Zoology Exam 2

Zoology Pennwest Edinboro: Exam 2- Good Luck!

Phylum Chaetognatha

-arrow worms

-132 spp.

-marine predators 1-12 cm. planktonic

-teeth and 4-14 pairs of curved spines

-tripartite coelom

-simultaneous hermaphodites via spermatophores to partners neck or self fertilization

-eggs planktonic and direct development

Phylum Rotifera

-wheel bearers

-2467 spp.

-mostly freshwater, some marine, and some parasitic

-interstitial and floating spp. some colonial

-ciliated corona and grinding mastax

-1-4 sticky toes

-syncytial epidermis with 900-1000 nuclei

-complete digestive tract and pair of protonephridia

-dioecious but many parthenogenic spp. (95% teste 5% integumentary) amitotic vs mictic eggs

mictic eggs

halpoid. produce M or F

amitctic eggs

diploid. produce F

Phylum Acanthocephala

-1330 spp.

-parasites of vertebrate intestines

-retractible hooked proboscis

-two hydrostatic lemnisci→everts proboscis

-no digestive tract & syncytial integument

-pseudocoloem

-dioecious copulators: acanthor larva shed in feces

Phylum Mesozoa

-mesozoans

-147 spp.

-PARASITES: cephalopod nephridia and various marine inverts

-20-30 outer somatic cells, inner reproductive cells

-no digestive tract

-asexual and sexual reproduction with larval stages

Phylum Entoprocta

-entoprocts/goblet worms

-171 spp.

-stalked sessile animals(solitary or colonial)

-mostly marine→2 freshwater spp.

-mouth and anus of u shaped gut both inside lophophore of ciliated tentacles. pair of protonephridia

-pseudocoloem

-solitary spp.→monoecious colonial spp.→dioecious trochophore larva

Phylum Ectoprocta

-bryozoans/moss animals

-5458 spp.

-stalked or encrusting sessile animals

-mostly marine some freshwater spp.

-almost all colonial, with zooids in secreted zoecia

-lophophore withdraws into zoecium. anus outside of lophophore

-nephridia excretes coelomocytes full of wastes

-mostly monoecious→asexual statoblasts

-fertilization internal or external→many brood in ovicells

-

zooids

lives within a box-shaped compartment

zoecia

house that the animal secretes (calcareous, chitinous, or gelatinous)

Phylum Brachiopoda

-lamp shells

-406 spp.

-solitary marine sessile animals

-much better represented among fossils

-bivalve shell (ventral and dorsal)

-some have fleshy pedicel (anchor)

-two armed lophophore

-3 part enterocoelic coelom

-open circulatory system

-moslty dioecious with external fertilization

Phylum Phoronida

-phoronoids

-19 spp.

-marine worms up to 30 cm

-secreted chitin lines burrow

-lophophore is curved and ridged. anus outside of lophophore

-3 part partitioned true coelom (enterocoely)

-circulatory system largely closed. 2 nephridia

-monoecious or dioecious. some via fragmentation mostly externally fertilized, but some internal via lophophoral spermatophores with brooding on female lophophore

-ciliated hooked actinotroch larva

Phylum Nemertea

-ribbon worms

-1385 spp.

-mostly marine worms

-hydrostatic rhynchocoel houses proboscis→neurotoxins delivered via stylet

-complete digestive system, nerve cords with transverse nerves, closed circulatory system→not heart vessels contract

-several protonephridia

-asexual fragmentation, moistly dioecious external fertilizers, some hermaphrodites

Lineus longissimus

bootlace worm, Northern European coasts, up to 55m in length and up to 10 mm in width

Phylum Mollusca

-87,409 spp.

hypothetical molluscan ancestor:

-hypodermis mantle with mantle cavity housing gills

-hydrostatic foot

-scraping radula

-small true coelom surrounds heart of open circulatory system

-simple nerve cords, few ganglia→circusesophageal

-ciliated trochophore and shelled veliger larvae

Classes Caudofoveata and Solenogastres

-marine elongate worms

-no shell but some fossil spp. had shells

-formerly united in class Aplacophora (no shell)

-scales and calcareous spicules in skin

-most have radula (lost in solenogastres)

-foot is lost in caudofoveates, a vestige in solenogastres

-reduced posterior mantle cavity

-pair of gills in caudofoveates, none in solenogastres

caudofoveates dioecious, solenogastres monoecious

Class Polyplacophora

-chitons

-marine; elongate foot with mantle cavity and gills to either side

-8 piece (rarely 7) shells

-scraping radula

-trochophore metamorphoses into adult

Class Monoplacophora

-monoplacophorans

-marine “living fossils”

-single shell

-broad, hydrostatic foot

-serially repeated gills, gonads, heart Ostia, nephridia, and transverse nerves

-true metamerism or pseudometamerism

Class Gastropoda

-snails, slugs, conchs, whelks, abalones…

->70% of the phylum

-marine freshwater and terrestrial

-single valve shell in most, often coiled

-torsion in larval development

-radula usually present

-gills in some, lungs in others

-monoecious (terrestrial) or dioecious

-copulate or transfer spermatophores

-eggs float, or in masses or capsules

-trochophore & veliger larvae

Class Cephalopoda

-squids, cuttlefishes, octopi, and chambered nautili

-foot→head and tentacles

-shells buoyant in nautili, internal in squids (squidpen) and cuttlefishes (cuttlebone), lost in octopi

-swim by ejecting water from the mantle cavity

-closed circulatory system with 3 hearts

-camera eyes

-radula and keratinized beak

-spermatophores transfer via hectocotyl

Class Bivalva

-freshwater and marine

-2 shells joined at dorsal hinge: adductor muscles close shell

-mostly filter feeders fed by ciliary gill currents via incurrent and excurrent siphons

-no radula

-most move slowly via hydrostatic foot (oysters:sessile) (scallops:swim via adductors)

-trochophore and veliger larva

-parasitic glochidium larva in freshwater mussels

Class Scaphopoda

-Tusk shells

-marine burrowers up to 25cm

-curved tubular shell opens above and below

-mantle cavity’s respiratory current drawn in and out of top hole by cilia and muscular movements

-lower openings captacula (foot and tentacles) for feeding in sediments and respiration

-radula present

Phylum Cycliophora

-first sp. described in 1995 (2 spp.)

-symbionts on lobster oral appendages

-acoelomate

-ring of oral cilia and u shaped digestive tract

-asexual budding

-sexual dioecious larvae

-disperse as lobster molts

Phylum Annelida

-16,349 spp.

-metamerism (repeated segments (metameres))

-septa confine hydrostatic movements (internal partitions between segments)

-circular and longitudinal muscles

-most have setae→used for traction or anchoring

-terminal mouth and anus

-schizocoelous euecoelom (solid mass of mesoderm splits to make coelom)

-closed circulatory system

-dorsal vessel: anterior flow (vein)

-ventral vessel: posterior flow (artery)

-ventral nerve cord, dorsal anterior brain

-trochophore larvae in marine spp.

Annelid Phylogeny

polychaete- many setae; marine

oligiochaete- few setae; freshwater + terrestrial leeches

Class Errantia

-motile polychaetes

-marine crawlers (tubeless)

-fleshy parapodia→legs hydrostatic

-highly developed eyes and statocysts on head

-bundles of setae on parapodia

-saws

-moslty dioecious spawners

Palolo Worm of American Samoa

-Epitoke: seasonal gamete producing segments

-break free of atoke segments for spawning

-only for a few hours a year in the fall after midnight

-eaten raw, fried in oil, baked in bread, or on pizza

Class Sedentaria

-tube dwelling polychaetes, oligiochaetes, and leeches

-marine-tube dwellers; terrestrial and freshwater spp.

-few setae in pairs, or none

-simultaneous hermaphrodites

-clitellum: swollen band involved in reproduction

-mucus for sperm transfer

-chitinous cocoon around eggs

-direct development→leeches and earthworms

Leeches

-mostly freshwater

-flattened with narrow metaverse, generally aseptate and lacking setae

-few anterior septa and setae in one group

-predators or blood sucking parasites

-3 jaws

-2 suckers; posterior and anterior

-salivary anticoagulant

-simultaneous hermaphrodites

-direct development in egg cocoons

Former Phyla relegated to Sedentaria

-Phylum Echiura

-Phylum Pogonophora

-Phylum Sipuncula

P. Echiura

-spoon worms (173 spp.)

-feed using ciliated proboscis

-trochophore larvae (ciliated top)

-males inhabit uterus of female in one sp.

P. Pogonophora

-beard worms (207 spp.)

-absorb nutrients through skin and live off bacteria mutualists

P. Sipuncula

-marine burrowers (205 spp.)

-anterior introvert

-u shaped coiled gut with anus on side

-hydrostatic schizocoelous eucoelom

-ventral nerve cord

-two nephridia

-asexual fission and regeneration

-dioecious with external fertilization (1 sp. monoecious)

-most have trochophore larva (some direct development and some have pelagosphera larva)

Phylum Nematoda

-roundworms

-20,024 spp

-free living marine, freshwater, and terrestrial spp; plant & animal parasites

-collagen in cuticle antagonistic to longitudinal muscles

-pseudocoelom

-complete digestive tract

-eutely -set # of cells when adult

-nerve ring anteriorly and dorsal and ventral nerve cords

-dioecious; male has copulatory spicules to aid in keeping female opening open

-oviparous, direct development (4 molts of the cuticle)

Phylum Nematomorpha

-horsehair worm

-356 spp.

-aquatic adults

-juveniles parasitize hemocoels of arthropods

-insects, spiders, pillbugs, hermit crabs

-some have second invert host

-induce water finding behavior when ready to emerge

-cuticle, pseudocoelom, and longitudinal muscles

-vestigal digestive tract

-absorb nutrients, even as adults

-ventral nerve cord

-no organs for gas exchange, circulation, or excretion

-dioecious

-internal fertilization and oviparity

-nematomorph larva penetrates new host

Phylum Loricifera

-”corselet bearer’

-46 spp.

-marine interstitial animals (<400 μm)

-plated lorica into which the head retracts (corselet)

-scalids: spines on head (setae-like)

-psuedocoelom

-2 protonephridia

-dioecious, internal fertilization

-higgins larva has adhesive toes (some spp. the larva is parthenogenic)

Phylum Kinoryncha

-kinorynchs or mud dragons

-346 spp.

-marine interstitial

-13 zones: retractible proboscis, neck, and 11 body zones with scalds→(like setae)

-anchors and chemo-/mechanoreceptive sense organs

-chitinous cuticle, reduced eucoelom, and longitudinal muscles

-crawl using introvert

-brain and ventral nerve cord

-2 protonephridia

-dioecious

-internal fertilization

-oviparous egg cases

-11 segmented juvenile molts 6 times, adding 2 zonites

Phylum Priapulida

-penis worms

-22 spp.

-marine burrowers

-retractible introvert

-terminal anus

-hollow caudal appendages may be respiratory or chemosensory

-ventral nerve cord

-protonephridia

-dioecious with external fertilization

-larvae have lorical coverings (similar to adult loriciferans)

Phylum Onychophora

-velvet worms

-235 spp.

-terrestrial tropical animals

-metameric and hydrostatic (13-43 pairs of hydrostatic lobopods with chitinous claws)

-antennae with eyes at bases

-slime glands of oral papillae capture prey

-open circulatory system

-coxal glands release urine at base of lobopods

-dioecious with spermatophores deposited on females back→sperm bore through skin

-placentally or aplcentally viviparous or oviparous

-direct development

Phylum Tardigrada

-water bears or moss piglets

-1461 spp.

-microscopic animals that live in water film on mosses and lichens

-four pairs of legs

-piercing pair of stylets and sucking pharynx

-ventral nerve cord, dorsal brain (circumesophageal)

-eucoelom and dioecious

-3 excretory malphigian tubules open to gut

-copulate or external fertilization of eggs in shed cuticle of female→some spp. parthenogenic

-directb development

-cryptobiosis: dehydrated state for up to 10 years (tun)

Phylum Arthropoda

-1,177,044 spp.

-tagmata:

head-thorax-abdomen

cephalothorax-abdomen

head-trunk

-cuticle made of chitin which is thinner at joints

-appendage specialization

-almost all dioecious

-copulation or spermatophore transfer in almost all

Arthropod Internal Anatomy

-Dorsal brain, ventral nerve cord with segmented ganglia

-reduced eucoelom

-gills in aquatic spp.

-tracheal system and spiracles in terrestrial spp. or book lungs

-open circulatory system→heart with pairs of ostia

-coxal glands and/or malphigian tubules

-ommatidium make up a compound eye→1 inner cell with 6 outer cells

-84% of animal kingdom

Class Merostomata

-horseshoe crabs (4 marine spp.)

-chelate appendages

-chelicerae

-pedipalps

-4 pairs of legs

-Abdomen: genital opercula and 5 pairs of book gills

-Telson for uprighting

-coxal glands→last pair of legs

-beach spawners with egg capsules

Class Pycnogonida

-sea spiders

-1394 marine spp.

-elongate proboscis, chelicerae, pedipalps, 4 pairs of legs

-exdternal fertilization

-males in some spp. brood on ovigers

-protonymphon larva (3 pairs of appendages)

Class Arachnida

-spiders, scorpions, psuedoscorpions, daddy longlegs,ticks, mites, etc

-95,851 spp.

-chelicerae→fangs in spiders

-pedipalps→spermatophore transfer in males and pincers in scorpions and pseudoscorpions

-4 pairs of legs

-pedicel: cephalothorax/abdomen constriction in spiders→absent in daddy longlegs

-capitulum: projecting head of ticks and mites

Arachnid Silk

-spiders mostly, but also pseudoscorpions and mites & insects & miyriapods

-abdominal glands open via spinnerets

-strong elastic protein

-webs, prey wrapping, draglines, sperm webs, egg cases, and balloons

Subphylum Myriapoda

-tagmata= head + trunk

-loss of compound eye

Class Chilopoda

-centipedes

-3145 spp.

-mandibles & 2 pair maxillae

-venemous maxillipeds with fangs→1st section of trunk

-15-170 pairs of legs (30-340 legs)

-active predators

-spermatophore transfer & some brood

-hatchlings typically have reduced number of legs

Class Diplopoda

-millipedes

-13,179 spp.

-mandibles and 1 pair maxillae

-up to 100 diplosegments have 2 pairs of legs, 2 pairs heart ostia, 2 ventral ganglia, 2 pairs of spiracles (1st segment is not diplosegment)

-herbivores and scavengers

-copulate with gonopods (modified legs) (males in 7th segment) and brood

-hatchlings have 3 pairs of legs

Class Paurapoda

-paurapods (sister to Diplopoda)

-995 spp.

-<1.5 mm

-most have no heart or tracheal system

-scavengers, biramous antennae, mandibles & 1 pair of maxillae

-9-11 pairs of legs on double segments

-spermatophores

-hatchlings have 3 pairs of legs adding legs with each molt

Class Symphyla

-symphylans or garden centipedes (sister to Chilopoda)

-231 spp.

-pigmentless, eyeless, herbivores and detritus feeders

-<8mm

-mandibles and 2 pairs of maxillae

-10-12 pairs of legs on 15-24 segments

-spiracles on head only

-spermatophores, but external fertilization like hotshot crabs & sea spiders

-hatchlings have 6 pairs of legs adding with each molt

Subphylum Crustacea

-biramous 2nd antennae

-2 pairs maxillae

-naupilus larva

-2nd pair of antennae

Class Ostracoda

-ostracods or seed shrimp

-7581 spp.

-bivalve carapace (chitin or CaO4)

-among dominant zooplankton, freshwater and marine and also nocturnal characteristics

Class Branchiura

-fish lice

-32 spp.

-fish ectoparasites

-2nd maxillae modified as suction cups

-4 pairs thoracic appendages

Class Pentastomida

-tongue worms

-6 spp.

-formerly Phylum Pentastomida

-lung parasites of amniote vertebrates

-fish or small mammal intermediate host

-unsegmented

Class Branchiopoda

-fairy, brine, tadpole, clam shrimp; water fleas

-1680 spp.

-legs double as respiratory surfaces

-often have a carapace

-among dominant zooplankton, freshwater and marine

-median eye in water fleas

Class Copepoda

-copepods “oar foot”

-15,068 spp.

-among dominant zooplankton, freshwater and marine

about ½ are ecto- or endoparasites of fish, inverts, or marine animals

-median eye

-tapered abdomen

Class Thecostraca

-barnacles

-472 spp.

-calcareous plates surround sessile adults with bivalve carapaces
-some parasitic

-antennae→cement glands

-6 pairs of biramous cirri with setae

-simultaneous hermaphrodites

Class Malacostraca

-shrimp, crayfish, lobsters, crabs, krill, scuds, pillbug

-43,466 spp.

-marine, freshwater, and terrestrial

-cephalothorax and abdomen

-typically 8 thoracic segments, 6 abdominal segments

-chelae: pincers of crabs, crayfish & lobsters

-crabs: abdomen reduced and folded under

Subphylum Hexapoda

-tagmata= head, thorax, abdomen

-6 legs

-unique tracheal system

Class Entognatha

-entognaths

-10,380 spp.

-coneheads, springtails, and bristletails

-<10mm, most <5mm

-mandibles and 2 pair of maxillae extend from gnathal pouch

-antennae have musculature in every segment

-wingless (not lost, though)

-many are eyeless

Class Insecta

-insects

-983,560 spp.

-mostly terrestrial and aquatic, few marine

-3 pairs ectognathous mouthparts

mandible

maxillae

unpaired labrum

-labium (fused 2nd maxillae)

-antennal musculature only in 2 basal segments

-most have 2 pairs of wings (2nd and 3rd thoracic segment)

-meso and metathoracic

-cuticular outgrowths

Insect Metamorphosis

-direct development in primitive wingless spp.

-winged insects: larvae with instars→divided between 2 successive molts

-hemimetabalous or incomplete metamorphosis→nymph or naiad instars gradually develop wings

-holometabolous or complete metamorphosis→larvae>pupa>adult

Deuterostomia 1 & Bilatera

-complete digestive system

-anus first

-true body cavity→eucoelomate→enterocoely:pocket of gut breaks away→mesoderm

Deuterostome Phylogeny

echiniodermata

hemichordata

chordata

Phylum Echinodermata

-echinoderms

-11,735 spp

-strictly marine

-5 part symmetry as adults (pentaradial symmetry)

-water vascular system of podia (tube feet) along ambulacral grooves

madreporite, ring canal, lateral canals

primitively: passing food to mouth

derived: locomotion

-ossicles (tiny bone)

-pedicellariae: microscopic pinchers (sea star and sea urchins)

-simple nerve ring and poorly developed sense organs

-mostly dioecious, typically with external broadcasting of gametes

-larvae bilateral with tripartite coelom

Class Crinoidea

-sea lillies and feather stars

-sessile with stalk (sea lillies) & holdfast at bottom

or

-sedentary swimmer perched on cirri (feather stars)

-five branching arms with upward facing ambulacral grooves for filter feeding

-U shaped digestive tract

-No spines or pedicellariae

Class Asteroidea

-sea stars and sea daisies

-5 or more arms

-numerous small ossicles and spines

-numerous pedicellariae- lobster claw-like for protection against settling larvae

-mouth ventral, anus dorsal

-paired podia in ambulacral groove→ primarily for locomotion but may also assist in feeding with eversible forward part of stomach

-autotomy and regeneration of arms (replicate into 2 organisms if split in half)

-bipinnaria larva becomes brachiolaria with ciliated arms

Sea Daisies

-3 spp.

-no arms; podia at margin

-2 concentric ring canals in WVS

-originally classified in new class, Concentricycloidea in 1996 but nested phylogenetically with Asteroidea

Class Ophiuroidea

-brittle stars and basket stars

-5 elongate arms with spaces in between at central disk→highly branched in basket stars

-podia used in filter feeding

-locomotion via rapid whip-like arm motions→slower in branched baskets stars

-large articulating ossicles in arms

-5 jaws make star shaped mouth

-10 bursae for gas exchange→around mouth→bursal slits

-asexual fission

-some brittle stars are monoecious

Class Echinoidea

-sea urchins, heart urchins, and sand dollars

-endoskeleton and integrated test

-aristotles lantern in sea urchins and sand dollars

-sand dollars also feed with podia of WVS

-secondary bilateral symmetry in heart urchins and sand dollars

-pedicellariae (sea urchins)

-locomotion:

sea urchins: spines and podia→soft & flexible (spines swivel at base)

heart urchins: spines only

sand dollars: spines only

Class Holothuroidea

-sea cucumbers

-elongate echinoderms that lay on their sides

-very reduced ossicles in leathery skin

-tentacles surrounding the mouth are modified podia of WVS

-locomotion via 3 well-developed rows of tube feet (other 2 are vestigial)

-respiratory trees internally for gas exchange (ass breathers)

-self defense via discharge of toxic cuverian tubules, digestive tract, and/or gonads

Phylum Hemichordata

-acorn worms

-139 spp.

-marine worms and sessile colonies

-to 2.5m; mostly «1m

-deposit feeders with ciliated proboscis

-in mouth out gill slits

-food ensnared in mucus

-respiration mainly at gill slits

-collar opens to expose mouth

-tripartite coelom

-ventral and dorsal hollow nerve cord

-mostly dioecious

-tarnaria larva also tripartite

Pterobranch Hemichordates

-26 spp.

-colonial (budding)

-only a few mm in length

-proteinaceous tubarium (collagenous tube secreted)

-proboscis→cephalic shield→extension/contraction

-ciliated feeding tentacles

-u shaped digestive tract

-lacks dorsal nerve cord

-dioecious or monoecious

Deuterostomia 2

chordates

Phylum Chordata

-73,976 spp.

-5 Hallmarks

1. Notochord with myomeres

2. Dorsal hollow nerve cord

3. Pharyngeal gill slits

4. Endostyle

5. Postanal tail

Subphylum Cephalochordata:Class Cephalochordata

-lancelets amphioxus

-30 marine spp.

-5 hallmarks all readily apparent

-myomeres

-hepatic cecum- unique cellular ingestion/intracellular digestion

-no real brain on dorsal nerve cord

-no heart but ventral aorta pumps blood forward

-dioecious

-external fertilization and larval stage

Subphylum Urochordata

-tunicates

-3131 marine spp.

-most sessile filter feeders as adults, after swimming larva→some do not metamorphose and some are not sessile

-cellulose-like tunicin in tunic

-most spp. have 5 chordate hallmarks as larvae, retaining the gill slits, end-style, and a ganglionic vestige of the nerve cord as adults; losing tail and notochord completely

Class Ascidiacea

-ascidians or sea squirts

-2985 spp.

-95% of tunicates

-solitary or colonial

-sessile with rooting stolons

-nonfeeding “tadpole” larva in most

-ciliated pharyngeal basket (buccal and atrial siphon)

-food trapped in mucus enters u shaped digestive tract

-heart reverses flow on a regular cycle

-asexual fission and budding

-moslty simultaneous hermaphrodites with external fertilization

Class Appendicularia

-larvaceans

-68 spp.

-moslty <1cm, transparent

-solitary swimmers

-neotony: retain “tadpole” larval body as adults except tail moves 90% ventrally

-adults show 5 hallmarks

-anus directly to outside

-prey as small as 1µm

-rapid replacement of the tunic can be multiple times a day

-protandrous hermaphrodites (M→F)

Class Thaliacea

-salps

-78 spp.

-solitary or colonial swimmers

-asexual reproduction via budding in many spp. forming long chains

-larva becomes adult that retains pharynx

-all protogynous, but 3 orders vary in reproductive mode

1. oviparous with larvae

2. aplecentally viviparous with direct development

3. placentally viviparous with asexual proliferation in chains

Subphylum Vertebrata

-vertebrates

-70,815 spp.

-dorsal hollow nerve cord & anterior brain

-notochord→replaced during embryology by bony discs of vertebrae in most

-pharyngeal gill slits→primarily respiration, feeding function in some, lost in terrestrial spp.

-endostyle→thyroid gland

-postanal tail with caudal vertebrae in most taxa→bony vestige in frogs, birds, large old world primates, etc

Class Myxini

-hagfishes/slime eels

-82 spp.

-marine

-no jaws, paired fins, scales, or vertebrae

-predators & scavengers

-”teeth” of keratin on tongue (snail-like radula)

-glands along sides secrete viscous slime

-5-16 pairs of gills

-light detecting eyespots

-ventral heart with atrium and ventricle leading forward to gills

-self knotting behavior

-dioecious with external fertilization

Class Petromyzontida

-lampreys

-47 spp.

-marine, freshwater, and anadromous spp.

-no jaws, paired fins, scales or vertebrae

-jawless parasites of fish or non feeding adults with vestigial digestive tracts (brook lampreys)

-7 pairs of gills

-ventral heart with atrium and ventricle leading forward to gills

-dioecious with external fertilization

-filter feeding ammocoete larva

→chemical larvicides in Great Lakes

Jawed Fishes

-jaws from gills

-bones that support jaws come from the first set & second set of gill supporting cartilage

-5 gills in jawed fishes

Placoid scales

-modified teeth

-found in sharks and cartilaginous fishes

Ganoid scales

-bony fishes

Ctenoid scales

-comb (bluegill, perch)

-teleost fishes

Cycloid scales

-teleost fishes

Heterocercal tail

Homocercal tail

Diphycercal tail

Class Chondrichthyes

-cartilaginous fishes

-1282 spp.

-skeleton of calcified cartilage

-not primitive→derived loss of replacement by bone

-small notochord and calcified cartilaginous vertebrae

-no swim bladder→derived loss

-claspers in males by pelvic fins & cloaca

-oviparous or aplecentally or placentally viviparous

Subclass Elasmobranchii

-sharks, rays, & skates

-937 mostly marine spp.

-some freshwater/estaurine spp.(6 sharks, 1 ray, & 18 skates)

-placoid scales

-multiple gill slits (typically 5 on each side)

-heterocercal tail

Superorder Selachii

-sharks

-537 spp.

-numerous replaceable sharp teeth

-oviparous or aplecentally viviparous

Superorder Batoidea

-skates and rays

-689 spp.

-greatly enlarged pectoral fins

-bottom feeders with ventral mouths & gill slits

-skates

1. bilobed pelvic fin

2. tail: no barb, 2 distal fins

3. small teeth

4. oviparous with “mermaids purse”

-rays

1. unloved pelvic fins

2. tail: venemous barb (stingrays); no fin or single at base

3. large plate-like teeth

4. matrotrophic live bearers

Subclass Holocephali

-chimeras/ratfishes/ghost sharks

-56 marine spp.

-no scales

-3 pairs of hard grinding plates on jaws rather than teeth

-single exit from gill chamber

-most have venomous spines in dorsal fins

-diphycercal tail

-oviparous

-eggs laid in “mermaids purse”

Osteichthyes

-bony fish & tetrapods

-paraphyletic former taxon

-paraphyletic because lobe finned bony fishes are closer relatives of tetrapods than they are of ray-finned fished

-cartilage-replacement bone

-bony operculum over gills (gill plate)

-swim bladder in most→buoyancy

-acts as lung in primitive spp.

Class Actinopterygii

-ray-finned fishes

-32,513 spp.

-bony rays support fins

-most with homocercal tail→basal forms heterocercal or diphycercal

-most with cycloid or ctenoid scales→basal forms ganoid

Subclass Cladistsa

-bichirs and reedfish

-14 freshwater spp.

-7-18 dorsal finlets on branched spine

-diphycercal tail

-ganoid scales

-lungs