Lab 8: Echinoderms and Chordates

Task 1: Phylum Echinodermata coelomate; unsegmented pentamerous radial symmetry water vascular system dermal endoskeleton with spines

Task 1: Phylum Echinodermata 4 selected classes to discuss: Asteroidea (sea stars or starfish) Ophiuroidea (brittle stars) Echinoidea (sea urchins and sand dollars) Holothuroidea (sea cucumbers)

Task 1: Phylum Echinodermata or each: compare to Fig. 8-1, note body plan 5-part radial symmetry, endoskeleton, lack of segmentation Asteroidea (sea stars) – five arms, madreporite, central disc, mouth, tube feet, coelom Ophiuroidea (brittle stars) – five arms, central disc Echinoidea (sea urchins and sand dollars) – look for pentamerous characteristics; jaws more…..

Task 1: Phylum Echinodermata examine the preserved specimens, note the following: Holothuroidea (sea cucumbers) – not typically sedentary, just slow (lab manual is wrong) tentacles at mouth; cloaca and vent at anus radial muscles alimentary canal (intestines) - thick gonad – thinner, orange respiratory trees – very thin, highly branched

Tasks 3 and 4: Chordates group unified by four traits present at some point in the life cycle for all members dorsal tubular (hollow) nerve cord notochord pharyngeal gill slits postanal tail

Tasks 3 and 4: Chordates three subphyla Urochordata – tunicate or sea squirt Cephalochordata – lancelet or amphioxus Vertebrata – have a backbone; fish, amphibians, reptiles, birds, and mammals (classes listed later) watch the video for some information on the body plan and development….

Task 4: Vertebrate Chordates Vertebrata – 7 classes Agnatha – jawless fish Chondrichthyes – cartilaginous fish (sharks, skates, and rays) Osteichthyes – bony fish with paired fins Amphibia – two pairs of legs; smooth skin (frogs, salamanders, etc.) Reptilia – two pairs of legs; scaly skin (lizards, snakes, alligators, etc.) Aves – feathers; paired wings and legs (birds) Mammalia – hair, mammary glands, two paired appendages

Task 3: Invertebrate Chordates examine the preserved specimens and models, note the following: Urochordata – tunicate or sea squirt sessile adult; cellulose tunic, holdfast, siphons, pharynx image on following slide….

Task 3: Invertebrate Chordates examine the preserved specimens and models, note the following: Cephalochordata – lancelet or Amphioxus specimen, model, and slide; match to Figs. 8-2 and 8-3 note oral hood, fins, myotomes, dorsal nerve cord, notochord, pharynx, pharyngeal gill slits, postanal tail; other items from figures

Task 4: Vertebrate Chordates obtain a “vertebrate box” and examine the preserved specimens, note the following: Agnatha – brook lamprey jawless; single median dorsal and caudal fins (no paired lateral fins); 7 pairs of external gill slits Chondrichthyes – shark scales (makes sandpapery skin); various fins (note especially those in pairs); claspers on pelvic fins of mature males; cloacal opening

Task 4: Vertebrate Chordates obtain a “vertebrate box” and examine the preserved specimens, note the following: Osteichthyes – yellow perch scales, operculum over gills, various fins (note pairs); lateral lines (from operculum to caudal fin) Amphibia – leopard frog and salamander smooth skin (no scales); 4 legs – count digits; tympanum on frog; eyelids (do other box items have eyelids?)

Task 4: Vertebrate Chordates obtain a “vertebrate box” and examine the preserved specimens, note the following: Reptilia – green anole lizard, turtle, and garter snake scaly skin, 4 legs (reduced to vestigial in snake); lizard – claws, eyelids; turtle – carapace and plastron Aves and Mammalia – no specimens demonstration table – identify specimens by class