Subphylum Vertebrata

Subphylum Vertebrata - skull, the most anterior component...

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Subphylum Vertebrata The subphylum Vertebrata consists of about 43,700 species of animals with backbones. Vertebrates exhibit all three of the chordate characteristics at some point during their lives. The embryonic notochord is replaced by a vertebral column in the adult. The vertebral column is made of individual hard segments ( vertebrae ) surrounding the dorsal hollow nerve cord. The nerve cord is the one chordate feature present in the adult phase of all vertebrates. The vertebral column, part of a flexible but strong endoskeleton , is evidence that vertebrates are segmented. The vertebrate skeleton is living tissue (either cartilage or bone) that grows as the animal grows. The endoskeleton and muscles form an organ system (the musculoskeletal system) that permits rapid and efficient movement. The pectoral and pelvic fins of fishes evolved into jointed appendages that allowed vertebrates to move onto land. The
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Unformatted text preview: skull, the most anterior component of the main axis of the vertebrate endoskeleton, encases the brain . The high degree of cephalization in vertebrates is accompanied by complex sense organs concentrated in the head region. Eyes developed as outgrowths of the brain. Ears were equilibrium devices in aquatic vertebrates that function as sound-wave receivers in land vertebrates. Vertebrates have a complete digestive system and a large coelom. Their circulatory system is closed, with respiratory pigments contained within blood vessels. Gas exchange is efficiently accomplished by gills, lungs, and in a few cases, moist skin. Kidneys are efficient in excretion of nitrogenous waste and regulation of water. Reproduction is usually sexual with separate sexes....
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