Module 2 - Taxonomy Flashcards
Pharungeal Gill Slits
Lost in living echinoderms, covered in most fish, highly adapted in tetrapods
Notochord (Chordata)
- fibrous, fluid-filled sheath
- Provides strength for swimming
- Hydrostatic skeleton - water incompressible
Postnatal tail - Chordata
Paddle
Dorsal Hollow Nerve Cord (DHNC)
Vs. ventral solid nerve cord
Endostyle (thyroid) - Chordata
Metabolic control
Cephalochordata
myomeres
muscle bands
myosepta
connective tissue between muscles
Cephalochordata
- amphioxus or lancet
- myomeres
- myosepta
- ^ both shared with vertebrates lost in urochordates
- largely sessile
- filter - feeder
- semitropical
Urochordata
Asicidiacea
Urochordata Asicidiacea
- no DHNC, notochord or postnatal tail as adults
- Ascidian tadpole - larva with all present
- Metamorphosis - absorb tail, notochord, and DHNC
Ascidian tadpole
larva with all present
metaporphosis
absorb tail, notochord, and DHNC
Early Vertebrates
- Agnatha (w/o jaws) - Paraphyletic
- Probable from something like Haikouella 530MYA
- 3cm long
- Had brain, but no skull
- Haikouchthys - had skull (craniata)
Haikouichthys
Craniata
- having bone or cartilage that forms at least a shelf for the brain
cyclostomata
Living Jawless craniates
- Myxini
- Pteromyzontiformes
Myxini - Hagfishes
Petromyzontida - Lampreys
condota
Pteraspidomorphi - Ostracoderms (bony plated skin)
Osteostraci - ostracoderms
Gnathostomata
Gnathostomata characteristics
Jaws - allowed access ot larger and more varied prey
- evolved from gill arches
paired fins
- allowed greater stability and ability to use water
- better development than in osteostracans