(fish) phylum chordata Flashcards
how did non-vertebrate chordates?
post-anal tail fin
notochord from tip to tail
- contained elastic collagen rod runs all the way through
how has muscle in the fish changed?
went from V-shaped myomeres to W-shaped myomeres
where is the nerve chord in the lancelet?
slightly above the head
what fins did early Cambrian chordates have?
dorsal and ventral
early fish contained what type of bone?
dermal bone- forms in the skin - causing exoskeleton
primitive fish only had cartilaginous endoskeleton
what are the characteristics of jawless fish with dermal bone?
dermal bone coverings: carapace or scales
small mouths, jawless
late Devonian extinctions
in early phylum Chordata, where do the jaws start?
jaws from the anterior gill arches
which fish had bony exoskeletons?
jawless and jawed fish
what are the 2 living jawless orders?
hagfish orders
lamprey order
