Friday, February 20, 2009

Goblin girl on… size!

Does size matter? At least when it comes to sharks it seems like size matters. One of the most frequently asked question I get from the public is: which is the smallest and which is the largest shark? It is quite uninteresting in one way. I mean, the maximum length for a human is 2.72 m (8 ft 11 in). How many people have been that tall? One! So, maximum length might be interesting for anecdotal reasons, but it doesn’t say much on the ”ordinary” shark. Still, it is a very common question and therefore I can’t ignore it.

The late Aidan Martin held the dwarf lantern (Etmopterus perryi) as the smallest shark. It reaches a maximum length of ca 20 cm (8 in) according to fishbase . At a size of just 19 cm one female was carrying developing embryos. After sharks reach sexual maturity the growth rate slow down considerably. Therefore the size at sexual maturity is interesting.

It was also to fishbase I went in search for the largest whale shark on record. I was a bit amazed to see a total length of 20 m (66 feet). I would have said 14 m (46 ft), and usually fishbase is quite conservative when it comes to size. So I posted my question on the three sharky mailing lists I’m a member of.

Luckily one list-member was in direct contact with Professor S.J. Joung in Taiwan - one of the authors to the fishbase referene. He assured the member that he personally witnessed this shark - and although not accurately measured, the animal was estimated by him and his scientist colleagues (Profs. Chen & Liu) at 20 m TL. The shark weighed 43 t!

The length equals that of the largest toothed whale, the sperm whale , where the bulls can grow to 20.5 m (67 ft) and weigh 57 t. Note that the whale sharks cartilage skeleton makes it much lighter, if not light!

So, does size matter? Let me know what you think!


Sandy said...

Interesting post. Is there not a smaller parasitic shark that lives in deep water?

2 cm?

Charlott - the Goblin girl said...

I haven't heard about any parasitic shark that small. The cookie cutter shark is the one that comes to mind from your description, but the grow to around 50 cm.