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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.
The degree of calcification varies between species, with the sei whale having 14.5% hydroxyapatite, a mineral that coats teeth and bones, whereas minke whales have 1–4% hydroxyapatite. In most mammals, keratin structures, such as wool , air-dry, but aquatic whales rely on calcium salts to form on the plates to stiffen them. [ 58 ]
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.
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.
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 ]
[3] [4] Parts recovered include the jaw, front and hind legs, bits of spine, and tail. Olivier Lambert, a scientist at the Royal Belgian Institute of Natural Sciences and lead author of the study, noted that Peregocetus "fills in a crucial [knowledge] gap" about the evolution of whales and their spread.
For long-finned pilot whales, gestation lasts 12–16 months, and short-finned pilot whales have a 15-month gestation period. [3] The calf nurses for 36–42 months, allowing for extensive mother-calf bonds. [3] Young pilot whales will take milk until as old as 13–15 years of age.
Two stranded adult male strap-toothed beaked whales were recorded as only being able to open their mouths 3.2 cm and 4 cm wide, compared to females and juveniles that had a gape size of 6.5 cm. [7] It is thought male beaked whales use their teeth to compete for mating access to females, as evidenced by scars and scratches on the bodies of males ...