Sea Squirts

ocean · filter feeders · weird animals · invertebrates

Water-Sucking Bags. Sea squirts are like living water filters. They pull water in through one opening, strain out tiny food particles, and squirt the leftover water out through another opening, which is how they got their funny name.

Made of Plant Stuff. A sea squirt's tough outer skin is made of cellulose, the same material that makes up plant cell walls. This makes them one of the few animals that can produce this stretchy, protective coating.

Swimmers Turn Settlers. Baby sea squirts are tiny swimmers with tails that zoom around the ocean looking for a good home. Once they find the perfect spot on a rock or another surface, they stick there forever and lose their tail.

Stuck for Life. Once an adult sea squirt settles down, it never moves again. It spends the rest of its life in one place, attached to rocks or the ocean floor, quietly filtering food from passing water.

Surprising Smart Babies. Larval sea squirts have a simple brain and a tiny spine-like structure, making them one of the few invertebrates with something like a backbone, but they lose both as adults.