Friday, October 15, 2010

Creature Feature: Giant Clam.

Bivalves are cool. They make pearls. They look good and they taste good (well, to some people). Their shells are darn awesome, but not quite as awesome as some snails. Never has a bivalve seen the light of this blog...until now.

Meet the giant clam (Tridacna gigas). Its name says it all: This clam is the largest extant bivalve known to man. It is native to the South Pacific (they have more awesome fauna where this came from), and, owing to its great size, often carries a lot of stories with it. It is one of the most endangered clam species.

That's not an eye, it's a siphon. Really.

A little primer on bivalves: All bivalves, clams included, start their lives as little larvae called glochidia. These are mobile little critters that look an awful lot like Pac-Man would if he ever made a heavy metal album:

Those teeth are for latching onto fish, not eating your soul.

The giant clam goes from being a motile little Pac-Man larva to a sessile, gigantic clam. How big are we talking? The shell of the largest giant clam was 115 cm long, and it is estimated that the live weight was around 734 pounds (340 kg).

It's a clam and it's giant!

Along with being the world's largest clam, the giant clam produces the world's largest pearls. The largest pearl on record, the Pearl of Lao Tzu, was given to Wilburn Cobb by a Philippine chief in 1939. This pearl is 24 cm's in diameter and weighs 6.4 kg (9.45 pounds). Later, Cobb told a story about how the pearl was cultivated in successively larger clams until it reached this massive size. Since its discovery, it has been dubbed "the Pearl of Lao Tze" and "the Pearl of Allah." It currently resides in the private collection of Victor M. Barbish, so should you ever desire a giant calcified bird dropping, you know who to go after.

You would have to be an eccentric billionaire to want it to begin with, really.

The giant clam gets its food from the algae growing in its shell. Every so often, it opens its shell to let the algae photosynthesize. These algae are what allow it to get so big; hey, if Popeye could not convince you that veggies were a good thing, perhaps a giant clam can.

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