The Earth's magnetic field is aligned with the north and south poles, and has reversed many times during geologic history. Sharks may use the magnetic field of the Earth for navigation purposes on migrations. It is the fastest swimming fish. Makos can maintain a body temperature higher than that of the surrounding water. Primitive mammals evolved during the Triassic period.
Whales are mammals.
These harmless rays have a short tail and no stinging spine. Mantas eat microscopic plankton, small fish, and tiny crustaceans. Mantas are common and are found worldwide in tropical seas, living both close to shore and in open seas. Whales, dolphins, seals, sea lions, and sea otters are marine mammals. Only fossilized teeth have been found.