Molpadida is an
order
Order, ORDER or Orders may refer to:
* Categorization, the process in which ideas and objects are recognized, differentiated, and understood
* Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...
of
sea cucumber
Sea cucumbers are echinoderms from the class Holothuroidea (). They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. The number of holothuria ...
s. The body shape is
fusiform
Fusiform means having a spindle-like shape that is wide in the middle and tapers at both ends. It is similar to the lemon-shape, but often implies a focal broadening of a structure that continues from one or both ends, such as an aneurysm on a b ...
and unlike other sea cucumbers, their hind body is narrowed to form a distinct tail. Although they possess tentacles around the mouth derived from the
water vascular system, they have no true
tube feet, and are therefore believed to be related to the
Apodida.
They have fifteen much branched tentacles and a stout body. They have tentacle ampullae and respiratory trees present, a kind of water lung attached to the cloaca. The
ossicles
The ossicles (also called auditory ossicles) are three bones in either middle ear that are among the smallest bones in the human body. They serve to transmit sounds from the air to the fluid-filled labyrinth (cochlea). The absence of the auditory ...
, minute calcareous plates embedded in the skin and characteristic of each species, take the form of tables, anchors, fusiform rods and perforated plates but never wheels.
An illustrated key to the sea cucumbers of the South Atlantic Bight
Retrieved 2012-02-12.
Like their relatives, they are adapted for burrowing into soft sediment, but they are relatively sedentary, rarely moving once they have excavated their burrow. Their burrow is U-shaped, with the animal's tentacles projecting from one end.
Notes
References
*
Echinoderm orders
Taxa named by Ernst Haeckel
{{Holothuroidea-stub