Frogs, toads, basilisk lizards, and salamanders {amphibian} are cold-blooded.
skeleton: palate
Cartilage secondary palate allows breathing and eating at same time, by closing either nose or mouth.
skeleton: neck
Joint between head and trunk {neck, amphibian} allows head scanning and turning.
skeleton: pelvis
Amphibians have a pelvis, allowing hind limbs more mobility on land.
skin
Amphibians have vascularized smooth and moist skin, which can change color using pituitary intermedin hormone. Some amphibians secrete poison.
skin: claws
Claws allow better grasping by hands and feet, for better traction on land.
circulation
Four-chambered heart, divided into auricle and ventricle for pumping blood to lungs and auricle and ventricle for pumping blood to body, allows blood circulation through lungs and improved respiration.
lung
Amphibians have primitive lungs.
excretion
Amphibians have kidneys to regulate hydrogen and salt ion balance.
reproduction
Amphibians reproduce like fish.
senses: smell
Pharynx-top vomeronasal system is for olfaction, mainly for pheromones, and depends on different genes than olfactory bulb.
senses: vision
Thalamus and optic tectum evolved for vision, possibly localizing objects and detecting size.
nervous system
Amphibians can detect motion and location and use behaviors that require knowing trajectories and depth. They represent sensations in midbrain.
evolution
Amphibians evolved from Rhipidistian lobefin fish.
development
Like chordates, life stages are egg, larva, and adult. Egg and larval stages live in water. Adults stay on land. Eggs become tadpoles, which have gills, eat plants, and metamorphose to adults. Metamorphosis is under thyroid-gland control, releasing hormone after pituitary-gland signal.
regeneration
Salamanders can regenerate legs and tails.
Amphibians have soft palates {secondary palate}, allowing breathing and eating at same time by closing either nose or mouth.
Amphibians reproduce as fish do. Eggs become larvae {tadpole}|, which have gills, eat plants, and metamorphose to adults.
Toad or frog larvae {polliwog} initially have no legs, have gills, and live in water.
Mexican Ambystoma salamanders {axolotl} can retain gills and mature without metamorphosis.
Frogs {bull frog} can be large, with low croaks.
Amphibians {frog} can identify flies as small-size dark spots moving at rates. Frogs do not perform complex shape analysis [Lettvin et al., 1959]. Some tropical frogs have skin alkaloid poisons {pumiliotoxin}, such as PTX 251D.
small salamander {newt}.
small, lizard shape {salamander, amphibian}.
land, rough skin {toad}.
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Date Modified: 2022.0225