Whales

Whales are known for their shear size, specifically the blue whale, becoming the largest animal on Earth growing to an average 82 feet and weighing a massive 300,000 pounds. Given their reputation for their size, one thinks that these large creatures must eat other large creatures to gain vast amounts of energy to keep up with their energy expenditure, however, it is quite the opposite. These large whales feed on krill, which are no more than 2 inches long. These large whales have evolved to have baleen, which are sheets of keratin which are used as a strainer. These whales suck in large portions of krill filled water into their oral cavity and use their tongue to push out all of the water, leaving the krill stuck in the baleen which they can then scoop and swallow. There are many hypothesis' on how baleen has come into play. Dental Filtration Hypothesis states that filter feeding evolved from dental cusps, similar to teeth with ripples, that would be used as a sort of strainer. Analogous to the crabeater seal. Medial Baleen Hypothesis states that the beginnings of baleen formed in middle of the mouth, going from the tip of the rostrum to the back, as opposed to on the dental row. Baleen would be more medial. Posterior Baleen Hypothesis states that the baleen formed towards the back of the mouth rather than starting at the tip of the rostrum. Suction Feeding Hypothesis states that they transitioned from a hunting style to a suction style feeding, gradually growing baleen to boost efficiency. However, it is still unclear which of these is the correct hypothesis as it is very difficult to gather information on these animals due to their large size, large range of habitat and their global protection.