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Baleen whales split from toothed whales (Odontoceti) around 34 million years ago. Baleen whales range in size from the 6 m (20 ft) and 3,000 kg (6,600 lb) pygmy right whale to the 31 m (102 ft) and 190 t (210 short tons) blue whale, the largest known animal to have ever existed. [1] [2] They are sexually dimorphic.
It is divided into toothed whales (Odontoceti) and baleen whales (Mysticeti), which diverged from each other in the Eocene some 50 million years ago (mya). Cetaceans are descended from land-dwelling hoofed mammals, and the now extinct archaeocetes represent the several transitional phases from terrestrial to completely aquatic. [1]
Unlike toothed whales, baleen whales do not have wax ester deposits nor branched fatty chain acids in their blubber. Thus, more recent evolution of these complex blubber traits occurred after baleen whales and toothed whales split, and only in the toothed whale lineage. [10] [11] [12]
That means baleen whales make their sounds with their larynx, as do humans, while toothed whales - including dolphins, porpoises, killer whales and s Scientists discover the anatomy behind the ...
The adaptation of animal echolocation in toothed whales distinguishes them from fully aquatic archaeocetes and early baleen whales. The presence of baleen in baleen whales occurred gradually, with earlier varieties having very little baleen, and their size is linked to baleen dependence (and subsequent increase in filter feeding).
Bowhead whale plates can be 9 metres (30 ft) long. Their nostril(s) make up the blowhole, with one in toothed whales and two in baleen whales. [21] The nostrils are located on top of the head above the eyes so that the rest of the body can remain submerged while surfacing for air. The back of the skull is significantly shortened and deformed.
An orca breaching in Hood Canal. The marine mammals of the Salish Sea are numerous and diverse, both in taxonomy and morphology. A total of six species of pinnipeds, eight species of baleen whales, seventeen species of toothed whales, and one mustelid (the sea otter) inhabiting the local waters of the Salish Sea and the outer coastal waters over the continental shelf off Washington and British ...
Since the 1800s, only six other spade-toothed whales have been documented. On July 4, a spade-toothed whale washed up near Taiari Mouth in New Zealand and is the first whole animal recovered in ...