Amphibian Notes Class Amphibia General Characteristics Amphibia means
Amphibian Notes (Class Amphibia)
General Characteristics Amphibia means Double life • Eggs are aquatic • Usually webbed feet • Smooth skin, moist with many glands, some poisonous glands, no scales • Respiration by lungs, skin and gills • Larvae have external gills (almost all) • 3 chambered heart (2 atria & 1 ventricle) • Double circulation • One supplied heart from lungs • One supplies body • METABOLISM - ectothermal – body temperature dictated by the environment (coldblooded) - a. k. a. Poikilotherms (changing temperature) • Fertilization internal in salamanders, but external in frogs • METAMORPHOSIS USUALLY PRESENT (ex. tadpole frog)
Three Orders of Amphibian s 1. Apoda = “no feet/legs” • Commonly called CAECILIANS • Long, limbless, burrowers, usually blind • About 160 species (S. America, Africa, SE Asia)
2. Caudata= have a tail • Tailed salamanders (~360 species) • 4 limbs, usually at right angles to the body • Limbs usually same size • Carnivores with low metabolism • Gills as larvae, most have lungs as adults • Some never go through metamorphosis (ex. mud puppy)
3. Anura= without a tail • Frogs and toads (~3450 species) • Head and trunk fused • Large mouth • Lungs (gills as larvae) • Color vision • Go through metamorphosis
Frogs vs. Toads Frog • Thinner • Longer legs – leapers! • More webbed feet • Smooth or slimy skin • Prefer moist environments • Lay eggs in clumps • Poison through skin Toad • Stout bodies • Short legs – not as good leapers • Thicker skin that is dry with warts • More terrestrial • Lay eggs in chains • Poison in two glands on back of neck (parotoid gland)
Three Types of Births in All Animals 1. Oviparous • Lay eggs (soft or hard shelled) • May or may not protect unhatched eggs • Common in most invertebrates and many vertebrates (reptiles, fish, birds, amphibians) 2. Ovoviviparous • Hold eggs inside, embryos derive all nourishment from egg yolk • Hatch internally or immediately after being released from female • Some invertebrates, few fish and reptiles (some 3. Viviparous snakes) • Eggs develop internally (uterus or oviduct) and receive nourishment directly from the mother • Mostly mammals, some sharks, amphibians & reptiles
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