2017-09-19 ZEN161 Prac 5 Content.pdf

2017-09-19 ZEN161 Prac 5 Content.pdf - PRACTICAL 5 Fish...

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1 PRACTICAL 5 Fish, Reptilia, Aves and Mammalia Phylum Chordata Chordates are deuterostome coelomates Four characteristics are present at some stage during development: Notochord Pharyngeal slits Tubular nerve cord Postanal tail Include animals like fishes, amphibians, reptiles, birds and mammals Subphylum Craniata Skull that surrounds the: Brain Olfactory organs Eyes Inner ear Infraphylum Vertebrata Vertebra present that surround the nerve cord and serve as primary axial support Superclass Gnathostomata Class Chondrichthyes Fishlike, jawed, paired appendages and cartilaginous skeleton No swimbladder Include skates, rays and sharks Subclass Elasmobranchii Cartilaginous endoskeleton Placoid scales No swim bladder to regulate buoyancy These animals need to swim continuously in order for water to move over the gills since they do not have opercula (singular: operculum) present that helps to “pump” water over the gills
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