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Pakicetids have long thin legs, with relatively short hands and feet which suggest that they were poor swimmers. [1] To compensate for that, their bones are unusually thick (osteosclerotic), which is probably an adaptation to make the animal heavier to counteract the buoyancy of the water. [7]
Female beaked whales' teeth are hidden in the gums and are not visible, and most male beaked whales have only two short tusks. Narwhals have vestigial teeth other than their tusk, which is present on males and 15% of females and has millions of nerves to sense water temperature, pressure and salinity.
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 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 dorsal end of the ribs are remarkably thin and almost fail to make contact with the transverse processes. The reduced tail (or sacrocaudal region) features a vestigial pelvis and small chevron bones. [18] The flippers have four digits. The lungs and heart are relatively small, which suggests that the pygmy right whale is not a deep diver.
Scientists think they might have finally learned the secret to how whales sing their complicated songs. We knew whales made a vast array of vocalizations, called songs, that can carry for ...
Based on the sizes of specimens, and to a lesser extent on composite skeletons, species of Pakicetus are thought to have been 1 metre (3 ft 3 in) to 2 metres (6 ft 7 in) in length. [4] Pakicetus looked very different from modern cetaceans, and its body shape more resembled those of land-dwelling hoofed mammals. Unlike all later cetaceans, it ...