tornaria larva

A tornaria is the free-swimming larval form of an acorn worm, which is a type of marine invertebrate belonging to the group known as enteropneusts. These larvae resemble the bipinnaria larvae found in echinoderms. Echinoderms, such as sea stars and sea urchins, also have larval stages that are part of the plankton and feed on small organisms before metamorphosing into juvenile forms. While some flatworms have simple life cycles with free-swimming larvae, parasitic flatworms undergo complex cycles with multiple larval stages in intermediate hosts. The tornaria larva is a crucial stage in the life cycle of acorn worms, enabling dispersal and development.123