Sunday, 20 May 2012

A Sea Slug Symphony


The nudibranch is a soft bodied marine gastropod mollusk – but many people simply refer to them, perhaps somewhat unfairly, as sea slugs.  You can see why they gained this nick name (even though it is often taxonomically inaccurate too!) but compared to the land bound version they are an explosion of color and grace.  Here are just a few of the 3,000 species.

This beautiful creature is found in the Western Pacific. A rich pinkinsh purple color, they have a white border on their mantle. They would be startling enough without, but their rhinophore clubs are an orange-yellow color that is a startling juxtaposition with the rest of their bodies. This exquisite creature is formally known as Hypselodoris apolegma.

This is Flabellina iodinea, an elegant species if ever there was one. It is also known as the Spanish Shawl because of its rich purple coloring. You can find it from the West Coast of America all the way to the Galapagos islands. The rhinophores – what we might call its horns – are used to find possible mates and its prey as well. The appendages you can see are actually gills which draw oxygen from the sea water.

Glossodoris atromarginata is found off the coast of Australia. It has a black line along the border of its mantle edge which gives it an almost modern art look. Its gills often wave in a rhythmic motion as it moves, giving the sea slug an other-worldly quality which has to be seen to be believed. It can reach six centimeters in length and is the most common species in its group.

The Hammerhead Nudibranch is a specialty in some parts of the world and you can see why it might be found attractive. A gorgeous black color with vivid, almost neon markings around its mantle, this could perhaps also be named as the Prince of Darkness of the nudibranch world. Its Latin name is Chelidonura varians and its dark beauty is a perfect contrast to the vivid brightness of other sea slug species.

Tritonia festiva, as this gorgeous specimen is known, can be found from Alaska to northern California and can be even found in the waters off Japan. Its food is the soft coral called gorgonians. Their frontal veil is used to position itself over these soft corals and then it waits to launch a surprise attack. It attacks its prey very quickly and bites off polyps before they can get back in to their protective cover. So, it may look like a delicate and peaceful creature but it is far from it!

You really would be forgiven for thinking that this is a creature recently discovered on another planet by one of the Star Trek crew. However, it is in fact Janolus barbarensis and this fabulous creature is distributed from California down to Mexico. It is named for its proximity to Santa Barbara and is in fact one of two incredibly alike species that for a time were considered the same.

These two strikingly different looking specimens are in fact the same species. Hermissenda crassicornis can look quite different and these color variations are in fact quite common. The white lines on the species can also appear blue. How they tell that they are the same species is anyone’s guess.

This is Hypselodoris bennetti and can be found off the coast of New South Wales in Australia. It can grow up to about five centimeters but is normally somewhat smaller than that. The spots are arranged randomly, so each one is unique. It is often thought to live a distance from its food, but the sponge it lives off is covered over with algae, hence the mistaken belief.

This is the aptly named Chromodoris magnifica – and so it is indeed. The name means magnificent colors and as you can see this denizen of the sea is truly gorgeous. It is from Indonesia, Australia and Papua New Guinea and feeds off red sponge. It lives in depths of about five meters and can be found as deep as thirty.

A translucent species, Chromodoris lochi has several dark bluish or black longitudinal lines that set it apart from other species. This sea slug lifts itself up and seems to be “sniffing” around. They are hermaphrodites and as such have fully functioning female and male organs. So, this species produces both eggs and sperm. When mating they position themselves by the side of another and align their genitalia to enable the passage of sperm.

First Image Credit Flickr User divemecressi

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