Dolphin Diet

Methods of collecting food: Bottle-nose dolphins do not chew their food. Usually they swallow fish whole, head first, so the spines of the fish won't catch in their throats. They break larger fish by shaking them or rubbing them on the ocean floor. Hunting strategies are varied and diverse: Bottle-nose dolphins often cooperate when hunting and catching fish.
In open waters, a dolphin pod sometimes encircles a large school of fish and herds them into a small, dense mass, sometimes using their tail flukes to stun the fish. The dolphins take turns charging through the school to feed. Occasionally dolphins herd schools of fish against a sand bar or shoreline to trap them in shallow water where they are easy prey. Dolphins use their powerful tail flukes when hunting, by hitting a fleeing fish up into the air with their tail, stunning it, then scooping the fish up when it falls back into the water.
Food: Bottle-nose 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.
Water: 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.
(Wild Dolphins)