Chordates 1

Chordate TaxonomyChordates:

1. Single dorsal hollow nerve cord

2. Gill slits

3. Notochord

Jawless = class Agnatha i.e. lamprey

Cartilaginous fish= class Chondrichthyes i.e. sharks and rays

Bony fish = class Osteichthyes i.e. tuna and salmon

Vertebrates = invade land 350 million years ago, lose support of water, 2 pairs of limbs, tetrapods (four footed)

Amphibians = class Amphibia i.e. frogs, toads, and salamanders

Reptiles = class Reptilia i.e. turtles, snakes, iguanas,

Sea turtle = order Chelonia

Birds = class Aves i.e. gulls, pelicans, and penguins

Mammals = class Mammalia i.e. seals, sea otters, whales, and dolphins

Dolphin TaxonomyKingdom

Phylum

Class

Order

Family

Genus

Species

Anamalia

Chordata

Mammalia

Cetacea

Delphinidae

Torsiops

Truncatus

Common name: Bottlenose dolphin

Chordate NotesPhylum - Hemichordata: share developmental characteristics of chordates and echinoderms, some have larva similar to enchinoderms. They also share feature of chorodates like nerve cord, gill slits, notochord. (acorn worms are deposit feeders similar to sea cucumbers).

Phylum- Chordata: (some are invertebrates)

• nerve cord

• gill slits (during part of life)

• Notochord - flexible support which becomes the backbone in vertebrates

• ventral heart

• tail (embryo)

Most chordates notochord is surrounded or replaced by bones (vertebrate column). This separates vertebrates from invertebrates.

Protochordates (invertebrate chordates)

Subphylum- Urochordata (tunicates):

• Sea squirts - only sessile chordate- Look somewhat like sponge; are filter feeders, H2O in incurrent siphon expelled out excurrent siphon. When disturbed they expel H2O out both siphons

Urochordate Tunicates

Larvaceans and Salps related to tunicates are important zooplankton that catch food with mucus net

• Have chordate characteristics as larva.

Subphylum- Cephalochordata (lancelets):

No back bone but do have:

• Nerve cord

• Gill slits

• Notochord

Lancelets-

• Fish shaped filter feeder

• Only missing back bone from being vertebrate

• Uses gill slits to gather organic particles

Vertebrates (Subphylum- Vertebrata) Chordates with backbone:

Share 3 characteristics of all Chordata:

• Nerve cord

• Gill slits

•Notochord

•But vertebrates have a backbone or vertebral column or spine (hollow bones called vertebrae, enclose and protect nerve cord.) Vertebrates are bilaterally symmetrical with endoskeleton. About 550 mya.

Fishes:

Class- Agnatha (Jawless fish):

• Feed by rasping round mouth

• Draws blood from host

• Body is eel like

Examples: Lampreys, hagfishes or slime eels