A similar program was used by the Russian Navy during the Cold War, in which belugas were also trained for antimining operations in the Arctic. a] The blue whale's long and slender body can be of various shades of greyish-blue dorsally and somewhat lighter underneath. Some studies have estimated that certain shastasaurid ichthyosaurs and the ancient whale Perucetus could have rivalled the blue whale in size, with Perucetus also being heavier than the blue whale with a mean weight of 180 tons; however, these estimates are based on fragmentary remains, as well as being subject to change as the latter was a very recently-described species. While pursuing krill patches, blue whales maximize their calorie intake by increasing the number of lunges while selecting the thickest patches.

Satellite-monitored movements of humpback whales Megaptera novaeanglia in the Southwest Atlantic Ocean". The responses also depended on the animal's behavioral state, its (horizontal) distance from the sound source and the availability of prey. A case study of a near vessel strike of a blue whale: perceptual cues and fine-scale aspects of behavioral avoidance". He asked for more bones, and Creagh soon sent parts of the skull, jaws, limbs, ribs, and backbone of the enigmatic creature. Because their heads are enormous—making up as much as 40% of their total body mass—and they have throat pleats that enable them to expand their mouths, they are able to take huge quantities of water into their mouth at a time.Sperm whales consist the largest and smallest odontocetes, and spend a large portion of their life hunting squid. In 1955 they were given complete protection in the North Atlantic under the International Convention for the Regulation of Whaling; this protection was extended to the Antarctic in 1965 and the North Pacific in 1966. Mysticetes include four extant (living) families: Balaenopteridae (the rorquals), Balaenidae (right whales), Cetotheriidae (the pygmy right whale), and Eschrichtiidae (the grey whale).

Odontocetes, as a whole, mostly feed on fish and cephalopods, and then followed by crustaceans and bivalves. The bones were so numerous that in some fields they were destroyed because they interfered with cultivating the land. In general, blue whale populations migrate between their summer feeding areas near the poles and their winter breeding grounds near the tropics. These pollutants can cause gastrointestinal cancers and greater vulnerability to infectious diseases.

One of the first published descriptions of a blue whale comes from Robert Sibbald's Phalainologia Nova, [8] after Sibbald found a stranded whale in the estuary of the Firth of Forth, Scotland, in 1692. This study also found significant gene flow between minke whales and the ancestors of the blue and sei whale. He had found vertebrae and other fragments while blasting on his property and also sent off a few samples to the Philadelphia society. A beaked whale for example has a small bulge sitting on top of its skull, whereas a sperm whale's head is filled up mainly with the melon. The story of Jonah being swallowed by a great fish is told both in the Qur'an [130] and in the biblical Book of Jonah (and is mentioned by Jesus in the New Testament: Matthew 12:40.

While nursing in the vertical position, a mother whale may sometimes rest with her tail flukes remaining stationary above the water.

The weight measured of the heart from a stranded North Atlantic blue whale was 180kg (400lb), the largest known in any animal. Other examples include the use of echolocation for hunting in low light conditions— which is the same hearing adaptation used by bats— and, in the rorqual whales, jaw adaptations, similar to those found in pelicans, that enable engulfment feeding. Petroglyphs off a cliff face in Bangudae, South Korea show 300 depictions of various animals, a third of which are whales. In the space of just three decades, a flood of new fossils has filled in the gaps in our knowledge to turn the origin of whales into one of the best-documented examples of large-scale evolutionary change in the fossil record.