Lab13_Chordata

Lab13_Chordata - Phylum Chordates Defined by the presence...

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1 Phylum Chordates • Defined by the presence of four morphological features : (1) pharyngeal gill slits, (2) a notochord, (3) a dorsal hollow nerve cord, and (4) a muscular tail that extends past the anus. • Hemichordates are not members of phylum Chordata because they have only pharyngeal gill slits that function in feeding and gas exchange. (dorsal hollow nerve cord) (pharyngeal gill slits) Phylum Chordates • Include 42,500 species of fish, amphibians, reptiles, and mammals. • Bony skeleton provides sites for muscle attachment for efficient movement. • Three subphylum – Urochordata (tunicates) suspension feeders that live attached to hard substrates in the ocean. – Cephalochordata (lancelets) look like fish –Vertebrata
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2 Subphylum Urochordata • Tunicates (or sea squirts) • Larvae posses the general chordate form, lost them in adult. • Water is filtered for food and food is collected by mucus on the pharyngeal basket and moved to stomach and intestine. Mouth (incurrent siphon) Atriopore (excurrent siphon) Stomach Tunic Subphylum Cephalochordata • Commonly called amphioxus (common genus Branchiostoma ) • Buccal cavity surrounding mouth pharynx with gill slits (gill arches) anus postanal tail • Water enters mouth and exits through slits moves into atrium leaves body through atriopore . Anus Buccal cavity with tentacles Intestine Atriopore Atrium • Lancelets are small, fishlike, marine chordates that burrow in sand or mud.
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3 Subphylum Vertebrata • Fish, birds, amphibians, reptiles, and mammals. • Have a
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This note was uploaded on 02/25/2011 for the course BIO 138 taught by Professor Wu during the Summer '08 term at Staten Island.

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Lab13_Chordata - Phylum Chordates Defined by the presence...

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