What are Marine Mammals?
| Cetacea | Pinnipedia | Sirenia |
Marine Mammals are a number of species of mammals divided into five groups that have partially or completely adapted to life in an aquatic environment. Despite the name they mainly, but not exclusively in saltwater. Unlike most animal groups, cetacea do not all share the same ancestry or lineage, but can be divided into the following orders: Cetacea (cetaceans), Pinnipedia (pinnipeds) and Sirenia (sea cows). Sea otters and polar bears are also included among the marine mammals, but they fall under their own order that does not exclusively consist of marine mammals.
The most numerous order and the main subject of this website are the 'Cetacea' or Cetaceans. This includes whales and dolphins aswell as porpoises. This group includes about 82 species of marine mammals that all live completely in the water. They are also the most adapted to aquatic life of all marine mammals. The most famous is the bottlenose dolphin, often followed by the orca or killer whale. All types of cetaceans are divided into two groups; The the "Mysticeti", or baleen whales and the "Odontoceti", or toothed whales.
The baleen whales are the largest and feed with horn-like plates with which they sift food out of the water (such as plankton or krill), the toothed whales have ivory teeth with which they catch prey and communicate. Cetaceans come in all shapes, colors and sizes. In general, they are quite large animals. Many cetaceans can be about ten to twenty meters long. However, there are also small cetacea of only one and a half meters long, such as the vaquita porpoise or the Hector's dolphin.
The largest animal on earth, and also the largest animal that ever lived, also belongs to the cetaceans. This is the blue whale. The largest blue whale ever documented was 33.85 meters long!