chase into bite chase.

Things are going well when a male holds onto a female's pectoral fin and they sink to the sea floor and do absolutely nothing. Sounds quite romantic. Alas, doing nothing must give way to doing something for a few minutes and then she's pregnant.

Females lay about 4 eggs at a time. They're pretty big, at around 17 cm (7 in) long and half that across. They have sticky fibres on the sides that get them stuck to the seafloor. They hatch after about 6 months, revealing a baby shark some 30 cm (1 ft) in length.

And what does this baby shark look like?

Image: John E. Randall, WorldFish Center - FishBase
Baby Zebra Shark earning its name

A Zebra Shark! A real, proper, zebra kind of Zebra Shark! It looks so different from the parents that it was long thought to be a completely different species.

Image: Wikipedia
Juvenile. Or a spotty teenager.

They even have to go through a difficult adolescent stage where they're not quite adult and not quite child.

They'll never grow out of bite chase, though.


TexWisGirl said...

thanks for showing the baby! as for fat vs. muscle, i think lots of folks say you can't tell the difference. :)

Joseph JG said...

That's my excuse!

And no way could not show that baby. It's a beauty!