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Guide
to the Vertebrates of South Africa & Southern Africa
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The Subphylum
Vertebrata (Vertebrates) is part of Phylum Chordata and is divided
into:
• Amphibians
• Birds
• Fish
• Mammals
• Reptiles
Subphylum Vertebrata
Vertebrates, which include fishes, reptiles, amphibians, birds, and
mammals, all share a vertebral column, or a chain of bony elements
(vertebrae) that run along the dorsal surface from head to tail and
form the main skeletal axis of the body. The vertebral column surrounds
and more or less replaces the notochord as the chief "stiffener"
of the body in locomotion. Some characteristics shared by most or
all vertebrates (in addition to those traits shared among all chordates)
include the following (after Hickman, 1994):
-
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)
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movements
provided by muscles attached to endoskeleton
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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
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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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