Phylum Chordata Class Ascidiacea Number of families 24
Benthic, solitary, and colonial species whose adults are sessile, almost exclusively fixed, firmly attached, or lying free on the sea floor; they usually filter feed; larvae are free swimming
Photo: These tunicates (Phallusia julinea) have a larval stage with notochord, forerunner of the vertebrate spine. (Photo by ©David Hall/Photo Researchers, Inc. Reproduced by permission.)
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