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Zoo Lab Final Notes.docx

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ZOO 2090
Fred Laberge

Zoo Lab Final Notes LAB 1 Objectives:  Identifying characteristics of classes  Phylogenies  Chordate vs. vertebrate o Chordate: notochord, pharynx with slits, endostyle/thyroid, posterior tail, hollow nerve chord o Vertebrate: more defined organs/internal structures, head  Presence of/traces of vertebrae  Enlargement of nerve chord forming brain, protected by cranium (skeletal)  Distinct heart, kidneys and liver with gall bladder  Conodont fossil material o “teeth” like shapes – distinguish from rocks  Smooth texture, presence of straight lines/indentations o Indicate 4cm long, V-shaped myomeres, large eyes, possible notochord  Chordate features – non vertebrate chordates o Urochordata (sea squirts)  Endostyle – produces mucus, traps food particle  Possibly homologous to subpharyngeal gland  Hermaphroditic or asexual budding  Simple heart, alternating direction of flow  Gas exchange across tissues of pharyngeal bars  No discrete organs for excretion – wastes empty to atrium and leave through excurrent siphon o Cephalochordata (lancelets – branchiostoma)  V-shaped myomeres (muscle segments)  Separated by myosepta  Can view gonads – segmentally arranged  Can determine sex through cross section of gonads  Identify: notochord, hollow nerve cord  Wheel organ – bands of cilia line oral hood  Food passed through buccal cirri  Through opening in membrane called velum  Surrounded by velar tentacles  Water/food flows through pharynx – bars trap food, water through slits  Water exits body through atriopore  Endostyle located in floor of pharynx  Midgut caecum/diverticulum – liver like function  Darkly stained ileocolic ring – food is mixed before intestine  Respiration primarily over entire surface of organism  Nephridia (segmentally arranged) remove nitrogenous wastes  External fertilization Lab 2 Objectives:  Comparing jawless, cartilaginous and bony fish  External features and body shape and lifestyle o Lamprey – distinct notochord  Cartilaginous skeleton  Distinct brain, heart, liver (with gall bladder) and kidney  Velum – muscular flaps  Pharynx opens directly to environment (rather than atrium)  Seven external gill slits – pouches lined with lammellae  Slimy, scaleless, tubular → laterally compressed  2 medial dorsal fins, symmetrical caudal fin, jawless oral disc with oral papillae  Paired lateral eyes, single dorsal pineal eye, posterior = single nostril  Ventral surface – urogenital papilla from cloaca o Shark – Squalus  Gills open to pharynx, nares open to olfactory sac – no connection to respiration  Fins paired laterally, singular dorso-ventrally  Cloaca between pelvic fins – males have claspers  Homocercal tail o Perch –teleost  Differences in tail shape, head shape (flattened laterally), some paired dorsoventral fins, no fins covering cloaca, fewer gill slits  Basic structure of integument – compare the 3 groups o Epidermis (from ectoderm) o dermis (from mesoderm) – connective tissues (collagen fibres), smooth muscle, nerves, blood vessels o Chromatophores – pigment cells  Melanophores – black, brown or reddish colour from melanin  Xanthophores – yellow  Eryhtrophores – red  Iridophores – scatter/reflect light o Lamprey – epidermis contains dark epithelial cells and paler unicellular glands  Beneath is connective tissue of dermis (orange)  Scattered brown chromatophores  Beneath this is muscle  Mucous cuticle on top of epidermis o Shark – placoid scales (small hooked structures) – unique to chondrichthyes  Note direction - for fluid dynamics  Dermis divided into stratum spongiosum above stratum compactum o Osteichthyes – dermally derived scales in dermis projecting towards surface  Covered by thin layer of epidermis  Various chromatophores in dermal layer near junction with epidermis  Different types of scales o Ganoid Scales (gars and bichirs) – rhomboidal and opaque  Enamel-like coating on acellular bony case o Elasmoid Scales – lack enamel layer from ganoid scales (layers of lamellar bone)  Most bony fishes (perch has ctenoid)  Cycloid – thin, transparent, smooth distal edge  Ctenoid – cone-like projections on exposed margin  Major skeletal components – compare 3 groups o Functions: muscle attachment and hinged body segments, protect internal structures o Divided into cranial (head) and post cranial (body – trunk and appendicular)  Made of bone and/or cartilage o Lamprey – cartilage (pink/purple)  Some arcualia (plates) beginning to surround notochord  Most of skeleton is branchial basket – supports gills  Some cartilage support head region – some preotection for brain o Shark – vertebral column relatively unspecialized (uniform forces)  Vertebral column protects nerve chord, used for lateral undulation  Consists of only trunk and caudal vertebrae  Pectoral girdle – coracoid bar continuous with scapular processes  Base of fin has three large basal pterygiophores which connect to coracoid bar  Distal = radial ptergiophores attached to fin rays called ceratotrichia  Pelvic girdle from ischiobpubic bar with lateral projections  Radial pterygiophores also present  Some sexual dimorphism - claspers in males  Ceratotrichia support fins distal to cartilage  Braincase = only chondrocranium – completely surrounds brain case  Remains cartilaginous throughout life span  Rostrum filled with gelatinous material  Supraorbital crest dorsal to orbit perforated by small holes o Superficial ophthalmic foramina  Inner ear within cartilage of otic capsule  Foramen magnum – where spinal cord enters skull  Splanchnocranium – supports gills  Seven arches – first arch modified to form jaws (homodont teeth)  Mandibular arch of upper jaw (palatopterygoquadrate bar) and lower jaw (meckel’s cartilage)  Upper jaw not fused to brain case – connection through hyomandibular cartilage (hyostylic) o Can lower upper jaw  Second visceral arch involved in jaw suspension o Perch – superficially resembles that of shark  Skull has very different shape  Most bones belong to dermatocranium (bones formed in dermis)  Gill support different  Pectoral girdle fused  Vertebrae extended  Bony skeleton  V – shaped muscles Lab 3 Objectives:  Components of digestive system – compare 3 groups o Lamprey  Prominent feature = rasp (at end of cartilage supported tongue)  Pharynx divides into dorsal esophagus and ventral respiratory tube  Blood goes directly from esophagus to intestine (no stomach)  Wastes leave body through anus in cloaca  Large liver at posterior end (green/orange) o Shark  Food enters pharynx through mouth  Enters short esophagus (small projections) to J-shaped stomach (longitudinal folds – rugae)  Phyloric sphincter at end of stomach – controls passage of food to intenstine  Duodenum – receives bile, digestive enzymes  Liver extremely large- two large lobes and smaller medial lobe  Large due to bioaccumulation/magnification of toxins  Pancreas has two pale, thin connected lobes (ventral of duodenum and caudal and dorsal to stomach)  Ileum contains spiral valve – increases absorptive surface  Colon → rectum →anus  Rectal gland – finger like projection that enters digestive tract at colon/rectum  Involved in salt secretion o Perch – have swim bladder – thin-walled air sac along dorsal surface  Respiratory system – compare 3 groups o All have large surface area, thin barrier, large diffusion gradient, highly vascularized membrane o Lamprey - pouched  Velum closes off respiratory tube while eating  Gill slits lead from respiratory tube to gill pouches wh2re O exchange occurs  Exchange across gill lamellae, water leaves through external gill slits  No connection to nostril, during feeding breathes through tidal ventilation o Shark - septal  5 pairs of internal gill slits with rakers and lamellae  Gills one either side of interbranchial septa (holobranch)  first gill slit = hemibranch  Each primary lamellae has many secondary lamellae – site of gas exchange  Spiracle – remnant of first gill slit  Water enters pharynx through mouth and spiracles, flows over gill sand out slits o Perch – Opercular  nobby gill rakers – prevent debris flowing across filaments  4 branchial arches, all hemibranch  Water flows into mouth and out opercular cavity  Single circuit circulatory system o Blood-vascular system (blood, heart, aortic arches, systemic arteries, veins) o Lymphatic system – fat laden interstitial fluids (includes lacteals in gut) o Portal veins – back to heart via another organ o Lamprey  Heart anterior to liver  3 parts: Medial sinus venosus, Sac-like atrium, Muscular ventrical o Shark  Spleen – large triangular structure posterior to stomach (manufactures blood cells)  Heart – large muscular ventral lobe = ventrical  Receives blood from bilobed, single chambered atrium  Atrium receives blood from sinus venosus (triangular structure)  Regions assume S shape (unlike straight line in teleosts)  Oxygenated blood collected by collector loops o Pre and posttrematic branches (cranial and caudal) o Perch – blood flow heart → gills → capillary bed  Aortic arches o Arteries which leave ventral aorta – take blood to kills  Branche into two afferent branchial arteries o Continue dorsally from gills to converge at dorsal aorta o Primitive had 6 pairs – since modified  Isometric vs. allometric growth o Isometric – all at same rate o Allometric – disproportionate Lab 4 Objectives:  Methods of eliminating wastes o Kidneys = extract excess water, salts and nitrogenous wastes o Gills – void excess ammonia, urea, carbon dioxide and water o Integument passes water, oxygen, carbon dioxide and salts o Salt glands (ex. rectal gland) rid excess sodium and chloride ions o In most fish, kidneys control water/salt balance, gills control nitrogen excretion  Components of urogenital system (kidneys and ducts) – compare 3 groups o Kidneys develop from paired ridge of tissue (nephric ridge) that runs along dorsal surface of body cavity  From anterior ridge = pronephric kidneys (only in embryos)  From middle/caudal portion = oposthonephric kidneys (adult anamniotes) o Ducts drain urine from kidneys (all homologous) – archinephric ducts  Sometimes named for kidney they drain  Also carry sperm to cloaca (sole purpose in organisms with metanephric kidneys - have ureters for urine) o Lamprey  Opisthonephric kidneys lateral to gonad  Duct lies within free edge of each kidney o Shark  Opisthonephric kidneys – seen through dorsal lining, most of trunk length  Easily seen in males  Follow to urogenital sinus (holds sperm or urine)  Exit body through urogenital papilla in cloaca  Accessory urinary ducts in large males – carry all urine from kidneys o Not present in female– urine travels down opisthonephric duct  Pathway of gametes from gonad to fertilization o Lamprey  Gonads fused midline  Ovary has granular appearance, testis is smoother  No genital ducts – gametes released directly into coelom  Released through urogenital papilla o Shark  Testes on dorsal surface near esophagus, supported by mesentry (mesorchium)  Sperm travel down efferent ductules to kidenys  Pass through modified kidney tubules into opisthonephric duct  Near cloaca, duct widens into seminal vesical  Mature males have small sac protruding from caudal end of seminal vesicle  Sperm run down groove on surface of clasper  Facilitated by forceful expulsion of seawater from siphon (muscular sac under skin on pelvic fin)  Ovaries near esophagus (may contain large eggs)  Fully developed eggs break through follicle walls and enter coelom  Move towards ostium (opening in oviduct)  Egg can travel down either oviduct to nidemental or shell gland (sperm storage)  Thin membranous covering over several ova  Egg package = candle – continues into ovisac  Reabsorbed, retained for 22 months before passing out of body through cloaca o Perch – difficult to see  Differences and implications of internal vs. external fertilization  Structure of brain – differences in 3 groups o Divided into 3 regions  Prosencephalon (forebrain), mesanscephalon (midbrain), rhombencephalon (hindbrain) o Lamprey – very simple brain o Shark  Most anterior = paired olfactory bulbs – connected to olfactory sacs  Olfactory tracts – nerve fibres terminate at olfactory lobes  Cerebrum – integrates sensory information, initiates motor impulses and memory storage  All together = telencephalon  Large optic lobes receive info from eyes  Cerebellum – controls body equilibrium, coordinates fine motor activity  Large oval body  Lateral to cerebellum = auricles (flap like)  Receive info from inner ear and lateral line system  Mylencephalon – most anterior part of brain  Has medulla oblongata – regulates reflexes (ex. breathing)  Continuous with spinal cord  Has interconnected hollow spaces (ventricles) filled with cerebrospinal fluid  Cushions brain and spinal chord  Basic arrangement of cranial and spinal nerves o Nervous system changes very little across vertebrate classes  Composed of central and peripheral nervous system  Sensory (afferent) and motor (efferent) nerves  Somatic (skin and voluntary) and visceral (involuntary) o Originally 10 pairs, lateral line provide additional six pairs of cranial nerves  Also nervus terminalis left out (total 17) o Olfactory, optic, oculomotor, trochlear, orbital, abducens, facial/hymandibular, statoacoustic, glossopharyngeal, vagus  Structure and function of various sense organs o Mechano, chemo and photoreceptors – convert stimuli to impulses o Nose – chemosensory cells at base of olfactory lamellae  Water enters through each half of semi-divided naris  Flows through olfactory lamellae  Exits through other half of same naris o Eye – set in orbit, bordered by immovable eyelids  Movement controlled by 6 extrinsic eye muscles  Eyeball consists of fibrous outer tunic (opaque at back, transparent at front)  Front also covered by vascular conjunctiva  Spherical lens suspended behind iris by ciliary body, suspensory ligaments and vitreous humor between lens and retina  Aqueous humor in front of lens  Amount of light hitting retina controlled by iris adjusting pupil size o Ear  Inner ear housed in otic c
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