Phylum Chordata

Phylum Chordata

• Characteristics of all chordates Dorsal, hollow nerve cord Post-anal tail Gill pouches at some time in the live Notochord

• The most complex of the animals

• Most, but not all, have backbones

Characteristics

Notochord Longitudinal flexible rod of cartilage

located between gut and dorsal nerve cord Persists into adulthood in some chordates In many it is replaced by vertebral column Spongy material between vertebral bones

is remnant of notochord

Characteristics

Dorsal Hollow Nerve Cord In embryo, formed from a plate of dorsal

ectoderm that rolls up into a tube Located dorsal to notochord Unique due to its hollow structure Develops into chordate’s central nervous

system

Characteristics

Pharyngeal Gill Slits Openings of the upper digestive tube in chordates Pharynx is area just behind mouth During embryonic stage of chordates these slits

connect the outside to the pharynx Early chordates used them as devices for filter

feeding Evolved and became modified to function in gas

exchange

Characteristics

Post Anal Tail Most chordates have tail extending beyond

the anus Many aquatic species have tail equipped

with skeletal and muscular tissue for movement.

Taxonomy of Chordates

Taxonomy- the study of classification

Phylum Chordata• Subphylum Urochordata• Subphylum Cephalochordata• Subphylum Vertebrata

• Superclass Fishes• Class Agnatha• Class Chondrichthyes• Class Osteichthyes

• Class Amphibia• Class Reptilia• Class Aves• Class Mammalia

Subphylum Urochordata

Tunicate-sea squirt are most popular example for study

Larva has all four chordate characteristics Retain only gill slits in adult

•Most are marine•No backbone

Subphylum Cephalochordata

Small marine animals just a few cm. long Lancelets-blade shape All four chordate characteristics persist in adult No backbone

Subphylum Vertebrata

Additionally, they demonstrate Cephalization Vertebral column (backbone) as part of

endoskeleton Closed circulatory System

• Show all four chordate characteristics at some

time in their life.

Superclass Fish Characteristics-

Primitive No jaws Cartilaginous skeleton Scaleless skin Oral sucker in place of

jaws Predators and filter

feeders Anticoagulating saliva Fresh and salt water

Examples Lamprey hagfish

Class Agnatha

Class Chondrichthyes Cartilaginous skeleton Skin covered with

denticles, not scales Five to seven gill slits per

side No swim bladder Internal fertilization Spiral valve intestines Five to seven gill arches

•Examples:sharksrays

Class OsteichthyesBony Fish

Largest group of vertebrates

Calcified skeleton Great

maneuverability Swim bladder for

control of buoyancy

Class Amphibia

Eggs are hatched in water and lack shell. First part of life is water and then move to

land. Name means “two lives” Examples:

Frogs, toads Newts, salamanders, necturus Legless, burrowing amphibians

Class Reptilia First true “land

animal” Amniote egg with

shell Scaly skin too thick

for respiration Formerly 16 orders 4 orders remain

turtles, tortoises

alligators, crocodileslizards,

snakestuatara

Class Aves Warm blooded Keel shaped breast

bone in birds that fly Hollow bones Characterized by:

beaks, wings, feathers

Class Mammalia Mammary glands to feed young Hair Differentiated teeth Most give live birth Warm blooded Sub-cutaneous fat Most have larger brains than other

vertebrates of their size.

Monotreme Mammals

Only in Australia and New Guinea

Hair and mammary glands No nipples Reptilian egg Only examples:

platypus

echidna

Echidna

Marsupial Mammals

Embryos born early and complete development in pouch

Examples:

opossum

kangaroo

bandicoot

koala

Placental Mammals

Young develop in uterus Joined to mother by

placenta

Examples- Placental Mammals

Edentata- Toothless

•Lagomorpha

Insectivora

Chiroptera

Primate

Rodentia

Carnivora

Artiodactyla

Perissodactyla

Proboscidea

Sirenia

Cetacea