Kingdom Animalia pt 2 Vertebrates Phylum Chordata All
Kingdom Animalia pt. 2 (Vertebrates)
Phylum Chordata All chordates have these characteristics at some time in their life: • Dorsal hollow nerve cord. • A notochord. • Paired gill slits or openings. • Post-anal tail.
Subphylum: Vertebrata • Notochord becomes reinforced with bone surrounded by the spinal column. • Dorsal nerve cord grows more complex with a brain and a protective skull. • The verebrata subphylum is divided into 7 classes of vertebrates: vertebrates jawless fish, cartilaginous fish, bony fish, amphibians, reptiles, birds, and mammals.
Class Agnatha (Jawless fish) • Slender, eel-shaped body with no jaws. • 7 external gill openings. • Notochord persists in the adult. • Skeleton of cartilage. • No paired fins. • No stomach.
Class Chondrichthyes (Cartilaginous Fish) • well-developed fins and teeth • 2 pairs of fins, one supported by pectoral girdle, other by pelvic girdle. • entire skeleton, including skull, without any true bone, though partly calcified, especially in vertebrae • Fertilization is internal
Class Osteichthyes (Bony Fish) • bony skeleton and fins, external fertilization • most diverse class of vertebrates. They comprise more than 95% of all fish and 50% of all species of vertebrates. • 2 chambered heart. Ectothermic -can’t regulate temp. • operculum (a flap on each side of the head that covers the gills). The movements of these flaps allow the fish to breathe without moving. • Most are carnivorous, some herbivores or detritivores
Tetrapods • emergence from water onto land subsequent diversification into amphibian and reptiles. • This transition from fish to tetrapod is poorly represented in the fossil record
Fossil from Carboniferous period (>300 mya)
Amphibians • bony skeleton with 4 legsadapted to moving on land • but have permeable skin • Three-chambered heart with two atria and one ventricle • unable to regulate body temperature • have aquatic eggs w/ external fertilization. • metamorphosis (Amphibia refers to "double life", or life in water and on land )
Amniotic Egg Huge adaptation in evolution of vertebrates: Waterproof egg with a shell can be deposited on land. Named for the membrane which surrounds the embryo.
Class Reptilia • better adapted to land: waterproof skin & scales • paired limbs with 5 toes • lungs for respiration, 3 chambered heart (except crocs). • internal fertilization & amniotic eggs. – eggs are covered with a leathery or calcium-based shell (lost in species that give birth to live young)
Crocodilians • Have 4 chambered heart • Most closely related to dinosaurs • Highly developed brain, complex social behaviors & parental care
Class Aves • Evolved from reptiles (should be called reptiles!) – 4 chambered heart • Feathers – modified scales (found in fossil dinosaurs) • Tetrapods -forelimbs are modified into wings. • Toothless & hollow bones (flight adaptations). • Crop & Gizzard- for grinding food (crocs have) • Branching air sacs in addition to lungs, helps increase air flow (adaptation to high energy needs)
Class Mammalia • Evolved from reptiles during age of dinosaurs. • Endothermic (regulate body temp) • All have hair and make milk. • 4 -chambered heart, 2 separate circulations. • All breathe with lungs (even aquatic species), and use muscular diaphragm to pull air in. • Internal fertilization w/ 3 types of development: • Monotremes – egg-layers • Marsupials – premature young, pouch • Placentals – embryo develops completely inside
Monotremes
Marsupials
Placental Mammals
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