Friday, April 29, 2005

Redang... the Nudibranch

Nudibranch grazing on a coral head

'Nudus' is Latin for naked. 'Branchia' is Greek for gills.

Marry these two, you get Naked Gills.

Why the need to marry Latin with Greek, I don't know.

In more down-to-earth lingo, these creatures are sea slugs, or sea snails, without the shell.

They don't really breathe through gills, but rather through that protruding opening that looks quite a bit like a flower bud about to open.

Unlike those ‘uninteresting’ terrestrial slugs that chew up your garden vegetables, these guys are some of the most colorful creatures you can ever find in the oceanic realm.

I love to seek them out because they don't swim away when I shoot them; not like those coral fishes that can't keep still even for a 10-second photo session.

Most nudibranches have rhinophores (tentacles, or horns) that are sensitive to touch, taste, and smell.

They are hermaphroditic (meaning that, they contain both the male and female sexual organs at some point during their lives), but cannot fertilize themselves.

So, they still need to look for a willing partner to 'do' it.

And can you imagine that these tiny fellows are also carnivorous? With their diet focusing on sponges, hydroids, tunicates, and even barnacles? (More pictures of these later, if I don't forget)

Why the colors? One theory: self-defense.

The color camouflage makes them blend into the environment as well as to warn potential predators that their meat is distasteful or even poisonous.

This nudibranch that I shot at Redang is called Chromodoris bullocki Colingwood. Quite a mouthful of a name.

Although this family of nudibranch comes in several color variants, this particular specimen is light pink and has a thin white marginal line on the sides.

The gills are whitish while the rhinophores are yellowish.

They dwell openly in shallow reefs and their size ranges from 4 mm to 60 cm.

I once saw a bright yellow-blue colored 'pajama' nudibranch (another specie of the larger Chromodoris family) while hunting for mussels in the Japan Inland Sea near my home. Right on the pebbles at the edge of the sea.

So, if you are lucky, you don't need to go diving to see them.

The guy in this photo is about two centimeters.