Chordates: Tunicates & Ascidians

This subphylum is more closely related to humans than any other invertebrate phylum. They posess a rudimentary notochord in their larval stage.

Tunicates and ascidians are jelly-like, soft-bodied animals that take in water through a siphon, filter it for food, and then expel the water back into the sea through another siphon. There are ninety species in the Pacific Northwest. They are covered in a tough cartilage-like substance called a tunic, which varies in color and toughness between species. In the Northwest, they are either fuzzy-looking, translucent and knobby, or completely transparent.

Tunicates have a heart that can reverse its pumping every few minutes and change the direction of bloodflow, and their blood contains levels of vanadium that are up to one million times that of the surrounding seawater. The advantages of these adaptations are currently unknown.

(click on photo to enlarge)
	Hairy tunicate (Boltenia villosa)
	Orange social tunicate (Metandrocarpa taylori)
	Sea vase (Ciona savignyi)
	Shiny orange sea squirt (Cnemidocarpa finmarkiensis)
	Transparent tunicate (Corella willmeriana)