Ascidiota

Ascidiota is a taxonomic group within the animal kingdom, specifically referring to a suborder of tunicates, also known as sea squirts. Tunicates are marine invertebrates belonging to the phylum Chordata, a group that also includes vertebrates. The characteristic feature of Ascidiota is the presence of a leathery or gelatinous outer covering called a tunic, which is secreted by the animal's epidermis. This tunic is unique among living organisms and is composed primarily of tunicin, a cellulose-like polysaccharide.

Members of Ascidiota are sessile filter feeders, meaning they attach themselves to a substrate, such as rocks, piers, or other marine organisms, and strain food particles from the water. They possess two siphons: an oral siphon through which water enters, carrying food and oxygen, and an atrial siphon through which water, waste, and gametes are expelled. In their larval stage, ascidians exhibit a notochord, which is a defining characteristic of chordates, although this structure is lost in the adult form.

Ascidiota are found in all marine environments, from shallow coastal waters to the deep sea, and are globally distributed. They play important ecological roles in marine ecosystems, contributing to water filtration and serving as a food source for various predators. Their life cycles typically involve a motile, tadpole-like larva that disperses before settling and metamorphosing into the sessile adult. This group encompasses a wide diversity of forms and sizes, some living solitarily and others forming colonial structures.