| Holothuriidae, Holothuria, Stichopodidae, Apostichopus japonicus|
Aspidochirotida is an order of sea cucumbers.
They are distinguished from other sea cucumbers by the presence of flattened, often leaf-like tentacles, but without the other large appendages found in the related order Elasipodida. They do not have introvert or retractor muscles. The tube feet often form a clearly demarcated sole. They have 15-30 shield-shaped retractile tentacles surrounding their mouths. The body wall is thick and leathery and contains ossicles, including some table-shaped ones. They have respiratory trees for gas exchange. The mesentery of the posterior loop of their gut is attached to the right ventral interradius. The muscles that run longitudinally down the body are arranged into five double bands. They can shoot out sticky white threads known as cuvierian tubules from their cloacas in order to distract or entangle predators. They are usually found in exposed shallow-water environments.
Their popularity as luxury seafood in some Asian countries poses a serious threat to the order.family Holothuriidae Burmeister, 1837 -- 5 genera, 200 species
family Mesothuriidae Smirnov, 2012 -- 2 genera, 32 species
family Stichopodidae Haeckel, 1896 -- 10 genera, 34 species
family Synallactidae Ludwig, 1894 -- 18 genera, 122 species