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Vertebrates include fish, amphibians, reptiles, birds, and mammals. All vertebrates shared one important vharacteristic,
which is a vertebrae. This is a long bony structure that runs down the back of a vertebrate. They also share all
of these characteristics:
- integument of two divisions, including an outer epidermis and an inner dermis; integument often modified to produce hair,
scales, feathers, glands, horn, etc.
- replacement of notochord by vertebral column more or less complete, depending on group
- bony or cartilaginous endoskeleton consisting of cranium, visceral arches, limb girdles, and 2 pairs of appendages
- muscular, perforated pharynx; this structure is the site of gills in fishes but is much reduced in adult land-dwelling
forms (although it is extremely important in embryonic development of all vertebrates)
- movements provided by muscles attached to endoskeleton
- digestive system with large digestive glands, liver, and pancreas
- ventral heart with 2-4 chambers
- blood with red blood corpuscles containing hemoglobin, and in addition, white corpuscles
- well developed body cavity (coelom) containing visceral systems
- paired kidneys with ducts to drain waste to exterior
- most vertebrates with two sexes, each with paired gonads (there are some exceptions)
- general body plan consisting of head, trunk, 2 pairs of appendages, and postanal tail (but these structures are highly
modified in many vertebrates and sometimes absent).
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