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ZOO2090 Final: Zoo Lab Final Notes

Course Code
ZOO 2090
Jinzhong Fu
Study Guide

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Zoo Lab Final Notes
Identifying characteristics of classes
Chordate vs. vertebrate
oChordate: notochord, pharynx with slits, endostyle/thyroid, posterior tail,
hollow nerve chord
oVertebrate: more de!ned organs/internal structures, head
Presence of/traces of vertebrae
Enlargement of nerve chord forming brain, protected by cranium
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
oIndicate 4cm long, V-shaped myomeres, large eyes, possible notochord
Chordate features – non vertebrate chordates
oUrochordata (sea squirts)
Endostyle – produces mucus, traps food particle
Possibly homologous to subpharyngeal gland
Hermaphroditic or asexual budding
Simple heart, alternating direction of 1ow
Gas exchange across tissues of pharyngeal bars
No discrete organs for excretion – wastes empty to atrium and leave
through excurrent siphon
oCephalochordata (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 1ows through pharynx – bars trap food, water
through slits
Water exits body through atriopore
Endostyle located in 1oor 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

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Comparing jawless, cartilaginous and bony !sh
External features and body shape and lifestyle
oLamprey – distinct notochord
Cartilaginous skeleton
Distinct brain, heart, liver (with gall bladder) and kidney
Velum – muscular 1aps
Pharynx opens directly to environment (rather than atrium)
Seven external gill slits – pouches lined with lammellae
Slimy, scaleless, tubular → laterally compressed
2 medial dorsal !ns, symmetrical caudal !n, jawless oral disc with oral
Paired lateral eyes, single dorsal pineal eye, posterior = single nostril
Ventral surface – urogenital papilla from cloaca
oShark – Squalus
Gills open to pharynx, nares open to olfactory sac – no connection to
Fins paired laterally, singular dorso-ventrally
Cloaca between pelvic !ns – males have claspers
Homocercal tail
oPerch –teleost
Di>erences in tail shape, head shape (1attened laterally), some paired
dorsoventral !ns, no !ns covering cloaca, fewer gill slits
Basic structure of integument – compare the 3 groups
oEpidermis (from ectoderm)
odermis (from mesoderm) – connective tissues (collagen !bres), smooth
muscle, nerves, blood vessels
oChromatophores – pigment cells
Melanophores – black, brown or reddish colour from melanin
Xanthophores – yellow
Eryhtrophores – red
Iridophores – scatter/re1ect light
oLamprey – epidermis contains dark epithelial cells and paler unicellular
Beneath is connective tissue of dermis (orange)
Scattered brown chromatophores
Beneath this is muscle
Mucous cuticle on top of epidermis
oShark – placoid scales (small hooked structures) – unique to chondrichthyes
Note direction - for 1uid dynamics
Dermis divided into stratum spongiosum above stratum compactum
oOsteichthyes – dermally derived scales in dermis projecting towards surface
Covered by thin layer of epidermis
Various chromatophores in dermal layer near junction with epidermis
Di>erent types of scales
oGanoid Scales (gars and bichirs) – rhomboidal and opaque
Enamel-like coating on acellular bony case

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oElasmoid Scales – lack enamel layer from ganoid scales (layers of lamellar
Most bony !shes (perch has ctenoid)
Cycloid – thin, transparent, smooth distal edge
Ctenoid – cone-like projections on exposed margin
Major skeletal components – compare 3 groups
oFunctions: muscle attachment and hinged body segments, protect internal
oDivided into cranial (head) and post cranial (body – trunk and appendicular)
Made of bone and/or cartilage
oLamprey – 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
oShark – 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 !n has three large basal pterygiophores which connect to
coracoid bar
Distal = radial ptergiophores attached to !n rays called
Pelvic girdle from ischiobpubic bar with lateral projections
Radial pterygiophores also present
Some sexual dimorphism - claspers in males
Ceratotrichia support !ns distal to cartilage
Braincase = only chondrocranium – completely surrounds brain case
Remains cartilaginous throughout life span
Rostrum !lled with gelatinous material
Supraorbital crest dorsal to orbit perforated by small holes
oSuper!cial ophthalmic foramina
Inner ear within cartilage of otic capsule
Foramen magnum – where spinal cord enters skull
Splanchnocranium – supports gills
Seven arches – !rst arch modi!ed 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)
oCan lower upper jaw
Second visceral arch involved in jaw suspension
oPerch – super!cially resembles that of shark
Skull has very di>erent shape
Most bones belong to dermatocranium (bones formed in dermis)
Gill support di>erent
Pectoral girdle fused
Vertebrae extended
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