Phylum Chordata Bio ch 18 AMPHIBIANS Class Amphibia
Phylum Chordata Bio ch 18
AMPHIBIANS
Class Amphibia • • • Live part of lives on land part in water Aquatic ones – spend entire life in water Terrestrial – spend adult lives on land Referred to as tetrapods because most have four limbs Are subdivided into three categories: – Anura – Gymnophiona – Caudata
Anura • Frogs • Largest order • Will often live in or near water • Can also inhabit drier areas, but generally not the desert
Gymnophiona • Caeceilians • Legless, generally burrowing creatures • Resemble large earthworms, but have vertebrae, closed circulatory systems & jaws
Caudata • • Salamanders Hatch from eggs in water as larva Will breathe with gills and then go through metamorphosis Transition to terrestrial or semiaquatic lifestyle
Structure • Thin, moist, highly permeable skin • Most have lungs, but they are small • Closed circulatory system • Secrete mucus onto skin to keep moist while on land
Structure continued • Lack a diaphragm • Buccal pumping
Structure continued Three chambered heart 2 atria 1 ventricle They contract at different times so that blood does not mix • As blood circulates it picks up nitrogenous wastes and delivers to kidneys to be eliminated • •
Structure continued • Larvae are generally herbivores • Adults are generally carnivorous • They will eat anything that will fit in its mouth
• Both digestive and urogenital tracts end in cloaca • Nervous system can be subdivided • Are ectothermic: • Estivation • Hibernation Structure continued
Reproduction • • • Each species has its own mating call Amplexus External fertilization Salamanders = internal Incomplete metamorphosis Amount of parental care varies
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