BIOL 1010 Lecture Notes - Lecture 54: Tunicate, Chordate, Notochord
14 May 2017
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Document Summary
Tunicate & lancelet are both invertebrate chordates due to not having a backbone. Food particles are trapped in net made of mucus & transported to intestine, where digested. Because they shoot jet of water through excurrent siphon when threatened, tunicates are often called sea squirts. Lancelets feed on suspension particles: small & blade-like chordates living in marine sands. Feeding wriggles backward into sand with head sticking out. Net of mucus secreted across pharyngeal slits trapping food particles. Water flowing through slits exit via opening in front of anus. Also have segmental muscles flexing body side to side, producing slow swimming movements. Tunicates are closest living non-vertebrate relative of vertebrates. 4 features of human embryos share with invertebrate chordates (lancelets): A dorsal hollow nerve cord: notochord, pharyngeal slits, post-anal tail. Section 20. 16 animal phylogeny & diversity revisited an animal phylogenetic tree is a work in progress.
