Bottlenose dolphins are active predators and feed on live
food, except when trained otherwise in captivity. They primarily
eat makerel, herring, cod, squids, sardines, cuttlefish and
shrimps. The foods available to a dolphin vary with its geographic
location. Adult bottle-nose dolphins eat approximately 4 to
5 percent of their body weight in food per day. A nursing
mother's intake is considerably higher: about 8 percent. A
dolphin's stomach is mpartmentalized for rapid digestion.
It can also function as a crop when food is taken opportunistically.
The amount of fish they eat depends on the fish species they
are feeding on: mackerel and herring have a very high fat
content and consequently have a high caloric value, whereas
squid has a very low caloric value, so to get the same energy
intake (calories) they will need to eat much more if they
feed on squid than if they feed on mackerel or herring. A
strong sphincter muscle in the throat enables dolphins to
swallow their food without ingesting too much seawater. Their
teeth are interlocking rows of conical pegs, suitable for
holding slippery fish. They eat their fish whole, headfirst.
Most dolphins live in the ocean and the ocean water is too
salty for them to drink. If they would drink seawater, they
would actually use more water trying to get rid of the salt
than they drank in the first place. Most of their water they
get from their food (fish and squid). Also, when they metabolize
(burn) their fat, water is released in the process. Their
kidneys are also adapted to retaining as much water as possible.
Although they live in water, they have live as desert animals,
since they have no direct source of drinkable water.