BIO 102: First Lab ExamChapter 1: General Considerations on Animal FormA. Descriptive Terms:

Dorsal back / upper side (posterior in humans)Ventral under side (anterior in humans)Lateral side [L & R]Anterior/Cephalic/Cranial head-end (superior in humans)Posterior/Caudal tail-end (inferior in humans)Median middleCentral part of a system nearest the middlePeripheral part nearest the surfaceProximal near the main mass of the bodyDistal away from the main mass of the bodySuperficial near the surfaceDeep some distance below the surfaceB. Planes and Axes:SAGITTAL PLANE longitudinal axis + dorsoventral axis Parasagittal any sagittal plane thats not medianFRONTAL PLANE longitudinal axis + mediolateral axis [L-R]TRANSVERSE PLANE dorsoventral axis + mediolateral axis [L-R]

C. BILATERAL SYMMETRY exhibited by all vertebrates Median sagittal plane divides the animal into approximately identical L-R halves Digestive tract only system that doesnt exhibit a symmetrical relation to median plane in adult stageD. METAMERISM: regular repetition of body parts along the anteroposterior axis Metamere/Segmment/Somite division of the body1. Homonomous segmentation segmentation into nearly like segments2. Heteronomous segmentation various segments differ from each other Condition derived from:i. Loss of segmentsii. Fusion of adjacent segmentsiii. Enlargement/reduction of segmentsiv. Loss of part in some segments and the retention in othersv. Structural changes among repeated parts

Gonads of hemichordates exhibit pseudometamerism Adult vertebrates internally and heteronomously segmented animalsE. CEPHALIZATION: centralization/localization of nervous structures and functions in the headF. Homology and AnalogyHOMOLOGY: intrinsic similarity indicative of common evolutionary origin Similarity of anatomical construction Similar topographical relations with to animal body Similar embryonic origin Similarity/identity of specific physiological function or mechanismANALOGY: similarity of general function or of superficial appearance not associated with embryonic origin/development Convergence analogous structures present striking similarity of appearance (adaptations) Divergence - closely related animals differ in general appearance due to different environments

Chapter 2: Phylum ChordataA. Characteristics of Chordates1. Notochord2. Dorsal hollow nerve tube3. Post-anal tail4. Pharynx pierced by gill slits (embryo/adult)

B. Classification of ChordatesPhylum ChordataSubphylum Urochordata (Tunicates) notochord found in tail of larvae (absent in adult)Ex. Pandosia (Sea squirt)Subphylum Cephalochordata notochord found from head to tail; (present in adult)Ex. Amphioxus / Branchiostoma Subphylum Craniata presence of head case (CRANIUM)Superclass Agnatha jawlessClass MyxiniOrder Myxiniformes narrow-mouthedEx. Myxine (hagfish)Class CephalaspidomorphiOrder Petromyzontiformes round-mouthedEx. Petromyzon (lamprey)Superclass GnathostomataClass Chondrichthyes cartilaginous skeletonSublcass Elasmobranchii exposed gill slits

Cold-blooded Aquatic AnimalsOrder Carcharhiniformes (sharks)Ex. Rhizoprionodon Order Rajiformes (rays & skates) dorsoventrally flatEx. Dasyatis, DipturusSubclass Holocephali concealed gill slitsEx. Chimaera (ratfish)Class Sarcopterygii (lobe-finned fishes) nostrils opening in to the roof of oral cavitySuperorder Crossopterygii w/ spiracle ; Hyostilic jaw suspensionSuperorder Dipnoi (true lungfishes) w/o spiracle; Autostylic jaw suspensionEx. Lepidosiren, Protopterus, NecoratodusClass Actinopterygii (ray-finned fishes) no internal openings of nasal sacSubclass Chondrostei w/ spiracleOrder Polypteriformes lungs opening ventralEx. PolypterusOrder Acipenseriformes lungs opening dorsalEx. Acpinser (sturgeon), Polyodon (paddlefish/ spoonbill)Subclass Neopterygii w/o spiracleOrder Lepisosteiformes Ex. Lepisosteus (gar pike) - w/ heterocercal tailOrder Amiiformes w/ homocercal tailEx. Amia (bowfin fish)Order Teleostei (typical bony fishes) w/ homocercal tail; w/o spiral valveEx. Box fish, Pinecone fish

Cold-blooded Aquatic / Terrestrial AnimalsClass Amphibia embryo w/o embryonic membrane with gills in some stages of life historyOrder Caudata w/ tailEx. Necturus (mud puppy)Order Anura (frogs & toads) w/o tailEx. Rana, BufoClass Reptilia embryo w/ embryonic membrane (amnion & alantois) w/ thick, dry, scaly skin gills lacking in all stages of life historySubclass Anapsida roofed skull w/o temporal vacuitiesOrder CheloniaEx. Chelone (turtles)Sublass Lepidosauria diapsid skull w/ two lateral temporal openingsOrder Rhyncocephalia teeth fused to jaw (w/o sockets)Ex. SphenodonOrder Squamata teeth set in socketsEx. Varanus (monitor lizard), Draco, gecko, snakes, skinkSubclass Archosauria diapsid skull w/ two temporal openings; tending to bipedal gaitOrder CrocodiliaEx. Crocodilus v-shaped snout

Warm-blooded TerrestrialAlligator u-shaped snoutClass Aves w/ feathers and uropygial glandSubclass NeornithesEx. Gallus (chicken), Anas (duck), Boteo boteoClass Mammalia w/ mammary glandSubclass Placentalia/EutheriaOrder Insectivora smooth brain w/ clavicle and clawed plantigrade feet; teeth w/ sharp cuspsEx. Suncus (shrew)Order Pholidota no clavicle; externally covered w/ imbricated horny scalesEx. Manis (pangolin)Order Chiroptera smooth brain w/ clavicle; w/ wing membranesEx. Rousettus (bats)Order Primates convoluted brain w/ clavicle; hairy mammalsOrder Rodentia w/ clavicle; clawed plantigrade feet, canines lackingEx. Mus (mice), ratsOrder Carnivora convoluted brain w/ reduced/absent clavicleprominent canineEx. Felis (cat), Canis (dog)

Chapter 3: Essential Features of Lower TypesPhylum Hemichordata Show even greater relationship with invertebrates than chordatesEx. Balanoglossus (acorn worm)Anatomy:

Parts & FunctionsProboscis used in burrowing into the sandProboscis Stalk attaches proboscis to inner dorsal surface of collarBuccal CavityGenital Ridges contains the gonadsGill pores not true gill slits (anterior dorsal side of branchiogenital region)Hepatic Caeca have some digestive functionInternal Anatomy (Salient points)Heart dorsal to the so-called notochordCentral blood sinus blood channelGlomerulus excretory organ

Phylum ChordataSubphylum Urochordata (Tunicates)External Anatomy

Internal AnatomyMantle encloses the viscera to which it adheres to soft body wall beneath test consists of outer epithelium & inner connective tissuePharynx serves as food-catching device & respiratory mechanism large thin walled bag connected to oral siphonAtrium cavity between pharynx and mantleGanglion constitutes the central nervous system Found dorsally behind the pharynxSubphylum CephalochordataEx. Amphioxus / BranchiostomaAnatomy: Sagittal Section

Cross sections

Female (x.s)Male (x.s)Parts and Functions:Cirri chemoreceptors used to search for foodMyotomes exactly 60 in number and used for movement (lateral movement)Wheel Organ catches food particlesHatscheks Groove & Pit secretes mucus to aid in catching foodVelum contains the mout of amphioxusPharynx serves as food-catching device & respiratory mechanismAtriopore exit of gametes and liquid wasteAnus exit of solid wasteNotochord serves as skeletal supportNeural Tube central nervous systemFin Ray supports the dorsal finEpibranchial Groove (endostyle) secretes mucus for food particles to adhere toEyes detects lightPigment Spot unknown function; does not detect light

Relationship of Amphioxus with a. Balanoglossids mode of formation of tongue bars and arrangement of skeletal rods of gill bars are similar wheel organ of amphioxus is homologous with preoral ciliary organ of balanoglossidsb. Tunicates Structures of pharynx (endostyle, peripharyngeal band, & epipharyngeal groove) are identical w/ tunicatesSubphylum CraniataSuperclass AgnathaCharacteristicsMyxini (hagfish)Petromyzon (lamprey)

Eyes-

Dorsal Fins-

Gill Slits12 pairs7 pairs

Nasohypophyseal CanalEnds blindly in the pituitary sacContinues beyond the olfactory sac

Buccal funnel-

Anatomy of Lamprey:

Parts and Functions:Gill Pouches used to respire by pumping water in and out through the gill slitsGill lamellae borne on the walls of the gill pouchesNotochord chief axial skeleton of lamprey Straddled by small separated arches (Lateral Neural Cartilages)Branchial Basket supports the gillsBuccal Funnel used to attach to fish as a suction cupPericardial Cavity contains the heart dorsal positioning of olfactory apparatus due to shifting of organs during development Larval stage = nasal sacs & hypophysis arise as separate invaginations on the ventral side Adult stage = development of buccal funnel brings the nasal & hypopyhseal invaginations dorsally and fuses them together

Chapter 4: External Anatomy and Adpative Radiation in GnathostomesClass ChondrichthyesSubclass ElasmobranchiiOrder CarcharhiniformesEx. Rhizoprionodon (shark) FUSIFORM (spindle-shaped) body offers little resistance to water Body covered in PLACOID SCALES Fins for locomotiona. Unpaired (median) finsi. Anterior and Posterior dorsal finii. Caudal fin = HETEROCERCALb. Paired (lateral) fins i. Pectoral finsii. Pelvic Fins In males: presence of Claspers used in mating (w/ sperm conducting groove) Ceratotrichia (dermal fin rays) supports all fins Presence of Lateral Lines along each side of the body, overlying the Lateral Line Canal used to detect water vibrations Head is triangular and somewhat flattened Rostrum Mouth bounded by upper and lower jaws Nostrils allow current of water to circulate through olfactory sac Oval eyes w/ immovable upper and lower eyelids Internal ears connected with the surface of the head via Endolymphatic ducts Gill slits communicates with the cavity of the pharynx (respiration) Spiracle 1st gill slit Cloacal aperture (anus) w/ Urogenital papilla seen within its walls Cloaca receives urinary and genital ducts, as well as the intestineOrder Rajiformes (skates and rays) DORSOVENTRALLY FLAT body due to bottom-dwelling habits Dorsal area covered in PLACOID SCALES consisting of an imbedded basal plate and projecting spine Ventral is void of scales Has Pectoral (enlarged) and Pelvic (reduced) fins; presence of claspers for males w/ anus

Head consists of: Rostrum dorsalEyes w/o lids Spiracle for respiration Mouth ventralNostrils Nasofrontal Process Oronasal Groove Gill SlitsSubclass HolocephaliEx. Chimaera (ratfish) Has smooth, silvery looking skin and an Opercular opening (w/c lacks skeletal support) Has large head and long HETEROCERCAL tail Males have Frontal Claspers fleshy projections at the summit of the head PLACOID SCALES on the headClass Sarcopterygii (lobe-finned fishes)Superorder Crossopterygii w/ spiracle and hyostilic Jaw suspensionSuperorder DipnoiEx. Lepidosiren (true lung fish) trunk covered in CYCLOID SCALES has a DIPHYCERCAL TAIL paired fins have retained their primitive position differ from other fishes by having internal nares nasal sacs opening to the roof of oral cavity w/ spiracle and autostylic jaw suspensionClass ActinopterygiiSubclass ChondrosteiOrder PolypteriformesEx. Polypterus has a DIPHYCERCAL tail covered in GANOID SCALES (rhomboid in shape) Fins Has small anal fin and long dorsal fin subdivided into finlets Paired fins retain primitive position Operculum supported by bones dorsally and joined ventrally by a membrane containing Gular Plates forerunners of the branchiostegal membrane and rays w/ spiracles and double nostrils near end of the mouth

Order AcipenseriformesEx. Acipenser (sturgeon) Barbels used as sense organs for food detection Has double nostrils Curious mouth bordered with sensory papillae Has degenerate jaws and teeth Covered with GANOID SCALES Has a HETEROCERCAL tail w/ slitl-like spiracles above each eye and operculum supported by a single boneEx. Polyodon (paddlefish/spoonbill) Rostrum is expanded into a broad, thin, spatulate structure provided w/ sense organs for detection of food has double nostrils and small spiracles Operculum lacks opercular bones and continues to the Branchiostegal Membrane w/o rays Gill rakers found on the gill arches Seperates food particles from mud Has a HETEROCERCAL tailSubclass NeopterygiiOrder LepisosteiformesEx. Lepisosteus (gar pike) Has hard shining GANOID SCALES and bony operculum Has very elongated tooth jaws forming a snout Median and paired fins w/ stout Lepidotrichia bony, flexible, jointed fin rays Has a HETEROCERCAL tailOrder AmiiformesEx. Amia (bowfin fish) Has double nostrils and a HOMOCERCAL tail Covered in CYCLOID SCALES Median and paired fins supported by LepidotrichiaOrder Teostei (typical bony fishes)Ex. Box fish & Pinecone fish Has a HOMOCERCAL tail Body covered in CYCLOID Scales Lateral line is present and has large eyes w/o lids Ears are situated behind the eyes Head: Operculum gill cover; supported by opercular bones Branchiostegal membrane supported by branchiostegal rays Gill arches (4) curved structures, each bearing a gill (w/ gill rakers) Used for respirationCavity of pharynx is in communication w/ the exterior through the Gill slits Fins are supported by Lepidotrichia Has an anal opening and urogenital papilla (projecting from depression behind anal opening)difference w/ elasmobranchs is that the intestine & urogenital system of the perch open separatelyAdaptive Radiationa. Body forms and shape:High, laterally-flattened body = for moving among dense growthsb. Suckers Ventral = to attach to rocks Dorsal = to attach to other fishes (employed by sharks) c. Enlargement of pectoral fins = for flyingd. Presence of photophores = to attract fish w/c serve as foodSummary:

Class AmphibiaOrder CaudataEx. Necturus (mud puppy) Skin is naked, slimy, and void of scales External nares communicate w/ mouth cavity via internal nares Has small eyes and internal ears (3) External gills used for respiration along w/ lungs Do not correspond to gills of fishes Gular fold fold of skin passing transversely across the throat w/ (2) pairs of appendages correspond to pectoral and pelvic fin of fishes Forelimb: upper arm, forearm, wrist (bent downward), & hand (bent forward) Brought about by torsion of upper arm Hindlimb: Thigh, shank, ankle, & foot In primitive (supine) position has only 4 digits (1st digit missing) has flattened tail bordered by tail fin (w/o fin rays) w/ anus and cloacaOrder AnuraEx. Rana & Bufo (frogs and toads) has tympanic membrane (eardrum) covering the middle ear (5) digits with webbed feetClass ReptiliaSubclass AnapsidaOrder CheloniaEx. Chelone (turtle) Skin shows reptilian cornification w/ Externals nares allows to breath air w/ only slight exposure above water jaws lack teeth but are clothed w/ hard horny beaks Shell: consists of large horny shields and bony plates Carapace Plastron Lateral bridges connects carapace w/ plastron Position and torsion of limbs similar to lizards w/ rounded anusSubclass LepidosauriaOrder RhyncocephaliaEx. Sphenodon most primitive living reptile internal (skeletal) primitive characteristics most noticeable feature: mid dorsal row of spinesOrder SquamataEx. Varanus (monitor lizard), Draco, gecko, & skink clothed w/ non-detachable horny scales, plats, and tubercules tetrapod body form: head, neck, trunk, and long tail Head shields enlarged scales/plates on the head External nares opens to mouth cavity Has external ears and middle ear (eardrum/tympanic membrane) Gular folds = can be extended to form a dewlap Parietal eye serves some optic function Skin folds erected/displayed in courtship or battle Has 5 digits and foot retained primitive position Femoral pores secretes yellowish waxy material (for copulation) Has anus and pre-anal poresEx. Snakes Lacks limbs and eyelids Poisonous snakes have Pits temperature detectorsSubclass ArchosauriaOrder CrocodiliaEx. Alligator & Crocodilia Have upper (w/ bony support) and lower eyelids; nictitating membrane Covered by large horny thickenings Class AvesSubclass NeornithesEx. Gallus (chicke), Anas (duck), Boteo boteo Clothed w/ a covering of feathers Remiges (wings): 1, 2, and 3 (humerals)Flight feathersContour Retrices (tail)FeathersCovert feathers covers general surface area of the body Filoplumes (hair feather) hair-like processesFeather follicles deep pits into w/c contour feathers are set Head: Beak jaws incased in horny sheath; teeth absent Cere cushion-like protuberance at the base of the upper beak External nares External auditory meatus narrow passage leading to the middle ear External ear elevated skin fold around meatus Large eyes w/ upper & lower eyelids Trunk: Keel of breastbone to w/c the wing muscles are attached Paired limbs:a. Wing homologous to forelimbs of other vertebrates In primitive position when extended Consists of upper arm, forearm, and fused wrist &hands b. Hindlimb clothed partially w/ feathers and partially w/ horny scales Has (4) digits: 5th is absent1st is directed posterior for perching Anus found at the base of the tail Uropedium where the Uropygial Gland is seenSecretes oil used for preening feathers Adaptive radiation:a. Body form & proportionsb. Relative length and shape of wingsc. Types of beaks and feet -= difference in habitat and foodClass Mammalia Warm blooded vertebrates provided with hair and Mammary glands for nourishing the young w/ milk

Subclass PlacentaliaOrder CarnivoraEx. Felis (cat) Body is clothed Fur closely set hairs Whiskers/vibrissae have rich nerve endings that serve as tactile organs Head: Facial region in front of eyes Cranial region enlarged posterior region External nares overhung by the mobile nose Has eyes with upper & lower lids and a nictitating membrane Pinna long & flexible external fold at the rim of the external auditory meatus; sound catching device Trunk a. Anterior chest/thorax Teats / nipples the (4-5 pairs) openings of mammary glandsb. Posterior abdomen Limbs terminate in clawed digits: 5 in front & 4 behind ( 1st hind toe is absent) Prone position crossing of the two bones of forearm Supine position parallel position of the two bones of forearm Walking:i. Digitigrade walking on digits ( rabbit & cat)ii. Plantigrade walking on whole sole of foot (man)iii. Unguligrade walk on their nails ( horses & cattle) Perineum region w/c includes anal & urogentila openings Inguinal glands source of characteristic odoriferous secretions (in rabbits) In females: opening & labia major together constitutes the vulva In males: penis transmitting sperm to femaleScrotum where testes are located (prepuce/foreskin in cats)Order PholidotaEx. Manis (pangolin) Has Clawed feet for opening ant nests; long pointed snout and extensile tongue Spines are mingled with the fur and a tail is wanting; w/ protective armor Lays eggs Milk glands open directly on the skin by several aperturesAdaptive Radiation:a. Rousettus (bats) great lateral expansions (wing membranes) = for true flight large ear pinnae b. ungulates hoofs = modified toenails c. aquatic mammals blubber = thick layer of fat under the skin to retain body warmth

Chapter 5: General Features of Chordate DevelopmentA. Chordate Eggs and DevelopmentSpecimensType of EggType of CleavageBlastulaGastrulaFromation of Germ layers, notochord and neural tube

Anphioxus & MammalsISOLECITHALw/ little yolk, evenly distributedHOLOBLASTIC, EQUAL egg divides and produces a number of approximately equal cells Blastomeres (cells) Blastocoel (cavity)

Germ Layers: Ectoderm & Entoderm Archenteron (gastrocoel) primitive intestine Blastopore opening of archenteron to the exterior Coelomic (mesodermal) sacs Mesoderma. Somatic (parietal) mesoderm outer; in contact with ectodermb. Splanchnic mesoderm inner; in contact with entoderm Coelem (body cavity) cavity of the pouches Neural Tube primordium of brain and spinal cord Notochord primitive axial skeleton Archenteron

AmphibiansTELOLECITHALw/ moderate amt. of yolk accumulating in half of the eggHOLOBLASTIC, UNEQUAL cells withdraw from the center, producing blastula w/ reduced blastocoel and a wall several layers thick Animal Hemisphere (micromere) contains majority of protoplasm Vegetal Hemisphere (macromere)contains most of the yolk Blastocoel Germ Layers: Ectoderm & Entoderm Archenteron (gastrocoel) Blastopore Yolk Plug enclosed yolk-bearing cells Chordamesoderm roof of archenteron Mesodermc. Somatic (parietal) mesodermd. Splanchnic mesoderm Coelom (body cavity) Notochord Neural tube Archenteron

Birds, Reptiles, & egg-laying MammalsTELOLECITHALw/ enormous amt. of yolk and protoplasm concentrated on small disk (Germinal Disk)MEROBLASTIC small germinal disk undergoes cleavage Blastoderm (disk of cells on the surface of the yolk) Blastocoel slight slit between blastoderm and yolk Germ Layers: Ectoderm & Delaminated entoderm Archenteron will disappear Primitive Streak represents the formation of the roof of archenteron source of notochord and mesodermal sheets Hensens Node represents blastopore

Formation and Development:in Amphioxus, Mammal, and amphibian eggs

InvaginationcleavageEgg cell Blastula Gastrula Neural plate stage

Neural tube stageNeural groove stageIn Reptilian and bird eggs

cleavageInvaginationGastrulaBlastoderm Egg cell

Delamination(Germinal disk)

Development of Amphioxus Egg:Gastrulation

Neurulation

Neural plate stage Neural Groove stageNeural tube Stage

Development of Amphibian EggGastrulation

Early GastrulaMiddle GastrulaLate Gastrula

Neurulation

Neural plate stage Neural groove stageNeural tube stage

Fate of Germ Layers:Ectoderm: Gives rise to neural tube (CNS) Forms the external layer of the skin and all its derivatives Gives rise to the sensory part of all sense organs Lining membrane of all nasal & mouth cavities, anus, glands of skin, enamel of teeth and lens of the eye Cranial Nerves & melanophores [from the neural crest]

Entoderm: Primitive intestine Forms epithelial lining of intestine and all its derivatives: Respiratory system: Gill pouches & gills, larynx Digestive system: liver, gall bladder & bile duct, pancreas

Mesoderm:

Sclerotome (vertebral column)EpimereDermatome (dermis of the skin)Myotome (muscles)

MesodermMesomereKidneys, reproductive organs &ducts

Somatic mesodermparietal pericardiumHypomereSplanchnic mesodermvisceral pericardiumCirculatory system

Somatic mesoderm + Ectoderm = Somatopleure (body wall)Splanchnic mesoderm + Endoderm = Splanchnopleure (intestinal wall) Mesothelium parts of the mesoderm w/c dont become mesenchyme but retain epethilial characteristicsMesenchyme Gives rise to all connective tissues of the body including cartilage and bone Smooth muscles Blood cells, blood vessels, lymph vessels & glands1. Sclerotome mesenchyme cells w/c migrate to a position around the notochord2. Dermatome mesenchyme cells w/c migrate to underside of ectoderm3. Myotome - separated from each other by myoseptum

Chapter 6: Comparative Anatomy of the Skin and ExoskeletonA. General Considerations of the Skeleton and TermsSkeleton includes all of the hardened portions of the bodies of animals1. Exoskeleton (external skeleton) Derived from skini. Epidermal = derived from epidermis (ectodermal origin)ii. Dermal = derived from dermis (mesodermal origin - dermatome) Forms covering and protective layer outside the body2. Endoskeleton (internal skeleton) Derived from innerwall of epimere (sclerotome) Support & framework of the body and place of attachment for voluntary muscles Bone fibrous connective tissue arranged in lamellae, impregnated with salts, containing bone cellsDentine chief constituent of teeth Dentinal tubulesEnamel epidermal in origin (stratum germinativum) Shiny outer coat of teeth

B. Structure of the SkinSkin surface covering easily separable from the underlying muscular layer of body wall1. Epidermis Outer layer composed of stratified epithelial cells Outermost layer undergoes KERATINIZATION (flattening and hardening into a horny stratum) Stratum corneum keratinized stratum Stratum Germinativum active portion of the epidermis that proliferates (Columnar cells) Stratum Lucidum & Stratum Granulosm (in humans and birds) seperates the stratum corneum from the stratum germinativum2. Dermis Inner layer composed of connective tissuea. In humans: fibrous connective tissue Dermal Papillae Sweat glands long, hollow tubular glands w/c secrete sweat as means of lowering body temp. Sebaceous glands - solid epidermal ingrowths w/c secrete an oily substance for lubricating the skin & hairs ; protection from water Mammary glands*b. In frogs: Statum Laxum next to epidermis; consisting of loose open connective tissuei. Cutaneous glands really part of stratum germinativum, invaginated to loose protion of dermis produces mucous and other protective secretionsii. Chromatophores (pigment cells) dark irregular branching cells beneath the epidermis Melanophores black protein pigment (melanin) Xanthophores yellow to red fatty pigments Guanophores reflect light and produce white, metallic/iridescent colors (guanine crystals) Epidermal pigment is usually of diffuse or granular type; dermal pigment nearly always inside chromatophores Stratum Compactum layers of dense, parallel wavy fibers

C. ExoskeletonsI. Exoskeleton of Fishes Clothed w/ scales w/c are dermal in origin1. Placoid Scale characteristic of elasmobranchs; giving rough texture to skin (shagreen shark skin) Homologous w/ vertebrate teeth Basal Plate & Projecting Spine2. Ganoid Scale characteristic of Polypetrus, Acipenser, Polyodon, Lepisosteus Hard, shiny rhomboid plates Immovably joined to each other by Peg-and-Socket Arrangement3. Cycloid Scale characterteristic of Dipnoi, Amia, and Teleosts Imbricates arrangement Fluted inner half Concentric ridges used to determine age and growth rate of fish4. Ctenoid Scale Fluted inner half Concentric ridges Teeth Dermal Fin Rays:1. Ceratotrichia Found in elasmobranchs and Holocephali Slender, flexible unjointed fin rays consisting of fibrous material2. Lepidotrichia Found in Actinopterygii, Branched, jointed rays composed of bone Joints have been shown to be homologous with scales of the same fish

II. Exoskeleton of Reptiles Clothed in horny exoskeleton marked of into scales and scale-like areas Epidermal in origin (thickening of stratum corneum)Exoskeleton of Turtles Composed of Scutes (epidermal thickenings) and bony Plates (dermal structures)a. Carapace

Dorsal Ventral

b. Plastron

Dorsal VentralIII. Exoskeleton of Birds Clothed in feathers on the greater part of the body, scales & claws on the feet, and horny beaks (epidermal in origin) No dermal exoskeleton Feathers homologous to reptilian scalesa. Down Feathers (Plumules) Constitute fluffy covering of young birds and bases of contour feathers in adult birds Development of feather resembles that of reptilian scales which involves a nutritive dermal papilla and an epidermal thickening Quill Barbs (w/ hooks) Barbulesb. Contour Feathers Common type of feather w/c covers the bodies of birds

Difference in development of down feathers and contour feathers:Plumules = barbs spring in a circle from the top of the quillContour feathers = barbs spring from the sides of the quillc. Hair Feathers (Filoplumules) Visible on the plucked bird Consists of: Shaft Barbs BarbulesPterylae (feather tracts) areas with feathersApterylae areas without feathersIV. Exoskeleton of Mammals Exoskeleton primarily consists of hair Hair (epidermal origin) Hair follicle pit in the skin Root part of the hair inside the follicle Inner root sheath white coat w/c clings to the roots of hairs when pulled Shaft exposed part of hair Cuticle surface layer of hair Cortex between cuticle and medulla Medulla central strand of degenerate materialTypes of hairs:Facial vibrissae large tactile hairs on the faceBristles found in spiny ant-eatersGuard hairs coarse hair scattered on furAristate hairs smaller, numerous w/ thickened flattened hairsWool/fur fine, short, wavy hairs Scales of mammals Armor composed of both epidermal scutes and dermal plates (like turtles) Claws, nails, hoofs, and horns Composed of compressed layers of stratum corneum Covers the last joint of the digit (phalanx) Claws, Nails and HoofsNails:

Hoofs:

Claws:

True Horns and Antlers True horns epidermal outgrowths hollow Antlers dermal outgrowths attached to frontal bone