feed their young with milk

lay eggs

breathe with lungs

are warm-blooded

have a beak

are covered with scales

give birth to their young and feed them with milk

lay eggs with leathery shells

are covered with feathers

are warm-blooded

breathe with lungs

give birth to their young and feed them with milk

breathe with lungs

are covered with scales

have fins but no legs or toes

have a single pair of antennae on the head

give birth to their young and feed them with milk

often have wings and can fly

have three pairs of legs

have fins but no legs or toes

breathe with gills

have a single pair of antennae on the head

are warm-blooded

are covered with feathers

give birth to their young and feed them with milk

are covered with feathers

have three pairs of legs

have a beak

have fins

have four legs without claws or nails on toes

are warm-blooded

breathe with lungs, gills, and/or their skin

are covered with scales

lay eggs, usually in a jelly-like mass in water