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Why are sea squirts also called ascidians?

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Bright blue sea squirt Rhopalaea crassa with yellow-edged openings grows on a coral reef among various corals in the Philippines. — tunicate Blue spot sea squirt (*Clavelina moluccensis*), a colonial tunicate.

Sea squirts are called ascidians because they belong to the taxonomic class Ascidiacea.12

The name "ascidian" is derived from the New Latin Ascidia, which originates from the Greek word askidion. This term is a diminutive of askos, meaning "wineskin" or "bladder," a reference to the saclike body shape characteristic of these organisms.3

While "sea squirt" is a common name often used to describe these animals due to their ability to expel water through their siphons when disturbed, "ascidian" serves as the formal scientific designation for members of this class within the subphylum Tunicata.312