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Sperm whales have the largest brain mass of any animal on Earth, averaging 8,000 cm 3 (490 in 3) and 7.8 kg (17 lb) in mature males. [28] The brain to body mass ratio in some odontocetes, such as belugas and narwhals, is second only to humans. [29] In some whales, however, it is less than half that of humans: 0.9% versus 2.1%. [citation needed]
However, pakicetids were able to listen underwater by using enhanced bone conduction, rather than depending on the tympanic membrane like other land mammals. This method of hearing did not give directional hearing underwater. [20] Pakicetids have long thin legs, with relatively short hands and feet which suggest that they were poor swimmers. [1]
Whales have two flippers on the front, and a tail fin. These flippers contain four digits. Although whales do not possess fully developed hind limbs, some, such as the sperm whale and bowhead whale, possess discrete rudimentary appendages, which may contain feet and digits.
Beaked whales have several anatomical adaptations to deep diving: large spleens, livers, and body shape. Most cetaceans have small spleens. However, beaked whales have much larger spleens than delphinids, and may have larger livers, as well. These anatomical traits, which are important for filtering blood, could be adaptations to deep diving.
The skim-feeders are right whales, gray whales, pygmy right whales, and sei whales (which also lunge feed). To feed, skim-feeders swim with an open mouth, filling it with water and prey. Prey must occur in sufficient numbers to trigger the whale's interest, be within a certain size range so that the baleen plates can filter it, and be slow ...
Whales and their relatives have a soft tissue flipper that encases most of the forelimb, and elongated digits with an increased number of phalanges. [9] Hyperphalangy is an increase in the number of phalanges beyond the plesiomorphic mammal condition of three phalanges-per-digit. [ 10 ]
Pitman, who has studied killer whales in Antarctica for over 10 years, said there's a similar divide between mammal- and fish-eating killer whales in those waters.
Then he advises what sort of Apes to make the choice of, as most resembling a Man : And conclude "One ought to know the Structure of all the Bones either in a Humane Body or in an Apes ; 'tis best in both ; and then to go to the Anatomy of the Muscles." [7] Up until that point, Galen and his teachings had been the authority on human anatomy ...