UT Arlington BIOL 3454 - Final Exam Study Guide (12 pages)

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Final Exam Study Guide

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Final Exam Study Guide


exam 6: Chaetognaths, echinoderms, hemichordates and Chordata

Study Guide
University of Texas at Arlington
Biol 3454 - General Zoology
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BIOL 3454 1nd Edition Final Exam Study Guide Lectures 27 30 Lecture 11 19 o 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 Hemichordata o 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 stomochord o 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 called glomerulus has an excretory function Dorsal nerve chord similar to chordates rest of NS relatively simple similar to cnidarians and echinoderms o Separate sexes One species asexual reproduction Fertilization external Larval tornaria stage in some 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 colonial Lecture 28 Lecture 11 21 I II III IV V Chaetognaths Echinoderms Hermichordates Mixed characteristics a Not all taxa are protostome or deuterostome features b Chateognaths mixed Chinoderms have a strange body plan a Bilateral ancestor and radial as adults b Coelom modified into a water vascular system for movement c Free moving but radial Phylum Chaetognatha a Arrow worms b Roots Greek chaite long flowing hair gnathos jaw c All marine d Swim to surface at night and descend during the day e Predatory f Form and function i Unsegmented ii Body plan head trunk and postanal tail iii Vestibule depression beneath the head iv Dorsally located eyes v Only invertebrates with a many layer epidermis vi Highly mobile and nearly transparent can have significant ecological impact vii Complete digestive system and well developed coelom viii U shaped ciliary loop over neck and from back of head mechanoreceptive or chemosensory ix No respiratory or excretory systems x Hermaphroditic self or reciprocal cross fertilization xi Deuterostomes but share characteristics with both groups of phyla Phylum Xenoturbellida a Hard to place taxonomy VI b Deuterostomes c Single genus with 2 species d Live in N sea mud e Feed on bivalves and bivalve eggs f Sexual reproduction with no structured gonads Phylum Echinodermata a Water vascular system of coelomic origin that doubles as part of respiratory system b Unsegemented with pentraradial symmetry c Triploblastic and coelom extensive d Endoskeleton of dermal calcareous ossicles e Digestive system usually complete axial or coiled f Bo brain but extensive nerve ring g Regeneration prominent h Asexual reproduction by fragmentation i Separate sexes free swimming bilateral larval stages j Excretory organs absent k Blood vascular system very reduced l Circulation by peritoneal cilia m Fossil record to Cambrian n Bilateral ancestor but evolved radiality slow and sessile o Most have no ability to osmoregulate p Virtually all bottom dwellers a few pelagic q Important to knowledge of evolution and development r Class Asteroidea i Starfish ii 1500 species iii Predatory iv Central discs with tapering arms v Covered with ciliatd pigemented epidermis vi Mouth that is surrounded by a soft membrane with a canal running from the mouth to the end of each arm vii Form and function 1 Aboral surface usually rough and spiny 2 Bases around spines have pincer like pedicellariae 3 Papulae soft delicate gill structures 4 Madreporite tiny pore on the aboral side leading to the water cascular system 5 Endoskeleton made of small calcareous plates called ossicles bound together with connective tissue 6 Collagen is called catch collagen and under neural control and can change from a liquid to solid state 7 Ossicles have a meshwork between them called stereom unique to echinoderms viii Water vascular system 1 Primary functions locomotion and food gathering 2 Operates hydraulically 3 Madreporite to stone canal to ring canal to several radial canals to many lateral canals to tube feet with end in an external sucker ix Digestive system 1 Mouth on oral side leads to a short esophagus to a large stomach in central disc lower part of stomach can be everted during feeding 2 Upper pyloric part of stomach is smaller and connects to pyloric ceca in each arm 3 Short intestine leads to small intestinal ceca anus inconspicuous may be absent 4 Like to eat other echinoderms and molluscs and bivalves 5 Few feed on plankton x Nervous system made of 3 units 1 Oral or ectoneural nerve ring around mouth and a redaila nerve in each arm 2 Deep or hyponeural lies aboral to ectoneural system ring around anus and radial nerves along roof of each ray 3 Epidermal nerve plexus or nerve net connects the two systems along with bodywall 4 Sense organs are not well developed 5 Ocellus at end of each arm xi Reproductive system 1 Separate sexes 2 Fertilization external eggs and sperm shed into water 3 Can regenerate lost parts 4 Many require lest part of central discs to regenerate 5 Larvae bipinarria 6 Then brachiolaria as they start to mature xii Sea daisies 1 Highly modified asteroids 2 Pentaradial but no arms 3 One species with no digestive tract just a membranous velum that absorbs nutrients s Class Ophiuroidea i Brittle stars ii 2 000 species very abundant iii Arms slender and don t really taper iv No

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