One can see many colorful sea slugs at Tatsunokuchi, a popular diving spot in the city of Nagasaki. I dove about 10 meters deep with an air tank on my back. I saw varieties such as the festive sea ...

Nudibranchs are sea slugs. They are soft-bodied animals, and like clams, snails and squid, they are mollusks. Nudibranchs belong to phylum Mollusca, class Gastropoda, order Nudibranchia.