Streamlined shape of body helps fish to

Thick layer of fat that keeps whales and dolphins warm inside water

Ducks have toes joined by thin layer of skin, this is called

Fins of fish help it to

Swim bladder helps fish to

Ducks have hollow bones and waterproof feathers

Dolphins have gills and blowholes to breathe

Gills are respiratory organs that help fish to absorb oxygen dissolved in water