Chordates 1
Chordate Taxonomy
Chordates:
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 Taxonomy
Kingdom
Anamalia
Phylum
Chordata
Class
Mammalia
Order
Cetacea
Family
Delphinidae
Genus
Torsiops
Species
Truncatus
Common name: Bottlenose dolphin
Chordate Notes
Phylum - 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