Sea squirts are filter feeders, often found near coastal areas. Their transparent outer body gives them the appearance of a sponge or plant, but they're actually marine animals.
As NOAA celebrates "30 Days of the Ocean" in June, we take a look at some of these bioluminous, stunning underwater finds.
Free-swimming in the larval stage, adult sea squirts take root by attaching to coral, rock, shells or another hard surface.
There are about 2,300 species of sea squirts, and though they are solitary creatures they form colonies that can be several meters wide.
They are are also, to some folks, pretty tasty. Above, sea squirts go on display at a market in Korea.
Sea squirts have two "siphons" at the top of their body -- one to suck in water and one to, well, squirt it out. Above, a light bulb sea quirt (Keulenseescheide Ascidia) handles its business.
The sea salp is not a sea squirt, but it is a species of tunicate, and no slouch in the bioluminescence department.
Here you can see the flow opening of a red sea squirt (Halocynthia papillosaut).
Sea squirts can grow up to 7 inches (18 centimeters) in diameter and are also able to heal damaged parts by regenerating cells.
The sea squirt's healing abilities have prompted researchers to study them, with the hopes that they might help cure diseases such as Alzheimer's and heart disease in people.