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UT Arlington BIOL 3454 - chaetognaths, echinoderms and hemichordates
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BIOL 3454 1nd Edition Lecture 27Lecture 11/21o Class Crinoidea ~ 625 species  Sea lilies, feather stars  Flower shaped body at tip of stalk rare among echinoderms in that they are rare among echinoderms in that they are attached much of their life  Some deep water most shallow water around reefs Form and function - Disc called a calyx with leathery skin called tegmen with calcareous plates- Calyx and arms together called a crown attached to a long jointed stalk in sessile forms - Oral surface with a mouth to short esophagus to long intestine with folds called diverticula to an anus which may be on a raised cone - Ambulacral grooves are open ciliated and carry food to mouth - Water vascular system functions entirely on coelomic fluid - NS has an oral ring and a radial nerve for each arm - Separate sexes - Gonads masses of cells in arms - Larvae = dolioloarium - Phylum Hemichordatao Roots Greek hemi (half)/chorda(string or chord)o Used to be a subphylum of the chordates o Have a buccal diverticulum that functions for support called stomochordo Bottom dwellers live in secreted tubed in marine sediments o Class Enteropneusta Acorn worms  Live in burrows in sand and mud Mucus covered body with 3 regions (proboscis, short collar and a long trunk) Probosicis – feeds through ciliated grooves, excavates burrows has small coelomic sac called a protocoel that leads to buccla dicerticulum  Gill pores on each side of trunk behind collar for reparation lead to U-shaped gill slits  Exchange across epithelium  Middorsal blood vessel carries colorless blood enters a network of sinuses calledglomerulus has an excretory function  Dorsal nerve chord similar to chordates rest of NS relatively simple similar to cnidarians and echinoderms These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Separate sexes  One species asexual reproduction  Fertilization external  Larval = tornaria stage in someo Class Pterobrachia  Similar to enteropneusta but some have structural differences for more sedentary lifestyle  Small live in collagenous tubes Extend crown tentacles from tubes for filter feeding retractable  One pair of gill slits Monoecious and dioecious species  Few can reproduce asexually by budding  Some


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UT Arlington BIOL 3454 - chaetognaths, echinoderms and hemichordates

Type: Lecture Note
Pages: 2
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