Nudibranchs of Vanuatu

On October 8, 2008, Vanuatu Post issued the stamp features the jewels of sea, Nudibranch. The stamp issued in one miniature sheet consist of 12 single stamps which each stamp depicts species of nudibranchs and composed in one beautiful colour scene of bottom the sea

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The 3,000-plus known nudibranch species are possibly the most colourful creatures on earth. In the course of evolution, these “sea slugs” have lost their shell developing other defence mechanisms. Nudibranchs are blind to their own beauty, their tiny eyes discerning little more than light and dark. Instead the animals smell, taste and feel via oral tentacles. Chemical signals help them track food—not just coral and sponges but barnacles, eggs, or small fish - and other nudibranchs.

As members of the gastropod class, and more broadly the molluscs, they live fully exposed at virtually all depths of salt water, their gills forming tufts on their backs. Varying in adult size from just 20 to 600mm, they reach their greatest size and variation in warm, shallow waters and are found extensively on Vanuatu’s many reefs.  Hermaphroditic, nudibranchs have both male and female organs and can fertilise one another, an ability that speeds the search for mates and doubles reproductive success.

 

Nudibranchs are carnivorous. Some feed on sponges, others on coral animals (hydroids) and some are cannibals, eating other sea slugs, or, on some occasions, members of their own species. There is also a group that feeds on barnacles and occasionally anemones.  Some nudibranchs rely on enzymes, rather than teeth, to break down prey. In turn they are also the prey of certain fish, sea spiders, turtles, sea stars, a few crabs.

They are well equipped to defend themselves however. Tough-skinned, bumpy and abrasive, some are able to camouflage, however, others have bright colouring making them highly visible. This warns they are distasteful or poisonous. Nudibranchs hoard capsules of tightly coiled stingers, called nematocysts, and automatically release a sour liquid from the skin when touched. .(Resources: Vanuatu Post)

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