Post on 23-Feb-2016
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I NVERT EBRATE CH ORDAT ES ( NO BACK BONES) VERTEBRATE C H ORDAT ES
(H AVE BACK BONES )
PHYLUM CHORDATA
ALL CHORDATES HAVE THE FOLLOWING:• Notochord:• Flexible dorsal supporting rod• Usually replaced by a backbone as embryo
develops• Hollow dorsal nerve cord• As opposed to the ventral nerve in other
animals• Pharyngeal (throat) slits• In aquatic chordates, these gills are slits• In terrestrial chordates, these slits
disappear early in embryonic development
INVERTEBRATE CHORDATES
• Tunicates and lancelets•Not many of these but they are of great evolutionary interest• Possible link between vertebrates and all other animals
VERTEBRATE CHORDATES
• Fish (3 classes)• Amphibians• Reptiles• Birds•Mammals
VERTEBRATES (SUBPHYLUM VERTEBRATA)
• Characteristics:• Endoskeleton• Vertebral column (“backbone”)• Closed circulatory system• Ventral heart•Usually four appendages
TEMPERATURE CONTROL• All vertebrates must keep their body
temperatures within a certain range. There are 2 ways of doing this• Ectotherms: change behavior in response to
temperature fluctuations• Lack effective insulation, have low metabolic
rates, are fish, amphibians, reptiles• Endotherms: rely on heat generated by their
bodies (and some behavioral strategies)• They have insulation, high metabolic rates,
birds, mammals and possible dinosaurs
FISH
•Aquatic vertebrates with scales, fins and pharyngeal gills•Classes:• Agnatha: primitive jawless fish that are parasitic
or scavegers, includes lampreys and hagfish• Chondricthyes: ancient group of mostly
predatory cartilaginous fish (skeleton entirely cartilage), includes sharks, skates and rays• Osteichthyes: “regular” fish with a bony
skeleton. 97% of all fish are in this class