With less than a month left in 2012, the New Year is fast approaching. The zodiac animal for next year is the snake. Therefore, Tokyo Sea Life Park "Tokyo Sea" area has started an exhibition featuring brittle stars, creatures associated with snakes.

So, what is the relationship between brittle stars and snakes? The long, slender arms of brittle stars are likened to a snake's tail, and the scientific name for the group of brittle stars (class Ophiuroidea) is Ophius = snake, ura = tail, oid = like. For this reason, brittle stars are also called "snake-tailed fish." Furthermore, the scientific name for the family Gorgonocephalidae, which belongs to the same group of brittle stars, is named after the Gorgon, a monster from Greek mythology who had living snakes growing out of her hair.

Among the species displayed this time, the red brittle star, the large brittle star, the black brittle star, and the spotted brittle star are all brittle stars with the basic form, possessing five arms.

On the other hand, the Cenotezurumozuru, with its strange appearance resembling intertwined vines, appears to have many arms, but upon closer inspection, it becomes clear that, like other brittle stars, it has five arms extending from its central body, with the ends branching out in succession. In the aquarium, you can observe up close how it occasionally moves these arms slowly.

Brittle stars are creatures with a disc-shaped body (disc) and typically five arms, rarely six. The mouth is located in the center of the underside of the disc, and inside this mouth is only a sac-like stomach; this mouth also serves as the anus.
Brittle stars live on the surface of the seabed, burrowing into shadows and sand, and some also wrap themselves around other animals such as sponges and corals. They inhabit a wide range of environments, from shallow to deep waters, and are creatures with rich variations in size, body color, and patterns depending on the species.
Their diets are diverse, ranging from fine nutrients floating in the water and seabed sediment to carnivorous and carrion-eating species that hunt prey, and many species even utilize different diets depending on the situation.
The arms of a brittle star are made up of a series of small bony plates that can bend freely, allowing them to move skillfully when catching prey and bringing it to their mouths, or when moving quickly.

The brittle stars in the aquarium become active at night, but during the day they tend to hide in the shade, often seen with only their long, slender arms extended outwards. Do these arms resemble a "snake's tail"? Try comparing different types of brittle stars.

Photo above: Black brittle star
Photo: Arms of a black brittle star extending from behind an object.
Photo below: *Cenotaphus japonica*

[Tokyo Sea Life Park]

(December 14, 2012)