sea squirt

American  

noun

1. any tunicate, especially a sessile ascidian, so called from its habit of contracting its body and ejecting streams of water when disturbed.

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sea squirt British  

noun

1. any minute primitive marine animal of the class Ascidiacea, most of which are sedentary, having a saclike body with openings through which water enters and leaves See also ascidian

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sea squirt Scientific  

1. Any of various tunicates of the class Ascidiacea, having a transparent sac-shaped body with two siphons. One of the siphons is used to draw water (carrying oxygen and food particles) into the body, while the other expels it. Sea squirts are free-swimming as larvae but sessile as adults. Like other tunicates, sea squirts are chordates, but they have a notochord only in the larval stage.

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Etymology

Origin of sea squirt

First recorded in 1840–50

Example Sentences

Unlike the sea squirt, both the lamprey and the frog produced many more versions of proteins from individual signaling output genes.

From Science Daily • Feb. 4, 2026

Collecting DNA traces from water samples, they show some invasive species are thriving, including a sea squirt that is believed to have originated in Japan and which grows like a carpet over the sea floor.

From BBC • May 7, 2024

Krogan is especially keen on one, plitidepsin, which comes from a species of sea squirt found only in the waters off the Spanish island of Ibiza.

From Washington Post • Oct. 31, 2022

Once it has found a suitable home, like, say, a nice secure rock with plenty of organic food just flowing by, the sea squirt will attach itself with its head facing out.

From Slate • Oct. 30, 2014

That is, the sea squirt begins life as a primitively simple vertebrate.

From Composition-Rhetoric by Brooks, Stratton D.