Phylum Chordata (Part 1: Lower Chordates) Bio 1413: General Zoology Lab Ziser, 2008 [Exercise 17, p265 & Exercise 18, p 275] Identifying Characteristics of the Phylum -dorsal, hollow, tubular nerve cord -notochord for support -paired gill (pharyngeal) slits -segmentation in some systems -most with postanal tail -deuterostome development Body Organization and Charactristic Structures -cartilaginous notochord for support in larva, adult or both -pharynx used for filter feeding and/or respiration Classification: Subphylum: Urochordata (Tunicates) - solitary or colonial; microscopic to 1 ft in diameter -motile larvae with dorsal nerve cord and notochord -adults sessile and lacking these characteristics -no cranium or braincase Subphylum: Cephalochordata (Lancelets) -burrow in sand; active swimmers -elongated, streamlined,fishlike vertebrates with all chordate characteristics in adult stage Subphylum: Vertebrata (vertebrates) -all chordate characteristics in either the embryonic or adult form -well developed cephalization -endoskeleton with cranium enclosing the brain and vertebrae enclosing the spinal cord Lab Activities: Subphylum: Urochordata 1. The Adult Tunicate (p 266): Slides: Ecteinascidia wm, Ecteinascidia is a sessil benthic sea squirt; Salpa, Doliolum, Salpa, Doliolum, and Oikopleura are planktonic Oikopleura look at each slide and try to find the following: tunic, incurrent and excurrent siphons, gill slits, pharynx, gill slits, digestive tract, anus, muscle bands 2. Ascidian Larvae (p 269): Slides: Ascidian tadpole & know: adhesive papillae, branchial basket, intestine, ascidian swimming tadpole atriopore, notochord Subphylum Cephalochordata 3. Amphioxus (p270): Slide: Amphioxus immature, wm know: rostrum, oral cirri, notochord, fin rays, myomeres, dorsal nerve cord, pharynx, gill slits, hepatic caecum, intestine, anus 4. Amphioxus cross sections (p 273): Slide: Amphioxus representative cs cross section through pharyngeal region: skin, epidermis, dermis, dorsal fin, fin ray, myomeres, dorsal nerve cord, notochord, pharynx, gill slits, gill bars, atrium, gonads, metapleural fold, ventral aorta cross section through intestinal region: dorsal fin, fin ray, dorsal nerve cord, notochord, myomere, dorsal aorta, intestine, ventral fin Subphylum Vertebrata 5. The Adult Lamprey (Ex 18, p 278): Preserved Specimens, external anatomy; know: dorsal fin, caudal fin, rasping plastimount teeth, eyes, median nostril, gill slits, lateral line, anus observe the prepared sagittal sections to find the internal anatomy; know: notochord, brain, spinal cord, myotomes, digestive tract, oral hood, mouth, tongue, esophagus, intestine with typhlosole, pharynx, liver, gonad, kidneys, heart 6. Lamprey Larva, Ammocetes (Ex 18, p 275): Slide: Ammocetes, wm know: oral tentacles, eye, caudal fin, myotomes, gill pouch, notochord, brain, spinal cord, intestine, cloaca Demonstrations: • Similarities between the larvae of Hemichordates and Primitive Chordates • Deuterostome Evolution & Generalized Chordate • Vertebrate Relationships • Representative Urochordates (tunicates) • Metamorphosis in Tunicates • Representative Cephalochordates • Phylum Chordata; Class Agnatha Notebook Suggestions: How do sessile and planktonic tunicates differ from each other How does the anatomy differ between larval and adult tunicates Compare tunicate larvae with lamprey larvae; what are the similarities, what are the differences Disposal: Do not discard, return preserved animals to bucket.