Chitons

Similarly like limpets, a strange mollusc called chiton lives at rocky sea shores, mostly at places which are exposed to considerable turbulence. It is not a snail - instead, it forms a group of its own within the Phylum Mollusca, called the Class of Polyplacophora. This strange animal has an armor-plated back as a protection against the sea or other dangers, which is formed by eight flexibly jointed, shell-like plates, instead of just one shell.

Like a little knight among shore molluscs, it moves very slowly over the rock and scrapes algae from the surface. The plates are surrounded by a girdle of soft body tissue, which can be of very different texture, according to species. Some species have smooth or spongy girdles, others have more rough ones, covered with reptile-like scales, hairs or even spines. Also the color and texture of the plates varies considerably among species. Because some of these plates are very beautiful, chitons have also risen the attention of shell collectors. However, these shells can basically only be collected from live animals, making it necessary to kill them for preservation.

The animal's body is extremely flattened. With its broad foot, it has considerable strength to remain attached to the ground. People could only remove it with the aid of a knife. But if it ever gets loose, this is rarely a problem: The loosened chiton simply rolls its armored body to a ball, being perfectly protected by its plates - like woodlice do.

Chitons are extremely sluggish, and in direct sunlight during the day, they might not move at all. During the night, they are usually more active. There are male and female individuals, and they reproduce by releasing sperm into the water, which the female animals suck up to fertilize their eggs. The larvae are also released into the water, but develop directly into miniature adults and settle down on a rock.

Interestingly, chitons have several eyes just like some mussels. These tell them when they arrive in the shadow of a safe crevice, i.e. whether their environment is dark or bright. The numerous eyes are one of several major differences that chitons have in comparison to snails, which have two eyes. They are regarded as a more "primitive" form of life than snails.

Some chiton species are extremely well camouflaged, or even overgrown with algae and lichens, so it might be hard to find them. Other species are relatively well visible, at least in times of low tide. There are about 1000 species of chitons worldwide, mostly living at sea shores. However, a few exceptional species are found in deep sea areas, the deepest in around 4200 metres depth.

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