Black Sea Cucumber (Holothuria atra)

In Japan, it is commonly seen on the coral reef areas of the Kii Peninsula and southwards. It is a medium-sized sea cucumber reaching a length of 20 to 30cm. The body is elongated with conical bumps on the surface of its body. When threatened it expels Cuvierian tubules, a sticky, white, thread-like substance, from its anus.