Alien  Earthlings
Sea Cucumber

Sea cucumbers, or holothurians, are marine invertebrates with elongated, cylindrical bodies covered in soft, leathery skin resembling the fruit of a cucumber plant.1They are related to starfish, sea urchins, and feather stars and belong to the class Holothuroidea, one of the five extant classes within the phylum Echinodermata.

As echinoderms, sea cucumbers exhibit pentamerous radial symmetry (though not visible from outside), possess specialized tube feet for locomotion, and have up to 30 oral tentacles for gathering food.2 Their calcareous endoskeleton consists of microscopic ossicles, which sometimes form larger plates, giving them a scaly appearance.

They are found worldwide, primarily as benthic organisms attached to sediments on the ocean floor.3 They feed by scavenging debris and consuming plankton from the water.

Currently, around 1,786 recognized species of sea cucumbers are classified into two extant subclasses and seven orders.