BISC 316 MT 1 notes.docx

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Simon Fraser University
Biological Sciences
BISC 316
Tammy Mc Mullan

Chordata Paedomorphosis -Pharyngeal slits -sexually mature with larval characteristics -Notochord -larval form acquired number of changes -Dorsal hollow nerve chord -elongation -post anal tail -slits in pharynx -segmented muscles Vertebrata -bone -Pharyngeal slits -notochord Evidence -Single dorsal hollow nerve cord -pelagic larvae -post anal tail -one way gut -bilaterally symmetrical -bilaterally symmetrical -cephalization EXAMPLE mount seymore brown salamander -coelom -spends a year in water in larval stage -closed circulatory system -higher elevation, never becomes terrestrial -most have endoskeleton -appendages Classification -genital and excretory system KPCOFGS Kids play catch on farmer greens shed Cephalochordata Kingdom,Phylum,Class,Order,Family,Genus,Spe -Amphioxus cies -no paired fins -notochord – no cranium Overview of 9 classes of vertebrates -major blood vessels -digestive tract Agnatha – jawless fish -pharyngeal slits -Head with cranium, brain, paired eyes -Vertebrate – cartilaginous elements on dorsal Urochordata surface of notochord -a large pharynx -bones present as scales, armor in some -inhalent, exhalent siphons -mouth, but no jaws, no true teeth -most sessile -no pectoral or pelvic girdle -have pectoral spikes or folds Larvae form urochordata -no appendages -larval form tadpole like -gills in pouches -pharyngeal slits -Living agnathans (lamprey, hagfish) -muscular post anal tail -Larval form of lamprey very similar to ancestral -dorsal hollow nerve cord body plan of vertebrates -notochord -free swimming Placodermii (=plate skin) Paleoclimates -Extinct group of fishes -major influence on evolutionary success of an -covered with bony armor organism -anterior of body(head) -well adapted will survive -head joint to body by hinge in armor (can tilt -late Cambrian, major extinction of marine head up) inverts -persistant notochord -carboniferous first “amphibian” non amniotic Novel features tetrapods -Jaws enlargement and adaptation of a visceral -Mid carboniferious – first amniote, first no arch larger, harder food amniotic egg sac reptile to have amniotic eggs -paired appendages -Late carboniferous – amniotes splits into -gas bladder ancestors of mammals and birds/reptiles -Late Permian mass extinctions 95% of all Chondrichthyes marine species -skates, rays, sharks, chimaera (ratfish) -very little or no bone CLASS AGNATHA -modern species cartilaginous -earliest vertebrates -small toothlike scales called denticles -paraphyletic assemblages of jawless fish Made of dentine and enalmel “ostracoderms” -multiple external gill slit openings Three major groups -no gas bladder, use liver for bouncy -cambrian agnatha -paired nostrils blind olfactory sacs -ostracoderms -teeth anchored to skin at margin of jaws -cyclostomata Acanthodii “stout” spines Cambrian agnathans -numerous paired fins Vertebrate characteristics Thin membrane supported stout spines -cranium -all extinct -w shaped myomeres -streamlined bodys, large eyes, wide mouth -notochord with vertebral element “cartiledge” with many teeth, bony head, small hard scales -sense organs clustered in head region  active swimmers and predators -branchial arcdhes appear more derived than hagfish Osteichthyes -no bone or mineralized scales -evolved from an ancestor common with acanthodian 400 mya -last 250 mya dominant fish most abundant vertebrates on earth -bone – skull, vertebrae, girdle, fin, scales -have some cartiledge -gills in bony operculum -either have a lung or gas bladder for bouncy Ostracodermata -1-15 gill opening – no relationship with gills -pharaphyletic assembelage and gill openings -all had coverings of dermal bone -kidney – primitive vertebrae system -cerebellum present (not present in -accessory hearts, blood sinuses, low blood hagfish/lamprey) pressure -no jaw (some had moveable mouth plate) -very few immune reactions -midlien dorsal fin -msucle pharyngeal pump Lamprey -gillls -andromous, lay eggs upstream live in large -2 semicircular canals body of water Divide into 2 groups -parasitic -larvae filter feeders A. pteraspida Characteristics -headshield of fused body plates -small vertebral elements -lateral and dorsal spines on shield -7 gill pouches, tidal respiration -not fins but part of the armor -primitive vertebrate nervous system -spines stopped “rolling” -Chloride cell in gill and kidney for regulation -post cranial exoskeleton and nnitrogenous waste -no paired appendages/dorsal/anal fins -hypocercal tail Lamprey larvae (ammocoetes) and amphioxus Evolutionary trends -larval form increased efficiency in locomotion Similarities increased feeding efficiency -notochord -dorsal hollow nerve chord Cephalaspida -segmented muscles -body shapes a lot diff body shape means basic -straight instetines biology is different -pharyngeal gill slits -heavily armored headshield and smaller plates -postanal tail on body Differences -headshield all same size, speculate shield -eyespot present in amphioxus develops when fully grown -brain more complex in ammocoetes -fusiform or flattened body -7 vs 50 gillslits -most have hypocercal tail -pharynx has muscles and cartilaginous skeleton -live on bottom of ocean -stabilizing projections or folds Hard mineralized tissue are ancestral vertebrate structures Xinoidea (hagfish) Advantages -lack vertebrae -calcium and phosphorous reserves -scaleless -efficient movement -2 horny plates border sides on tongue like -protection structure -buffers for blood pincer like action -increase body weight, keep you where food is Skeletal support elements -notochord Bone -cartiledge - always found deep in dermis -bone -25-30% organic matter -cells alive in matrix Notochord -sheet of fluid filled cells Dentine -first structural support tissue -mesoderm-ectoderm boundary by mesodermal -present in all vertebrae cells -internal to enamel and external to bone Cartiledge -teeth, denticles, scales, external armor -less salt than bone -inorganic salts of hydroxypatite -cells lack connection between cells -25% organic matter -deep lying tissue, below skin -harder than bone -embryos and young vertebrates -cells do not stay in matrix -cyclostomata, chondritcheyes, few osteichthyes Enamel -hardest tissue in vertebrate body Bone -produced by ectoderm on top of dentine Types of bone -teeth, superficial denticles, scales, armor plates -found in outer layer Dermal Bone -3% organic matter -forms directly over mesenchyme, no -no internal cells – dead tissue cartilaginous precursors -thin plates of collagen matrix, salts deposited Dermal scales and derivitives -plates expand outer margin and thicken by -ostracoderm armor adding new layers on inner and outer surface -cosmoid scales -bones of the skull, pectoral girdle 4 layers -lamellar bone Replacement bone -vascular or spongy bone -Bones can replace cartildge = replacement or -dentine endochondral bone -enamal -osteoblast enters along the blood vessel -strucutre is similar to bony elements in living -typical of vertebrate long bones vertebrates -bone can also be added to the margins and other surfaces Mineralized tissue -Three types -bone -dentine -enamel Evolution of bone Acanthodii -degradation and loss of superficial layers -well developed cranium and vertebral column ganoid scales -large notochord elasmoid scales, bone than thin glaze of -dorsal and anal fins numerous paired fins enamel -probably used for good locomotion -fins had a stout spine with tissue flap Progressive loss of deep layers -fast swimming aggressive predators -denticles -shark like teeth -teeth -first group we talk about that has true teeth -teeth lack enamel, just have dentine On hard structures that have evolved from bony scales Placoderm and acanthodian versus -osteodermsi n under the horny scutes of ostracoderm crocodilians and other reptiles -jaws -membrane bones -paired fins -fin rays of bony fish -internal support (girdle) -vertebrae SUPERCLASS GNATHOSTOMES (jawed fish) -spiracle valve in small intestine 4 clades of gnathostomes present -renal portal system -placoderm -oviducts and mesonephric ducts -acanthodii -more complex reproduction system -chondricthyes -pancreas with endocrine and exocrine function -osteithyes -evolution of spleen Placoderms (plate skin) Vertebrate skeleton -all extinct -Visceral skeleton = splandocranium -benthic , bodies dorsal – ventrally flattened -gill arch, jaw, hyoid arch -jaws but no true teeth, no dentine/enamel ancestral condition supports gill -paired appendages with girdle mesenchyme cells derived from neutral crest -vertebrae with neural and hemal arches -gas bladder Gill arch -heavy armor -each gill arch consists of a series of -gap in bony plates allowed head articulation cartilanginous or bony elements -class placoderm diverges early Somatic skeleton = vertebrae, ribs Dermal skeleton = dermal bones, some bones around girdle, bones around cranium Jaws -stronger bite, capability for cutting and -Jaws  teeth grinding -teeth  grasping objects, biting, grindings, -allows organism to bite stronger harder manipulation of objects, defence organisms new resources available -lungfish, all tetrapods, placodermi, holocephali (ratfish) Evolution of jaws -first gill arch is lost – incorporated into the Advantages of Jaws base of the cranium -manipulation of objects -second gill arch becomes mandibular arch -grasp objects more firmly (upper and lower jaw) -teeth -greater support for the jaws -defence -jaws attatched to cranium -new food items and habitats -hyomandibular Lecture 7 Jaw suspension Acanthodii and Placodermii -changed and enhanced by different types of -three major adaptations jaw suspension 1.jaws 2.paired fins 3 types 3.vertebrate -amphistylic -hyostylic Paired fins -autostylic -improved mobility and steering -advantages of paired fins Amphistylic -increased control of movement -palatoquadrate attatched by ligaments to -evading predators, catching prey cranium and the hyomandibular -increased S.A greatly improves maneuverability -palatoquadrate is not fused to cranium –provide lift and allows descent -fossil sharks, some living sharks, crossopterygii, -convert forward thrust to other directions acanthodii -defense – some bony fish have poisonous spines on paired fins Hyostylic -visual communication – fighting fish -hyomandibular attatched to jaw and cranium by ligaments Origins of paired fins -derived condition in most living sharks and ray -agnathans had spines or enlarged scales finned fishes -ostracoderm “fins” derived from dermal armor -allow for grasping of prey ; solidly attatched to body -paired fins present in acanthodii and Autostylic placoderms -palatoquadrate firmly associated with or fused -acanthodii – 2 rows of
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