The body is cylindrical, 10 to 20 centimeters long, and extra-large up to 30 centimeters, usually dark black in color, with many fleshy spines. The tentacles are whorl-shaped, 17 to 30, about 20. Tentacles and hand altar sacs are well developed.

The vast majority of sea cucumbers have bony plates, table-shaped, buckle-shaped, rod-shaped, perforated plate, pattern-like, whorl-shaped, anchor-shaped, cage-shaped and other shapes; the number varies, an ugly sea cucumber has about 20 million bony plates, while the sea geoducks are sometimes all bony; the sea cucumbers that have more bony plates are rough to the touch, while those with fewer bony plates are smooth; the bony plates are a kind of monocarious endoskeleton, which is reduced to small bony plates.

The unique organ of the sea cucumber is the lime ring, which supports the pharynx, the nerve ring, and the water pipe of the ring; it is generally composed of 5 spokes and 5 inter-spokes; the lime ring of some sea cucumbers in the order of branchiopods consists of a mosaic of most of the small slices, and each spoke extends backward with a forked prolongation; the lime ring of the order of the anurans is generally more than 100 slices.

The sea cucumber has a gonad, located on one or both sides of the mesentery, and a common duct opens between the tentacles in the dorsal midline or slightly behind them. The "coral mussels" sold in seafood markets are actually the leftover edible parts of these intestines after they have been cleaned out, and are one of the ingredients in hot pots.

Expanded information:

1, habits

When the water temperature reaches 20 degrees Celsius. Spiny ginseng will transfer to the deep sea in the crevices of the rocky reef or submerged in the rocky bottom, do not eat, the whole body contraction hardened as a spiny ball. General animals will not eat it. It sleeps for a summer and wakes up in the fall to resume its activities.

2, growth and reproduction

In order to ensure that the race will not be extinct, in the process of long-term natural selection and evolution, the sea cucumber possesses a superb reproductive ability. An adult sea cucumber over 4 years old can ovulate about 5 million eggs at a time during the spring breeding season. This ensures the continuation of the race even if there is a 1 in 10,000 survival rate.

Baidu Encyclopedia-Sea Cucumber