Phylum Chordata

SubphylumUrochordata

SubphylumCephalochordata

SubphylumVertebrata

tunicates lancets AgnathansFishSharkstetrapods

Characteristics of Chordates

1st fish

Proto-vertebrate

Tunicate larvae Adult tunicate

lancelet

Possible evolution of 1st fish

PikaiaBurgess Shale FaunaCambrian540-500 mya

Early Chordate ancestor may have given rise to 1st vertebrate

General Features Shared by Chordates:

1. Eukaryote2. Multicellular3. Bilateral- deuterstomes4. Heterotrophic

Phylum Chordata Subphylum Urochordata - Tunicates

Class Ascidiacea - Sea SquirtsSolitary e.g. Styela montereyensisColonial - in groups but with own tunicCompound Colonial - colonial with sharedtunic

Class Thaliacea - Salps (free swimming),planktonic

Class Larvacea - Gelatinous house, planktonic

SubphylumUrochordataSubphylumUrochordata

tunicate

Subphylum Urochordata = tunicate

Tunicate - also called 'sea squirt' • notochord is confined to the tail • notochord is lost during

metamorphosis into sessile adult • possess pharyngeal slits • Repro- sexual (hermaphroditic)

& asexual (budding)

Tunicate Adult Anatomy

Tunicates:

Free swimming larva:• notochord present only in free-swimming  larvum• notochord does not extend into head• larvum is free-swimming but non-feeding• adult is sessile filter feeder

Settled larva:• Settle after brief free-swimming larvum existence.  • Attaches at anterior end.  • Metamorphosis begins.  • Body turns 1800.  • Tail, notochord, dorsal nerve cord, disappear.

Class Larvacea - planktonic

Oikopleura

Oikopleura

Jelly-like house

Marine snow

Class Larvacea - Gelatinous house, planktonic

Pyrosoma- bioluminescentColonial salp

Class Thaliacea - Salps (free swimming), planktonic

Class Ascidiacea - Sea Squirts

SubphylumCephalochordata

SubphylumCephalochordata

lancet

• Strictly marine• Live buried in sand with head sticking out• Filter feeders

Lancet Anatomy

Vertebrate Higher Classification Superclass Agnatha - without jaws

Class Myxini – hagfishes Class Cephalaspidomorphi – lampreys

Superclass Gnathostomata – with jaws Class Chondrichthyes – sharks, rays, chimaeras Class Actinopterygii – ray-finned fishes Class Sarcopterygii – lobe-fin fishes Class Amphibia – frogs, salamanders Class Reptilia – snakes, lizards, crocodiles Class Aves - birds Class Mammalia - mammals

Agnatha (jawless fishes)• Lack: paired fins, scales,

& well developed vertebrae

• Hagfish (slime eels)– Mucus for protection– Feed on decaying flesh

• Lampreys– Parasitic– Anadromous

• Marine adults, breed in freshwater

Class ChondrichthyesSharks, skates, rays,chimera

SubphylumVertebrata

• Heterocercal tail

• Two dorsal fins

• Paired pectorals

• 5-7 gill slits

• ureoosmotic

Chondrichthyes (cartilagenous fishes)

Osteichthyes (bony fishes)

• Swim bladder

• Operculum (gill cover)

• Homocercal tail

• Scales of bony origin– Smooth cycloid– Spiny ctenoid

Intestine

Adipose fin(characteristicof trout)

Cut edgeof operculum

Swimbladder Caudal

fin

Lateralline

UrinarybladderPelvic

fin

Anus

Dorsal finSpinal cord

Brain

Nostril

Gills

Kidney

Heart

Liver

Gonad

Anal fin

Stomach

Class AmphibiaClass Amphibia

Characteristics

• Cold blooded• Returns to water to breed• Metamorphosis• Some toxic• Estivation-dry and hot• Hibernation- cold

3,500 species

Class AmphibiaClass Amphibia

Rana cancrivora

salamander

Poison arrow frog

newt Mudpuppy (salamander)

Coqui

Class ReptiliaClass Reptilia

Characteristics

• Cold blooded• Have scales• Amniotic egg• Dry skin• 3 chambered heart (except crocks)

6,500 species

Class ReptiliaClass Reptilia

Sea snakeMarine turtle

Saltwater crocodile

Marine iguana

Class AvesClass Aves

Characteristics

• Warm blooded• Feathers and wings• Hollow bones• Horny bill• Lungs have air sacks• Hard egg shell

Class Aves

Class MammaliaClass Mammalia

Characteristics

• Warm blooded• Have fur or hair• Suckle young• 3 middle ear bones

Class MammaliaClass Mammalia

Subclasses• Protheria- echidna & platypus• Metatheria- marsupial• Eutheria- true mammals