When considering the feeding habits and diet of whales, it is essential to differentiate between toothed whales and baleen whales.
Toothed Whales (Odontoceti)
Toothed whales, as their name implies, have teeth, which are instrumental in their hunting, catching and tearing at prey. In fact, these are the primary characteristic setting toothed whales apart from other whale species. They are active hunters; adept and finding and capturing prey. Although their diet depends on their own size as well as on their habitat, it can broadly be characterised as comprising of fish, marine mammals (such as seals, dolphins and even other whales) and squid. When available, they will also grab birds from the surface of the water.
Humpbacked Whale feeding.
In order to find prey, many toothed whales use echolocation. This involves the whale’s emitting a series of clicks from the front of their heads. These clicks come into contact with the prey (and whatever else is in the path of the animal), bounce off it and echo back to the whale. This is such a precise method that it communicates a wealth of information back to the whale; including the distance, shape, size, movement and even texture of the object perceived.
Humpback Whales are known for using an ingenious method to gather their prey. Some of the whales in the pod will swim around the school of fish, blowing bubbles to form a sort of wall around the fish so that they are trapped. The rest of the whales will make loud noises, scaring the fish and causing them to move to the water’s surface. As soon as the fish move upward, confused and panicked, the whales lurch into the school with their mouths wide open, capturing as many hapless victims as they can. Not all whale species cooperate to this degree, making the Humpback Whale a particularly fascinating one to study.
Baleen Whales (Mysticeti)
Baleen whales, on the other hand, feed by sucking large quantities of the sea water into their mouths through massive plates, effectively sieving out and consuming the tiny krill and other small crustaceans that are caught therein. This baleen plate resembles a hairy broom. The shape of the whale’s head and the size of its plates will determine just how much the animal is able to consume. Large baleen whales may consume about four percent of their body weight in krill every day. For the mammoth Blue Whale, this means consuming up to 3 600 kilograms, or 8 000 pounds.
Baleen whales are larger than toothed whales, despite feeding on significantly smaller prey.
The exception to the species is the Gray Whale, which is known to eat from the ocean floor. This species rolls onto its side, which disturbs the sand and causes it to rise, with whatever was hiding inside it. Therefore, this whale is less discerning about its diet, eating anything that it encounters in this way - from larvae to crustaceans to fish.
Whatever food is ingested that is more than what is required to fill the animal’s stomach is stored as blubber. This is a vital part of the whale’s survival as it helps to regulate body temperature and acts as a source of energy when the animal is migrating, breeding or in an area of limited food supplies.