E ven though they live in the ocean all of the time, dolphins are mammals, not fish. Also, dolphins are different than "dolphinfish," which are also known as mahi-mahi. Like every mammal, dolphins are warm blooded. Unlike fish, who breathe through gills, dolphins breathe air using lungs. Dolphins must make frequent trips to the surface of the water to catch a breath. The blowhole on top of a dolphin's head acts as a "nose," making it easy for the dolphin to surface for air. Other characteristics of dolphins that make them mammals rather than fish are that they give birth to live young rather than laying eggs and they feed their young with milk. Also, like all mammals, dolphins even have a tiny amount of hair, right around the blowhole. Whales and porpoises are also mammals. There are 75 species of dolphins, whales, and porpoises living in the ocean.
Behavior and reproduction
All rights reserved. Most dolphins are marine and live in the ocean or brackish waters along coastlines. There are a few species, however, like the South Asian river dolphin and the Amazon river dolphin, or boto , that live in freshwater streams and rivers. The largest dolphin, the orca , can grow to be over 30 feet long. The smallest, the Maui dolphin, is just five feet long. Dolphins feed chiefly on fish and squid, which they track using echolocation, a built-in sonar that bounces sound waves off prey and reveals information like its location, size, and shape.
Dolphins are highly intelligent marine mammals and are part of the family of toothed whales that includes orcas and pilot whales. They are found worldwide, mostly in shallow seas of the continental shelves, and are carnivores, mostly eating fish and squid. Dolphin coloration varies, but they are generally gray in color with darker backs than the rest of their bodies. As climate change causes the seas and oceans to warm, dolphins are being seen more frequently in colder waters outside their historic ranges. Scientists are concerned that dolphins will have difficulty adapting as quickly as necessary to find new feeding grounds to sustain their populations. Some dolphins that live in areas where rivers and oceans meet, known as brackish waters, are also losing habitat as ocean levels rise due to global warming. Defenders fights any attempt to weaken the Marine Mammal Protection Act and all the protections it affords marine mammals like dolphins. We are currently litigating to challenge seismic blasting in the Atlantic Ocean that risks harming and killing thousands of dolphins. We are also opposing offshore oil and gas development in the Arctic and Atlantic, and working to promote wildlife- and whale-friendly best management practices for offshore wind siting and development.
Dolphin is a common name of aquatic mammals within the infraorder Cetacea. The term dolphin usually refers to the extant families Delphinidae the oceanic dolphins , Platanistidae the Indian river dolphins , Iniidae the New World river dolphins , and Pontoporiidae the brackish dolphins , and the extinct Lipotidae baiji or Chinese river dolphin. There are 40 extant species named as dolphins.