What is the difference between dolphin and fish

Both dolphins and fish have adapted to live their whole lives in the water, both have streamlined bodies and fins. But, dolphins are mammals and so they need regularly visit the surface to breathe air to survive, otherwise they would drown. Fish on the other hand extract oxygen from the water and do not need to surface.

Dolphins evolved from land mammals whose legs were underneath their bodies. Dolphins are warm-blooded and have blubber to keep them warm.

Fish are cold-blooded and are able to adjust to the different temperatures of the water without the need of body fat to keep them warm. Most species of fish are also known to lay eggs and can lay hundreds of eggs in a single year. Dolphins give birth to a single baby once every 1 — 6 years and then feed their babies milk through their nipples. Females spawn, or lay eggs, several times per year. Larvae are tiny when they hatch, only about one-eighth of an inch long.

They quadruple in size in the first two weeks of life and grow about 5 inches per month. Both dolphins and dolphinfish are effective predators, but they prey on different kinds of organisms. Bottlenose dolphins hunt for fish, squids and shellfish such as crabs and shrimp.

They often work together to herd their prey into one location. Dolphins also can produce high-frequency sounds to find prey by echolocation. Dolphinfish feed mainly smaller fish, such as trigger fish and puffer fish.

They also prey on juveniles of larger fish such as tuna and mackerel. Dolphinfish rely on their keen eyesight and lateral line sensory system to find prey. She worked as a researcher and analyst in the biotech industry and a science editor for an educational publishing company prior to her career as a freelance writer and editor. Alissa enjoys writing about life science and medical topics, as well as science activities for children.

Three Adaptations for a Dolphin. Life Cycle of a Manatee. The Life Cycle of Bottlenose Dolphins. How Do Dolphins Mate? Although "dolphin" and "porpoise" are often used interchangeably, the term porpoise should refer only to the Phocoenidae family, in which there are seven porpoise species. The primary differences between dolphins and porpoises are anatomical. Externally, one can tell the difference between the two animals by looking at the head and dorsal fins.

Up close, one can distinguish the two by their teeth: dolphins have cone-shaped teeth, but porpoises have flat or spade-shaped teeth. Dolphins and porpoises vary in size, with dolphins generally being the larger of the two animals. The orca, or killer "whale," which is actually a dolphin, genetically , can be up to 35 feet long, for example, and the Hector's dolphin of New Zealand is sometimes smaller than 4 feet. On average, porpoises, which are more darkly-colored than dolphins, are between 5 and 8 feet long.

Both species breathe air from blowholes at the top of their head. And, like almost all mammals, they give live birth to their young and nurse their offspring. Dolphins and porpoises even have hair, but nearly all of it is lost shortly after birth. Of the three types of fins found on dolphins and porpoises, only the pectoral fins flippers , which are used for stopping and steering underwater, contain bones.

These fins actually contain the same number of bones as a human arm and end in five digits that are structured similarly to fingers.

Scientists theorize that these bones come from dolphins' and porpoises' land-dwelling ancestors some 50 million years ago. Beyond the pectoral fins, the dorsal, or back, fin provides stability as the dolphin and porpoise move quickly through water up to 25 mph. This dorsal fin, along with the tail flukes, is made of collagen, a fibrous connective tissue similar to cartilage. Both dolphins and porpoises use echolocation for navigating underwater, finding food, avoiding predators, and communicating with other members of their species.

The small external ear opening is about two inches behind the eye in both animals. Neither dolphins nor porpoises rely much on their sense of smell. Vocalizations are more extensive and frequent with dolphins, and can travel longer distances than those recorded for porpoises.