The KITAN CLUB 2012 Sea slugs set walkaround

Nudibranchia is a group of soft-bodied, marine gastropod mollusks which shed their shell after their larval stage. They are noted for their often extraordinary colors and striking forms. There are more than 3,000 described species of nudibranchs.
Nudibranchs are often casually called sea slugs, but many sea slugs belong to several taxonomic groups which are not closely related to nudibranchs. A number of these other sea slugs, such as the colorful Aglajidae, are often confused with nudibranchs.
Nudibranchs occur in seas worldwide, including both the tropics and Antarctica. They live at virtually all depths of salt water, from the intertidal zone to over 700m. Their greatest size and variation is in warm, shallow waters.
Nudibranchs are benthic animals, found crawling over the bottom substrate. An exception to this is the Glaucilla nudibranchs, which float upside down just under the ocean's surface. Another exception is the pelagic nudibranch, Cephalopyge trematoides, which swims in the water column.
Their eyes are simple and able to discern little more than light and dark. The eyes are set into the body, are about a quarter of a millimeter in diameter, and consist of a lens and five photoreceptors.
They vary in adult size from 20 to 600 millimetres.
This group includes some of the most colorful creatures on earth. In the course of evolution, nudibranchs have lost their shell because they have developed other defense mechanisms. Some species evolved an external anatomy with textures and colors that mimicked surrounding plants to avoid predators. Other nudibranchs have an intensely bright and contrasting color pattern that makes them especially conspicuous in their surroundings. The shocking coloration warns potential predators that the slugs are distasteful or poisonous.
Nudibranchs use a variety of chemical defenses to aid in protection, but it is not necessary for the strategy to be lethal in order to be effective: some successful toxins induce bradycardia or hypotension in a predator, allowing the nudibranch to escape consumption while its attacker is incapacitated.
They are hermaphroditic, and thus have a set of reproductive organs for both sexes, but they cannot fertilize themselves.
All known nudibranchs are carnivorous. Some feed on sponges, others on hydroids, others on bryozoans and some eat other sea slugs or their eggs or, on some occasions, are cannibals and prey on members of their own species. Other groups feed on barnacles and anemones.
The surface dwelling nudibranch, Glaucus atlanticus is a specialist predator of siphonophores, such as the Portuguese Man O' War. This predatory mollusk sucks air into its stomach to keep it afloat and using its muscular foot it clings to the surface film.

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