Animal Diversity Lecture 7

Notochord

Cartilage

Dorsal, Hollow Nerve Cord

Spinal cord in humans

Lancelets or Amphioxus

Cephalochordata

Marine, ~25 species

Cephalochordata

Inhabit shallow coastal waters

Cephalochordata

Tunicates or Sea Squirts

Urochordata or Tunicata

Marine, ~3,000 species

Urochordata

Hagfish

Myxini

Marine, bottom-dwelling scavengers

Myxini

Cartilagenous skull

Myxini

Lack Jaws

Myxini

Single eye and nasal opening

Myxini

Keratin based teeth

Myxini

Lamprey

Petromyzontida

Freshwater and marine

Petromyzontida

Jawless

Petromyzontida

Larvae also known as ammocoetes larva

Petromyzontida

Benthic filter feeders, similar to lancelets

Petromyzontida

Adults are giant fish ectoparasites

Petromyzontida

Use rasping tongue to penetrate skin

Petromyzontida

Gnanthostomes have

jaws, mineralized skeleton, appendicular skeleton

ancestral pharyngeal gill arches form upper and lower jaws

Evolution of Jaws

Mammalia, Reptilia

Amniotes

Amphibia

Tetrapods

Dipnoi, Actinistia

Lobe-fins

Actinopterygii

Osteichthyans

Chondrichthyes

Gnathostomes

Petromyzontida, Myxini

Vertebrates/Craniates

Urochordata, Cephalochordata

Chordates