Dolphins have no hind limbs, only ver small hip bones buried deep in the pelvic muscle and tissue. A dolphin breathes through a single blowhole , located on top of its head. A muscular flap covers the blowhole, making a watertight seal when dolphins dive. To take a breath, dolphins contract the muscular flap. When dolphins relax the muscles, the flap stays tightly closed.
Dolphins live in all oceans.
Dolphins live in all oceans of the world. While some inhabit one particular geographical area of an ocean, others like killer whales are found worldwide. Coastal, or inshore, dolphins live close to land and are often seen by people on beaches and boats. Oceanic, or offshore, dolphins live farther out at sea. Many dolphins have a homerange, an area where they tend to stay.