Laboratory 3 ? Animal Diversity III I. Directional Terms A. Anterior ? head B. Posterior ? tail C. Dorsal ? upper surface D. Ventral ? lower surface E. Lateral ? away from midline F. Medial ? toward midline G. Proximal ? nearest to point of reference H. Distal ? furthest from point of reference - if reference point not given, assume midline I. Frontal/Coronal Section ? cuts dorsal from ventral J. Cross/Transverse Section ? cuts perpendicular to midline, through main point of body K. Sagittal Section ? cuts left from right II. The Deuterostomes - blastospore becomes anus; mouth develops at secondary location - coelomate; 3 germ layers; bilateral symmetry (at least during larval stage) - complete digestive systems with mouth & anus A. Phylum Echinodermata 1. sea urchins, starfish, sand dollars 2. characterized by presence of plates that form internal skeleton a. in most, equipped with spines that project outward 3. allied to chordates by developmental similarities & similar larva form (bipinnaria larva) 4. larva are bilaterally symmetrical; adults are radially or pentaradially symmetrical 5. water vascular system, derivative of coelom, transports food, gases & waste a. circulatory & excretory systems reduced 6. Class Asteroidea a. Starfish i. star-shaped body with 5-25 arms covered by flexible spiny skeleton ii. body composed of central disc & 5 radiating arms iii. upper surface is aboral surface & lower surface is oral surface iv. aboral surface has spines, parts of small calcareous plates buried beneath outer covering & are part of endoskeleton v. small, pincer-like structures around spines keep body clean & capture food vi. small, porous, rounded structure ? sieve plate ? on aboral surface vii. tube feet lie in distinct ambulacral grooves on oral surface viii. water vascular system consists of series of seawater-filled tubes - water enters through porous sieve plate, which is connected to circular ring canal - water enters radial canals along center of each arm - internal ends of tube feet connected to ring canals - ampulla, bulb-like structure, at top of each tube foot - when ampullae contract, they force water into tube feet, causing them to extend - as each tube extends, small sucker at tip sticks to substrate, allowing starfish to pull itself along - when ampullae relax, tube feet shorten & suckers release - by alternate expansion & contraction of tube feet on different arms, starfish can move 7. Class Echinodermata a. Sea urchins i. body is globular & covered with sharp slender spines readily movable ii. spines are attached to solid, rounded shell (test) iii. spines are among pincer-like structures & tube feet iv. move around using tube feet v. in center of oral surface is oral mouth that bears 5 protrusile teeth vi. herbivorous; teeth used for grazing on sea plants vii. teeth & jaw apparatus known as ?Aristotles? lantern? b. Sand dollar i. flattened, calcareous shell covered with dense thicket of minute spores ii. aboral surface marked by characteristic 5-lobed pattern iii. sieve plate in center of aboral surface iv. on oral surface are central mouth & anus, near edge of disc v. adapted for burrowing in sand - flattened body form & reduced spines 8. Class Holothuroidea Mouth Anus Sieve Plate a. Sea cucumber i. no spines; endoskeleton reduced to series of small spicules, giving body tough, leathery quality ii. mouth surrounded by crown of tentacles, which are modified tube feet iii. body covered in tube feet, used in locomotion iv. sac-like body very muscular v. by combining contractions of different muscular layers with actions of tube feet, sea cucumber can crawl in wormlike fashion B. Phylum Hemichordata 1. acorn worms 2. soft-bodied, worm-like marine organisms often found in U-shaped burros on sandy or muddy sea bottoms 3. share characteristics with Chordata & echinoderms a. important in showing relationships of chordates to invertebrate groups 4. body divided into 3 parts a. anterior proboscis (long, flexible protruding process) b. short collar posterior to proboscis c. elongate trunk i. anterior branchial region, containing gill slits ii. genital region containing reproductive organs iii. abdominal region containing intestine 5. mouth opening on ventral surface of proboscis, at its base 6. anus located at most posterior tip of trunk C. Phylum Chordata 1. Four defining characteristics a. notochord Crown of Tentacles Tube Feet Trunk ? Branchial Region Collar Proboscis Trunk ? Genital Region Trunk ? Abdominal Region b. pharyngeal gill slits or pouches c. dorsal hollow nerve cord d. postanal tail 2. Subphylum Urochordata a. tunicates or sea squirts b. many adults are sessile & secrete a test or tunic about themselves i. composed of non-living cellulose-like material ii. secreted by thin underlying tissue (mantle) c. some are colonial, with individuals secreting common tunic d. Molgula i. tunic is thick, translucent, plastic-like outer covering ii. water enters incurrent siphon & passes into pharynx iii. water passes out of pharynx through numerous gill slits into cavity (atrium) - as water passes through slits, microscopic particles are filtered out - particles trapped in mucus & carried into intestine iv. water passes out through excurrent siphon e. Larval Tunicate i. body contains pharynx with gill openings, intestine, & sensory organs for Tunic Excurrent Siphon Incurrent Siphon Pharynx Tunic Intestine Stomach Tail Body detecting light & maintaining equilibrium ii. tail has hollow dorsal nerve cord, muscle bands, & notochord iii. tail is situated post-anally iv. 3 anterior suckers for attaching to substrate v. at end of larval life, tunicate finds suitable place to settle, fastens itself to substrate, & undergoes metamorphosis into adult form - most chordate features are lost 3. Subphylum Cephalochordata Cross Section of Pharyngeal Region Cross Section of Gut Region a. Amphioxus or Lancelet b. small, fish-like animal found in shallow marine waters in many parts of world c. streamlined body, no distinct head, conspicuous V-shaped muscles (myotomes) on body d. funnel-shaped buccal cavity at anterior end, surrounded by oral tentacles (cirri) e. pharynx has numerous gill slits & posteriorly joins intestine f. notochord extends to tip of rostrum, presumably to brace it when animal burrows into sand; may appear as row of black dots - immediately dorsal to pharynx 4. Subphylum Vertebrata a. defining features include i. cartilaginous or bony endoskeleton consisting of cranium (skull), visceral (gill) arches, & a spinal column of segmented vertebrae ii. enlarged brain which primitively has 3 divisions iii. head region with specialized sense organs Caudal fin Anus Myomeres Ventral fin Dorsal fin Dorsal fin ray Myotome Nerve cord Notochord Gills Pharynx ?Liver? Gonad Gut tube b. have postanal tail, part of trunk posterior to anus c. Agnathans i. marine lamprey represents most primitive living vertebrate - absence of jaws, true teeth, & paired appendages - poorly developed brain & skeleton - notochord persists throughout life - skeleton is cartilaginous; bone completely absent - large number of gill pouches; primitively structural arrangement of gills ii. single median nostril iii. larva lamprey referred to as ammocoetes larva; specialized features absent iv. cylindrical shape of body divided into head, trunk, & tail v. fins present only in median plane vi. buccal cavity at front of head vii. specialized ?teeth,? but no jaws, are present viii. near posterior end of trunk is shallow pit (cloaca) - excretory, genital, & intestinal products voided to surface at opening ix. saggital section - notochord ? broad, translucent rod in dorsal half - chief axial skeleton - nervous system - dorsal to notochord - small canal that contains slender spinal cord & brain - brain is enlarged, lobed structure anterior to tip of notochord - dark mass of tissue anterodorsal to brain is olfactory sac - digestive-respiratory systems - closely related anatomically Buccal funnel Head Eye Gill openings Trunk Fin Tail Buccal funnel w/ horny teeth Annular cartilegeTongue Buccal cavity Lingual cartilege Lingual muscle Myomere Spinal cord Notochord Gill pouch Heart - buccal funnel continues above tongue as narrower buccal cavity - at posterior end divides into smaller dorsal tube (esophagus) & larger ventral tube (pharynx) - 6 openings in walls of pharynx are internal gill slits, which lead into gill pouches - each pouch is lined with leaf-like structures, the gill lamellae - respires by pumping water in & out of gill pouches through openings at surface (external gill slits) - Pericardial cavity - posterior to last gill pouch; contains heart - Liver, gonad, kidney - liver is large, greenish digestive organ posterior to heart & on ventral part of body cavity; granular gonad dorsal to liver x. Cross section through eyes xi. Cross section through gill pouch xii. Cross section through heart region Myomere Pineal gland Brain Cartilage Eye Oral cavity Oral gland Lingual cavity Spinal cord Notochord Gill pouch Esophagus Dorsal aorta Lingual cartilage Pericardial cavity Heart Liver xiii. Cross section through trunk xix. Cross section through trunk, anterior to dorsal fin d. Class Chondrichthyes i. sharks, skates, rays ii. cartilaginous or elasmobranch fish characterized by cartilaginous skeleton & exposed gill slits iii. pair of pectoral fins, pair of pelvic fins, 2 median dorsal fins, & caudal fin that is heterocercal (asymmetric dorso-ventrally) iv. rough surface produced by many tiny placoid scales embedded in skin v. gnathostomes ? jawed vertebrates vi. each placoid scale consists of basal plate embedded in skin & protruding spine vii. scale composed of outer layer of enamel & inner layer of dentine viii. conical pulp cavity within each scale; same structure in vertebrate teeth - teeth & placoid scales are homologous structures ix. teeth of shark are modified placoid scales x. dorsal spiracles ? modified gill slits that will become auditory canal Gut tube Kidney Pectoral fin External gill slits Spiracle Lateral line Anterior dorsal fin Caudal fin e. Class Actinopterygii i. ray-finned bony fish ii. largest group of vertebrates in number of species & individuals iii. ctenoid scales ? bony, dermal scales with rows of spines (comb-like edge) - produced by dermal tissue & covered by epidermis which produces mucus iv. vertebral column not differentiated since all body parts move in same way v. pectoral girdle attached to back of skull (no neck) vi. caudal fin is homocercal (upper & lower halves are alike) vii. lateral line along side of body formed by row of small pores or tubules connecting with tubular canal bearing sensory organs - organs sensitive to pressure & temperature changes; detect changes in water currents f. Tetrapods i. internal skeleton provides support for body & system of jointed levers which are moved by muscles ii. terrestrial vertebrates with 4 legs iii. 3 types of vertebrate endoskeleton materials - notochord - found in every chordate at some point during life cycle - reduced in importance, progressively replaced by elements of vertebrae - persists in adults as discs found between successive vertebrae - cartilage - comprises major skeletal elements of living Agnatha & Chondrichthyes - major skeletal material in embryonic tetrapods; much later replaced by bone - bone - dominant skeletal material in most adult vertebrates - highly dynamic living tissue; constantly being reworked, by resorption of old bone & deposition of new bone - allows bone to constantly remodel itself, allowing for structural improvements to counter new mechanical stress on body - provides vast, accessible reservoir of minerals that can be withdrawn Pectoral fin Pelvic fin Lateral line Dorsal fin Adipose fin Anal fin Caudal fin as body needs them for general cellular requirements iv. skeletons contain basically same bones, some highly modified in shape v. vertebrate skeleton divided into axial skeleton (skull, vertebral column, ribs & sternum; forms body?s central axis) & appendicular skeleton (pectoral & pelvic limbs, limb girdles (scapula & pelvis; connect limbs to axial skeleton) vi. Class Amphibia - frogs & salamanders - gills present in aquatic larvae; adults have lungs - tail present in aquatic larvae; limbs develop in adult - smooth moist skin characteristic of many amphibians - require water for reproduction - frog skeleton - radioulna, fusion of radius & ulna on forearm - urostyle, represents number of fused caudal (tail) vertebrae - tibiofibula, fusion of tibia & fibula of hindlimb, adapted for jumping - curved spine - Amphibian egg - jelly layer ? permeable to water, CO2, O2, & embryonic waste products - yolk ? provisions embryo with nutrients - ?Open System? ? vulnerable to disturbance & dessication: requires moist environment vii. Class Reptilia - turtles, snakes, crocodiles - skin covered with scales derived from epidermis; may have bony dermal elements (turtles & crocodiles) - turtle skeleton - carapace, outer bony covering - Amniotic egg - shell-leathery or calcareous, protects embryo, allows CO2 & O2 exchange, prevents water loss - Chorion ? assists gas exchange across shell - Amnion ? fluid-filled sac, cushions embryo & prevents dehyrdration - Yolk ? provides embryo with nutrients - Allantosis ? stores embryonic waste products - ?Closed System? ? protected from disturbance & dessication: can be laid terrestrially - evolution of amniotic (cleiodic) e.g. permits fully terrestrial lifestyle viii. Class Aves - birds - feathers probably arose as insulation device when avian ancestors became (endothermic) warmblooded & were later adapted for flight - amniotes; calcareous shell - hollow bones; beak instead of teeth - Feathers Barb Barbules - shaft forms central axis of feather - vanes are flexible structures springing from opposite sides of shaft - barbs, individual plates, stick together - barbules are closely parallel branches designed to hook onto barbules of adjoining barbule - Skeleton - keeled sternum increases surface area & serves for attachment of flight muscles - synsacrum, a fusion of sacral vertebrae & pelvic girdle, add strength to vertebral column - caudal/tail vertebrae are fused to form pygostyle - radius ? the longer of the two, is on lateral side of ulna ix. Class Mammalia - covered with hair in varying degrees; warmblooded - mammary glands in females produce milk to nourish young - young are born alive; monotremes lay eggs, like reptiles - marsupials (opossums, kangaroos, koalas) give birth to immature live young nursed in special pouch (marsupium) - placentals retain young in uterus until they are relatively well developed Shaft Vanes Christopher Laboratory 3 ? Animal Diversity III
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