Portal:Cetaceans
The Cetaceans Portal
Cetaceans (from Latin: cetus, lit. 'whale', from Ancient Greek: κῆτος, romanized: kētos, lit. 'huge fish', sea monster) are aquatic mammals constituting the infraorder Cetacea (/sɪˈteɪʃə/), including whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel themselves through the water with powerful up-and-down movement of their tail which ends in a paddle-like fluke, using their flipper-shaped forelimbs to maneuver.
While the majority of Cetaceans live in marine environments, a small number exclusively reside in brackish water or freshwater. Having a cosmopolitan distribution, they can be found in some rivers and all of earth's oceans and many species inhabit vast ranges where they migrate with the changing of the seasons.
Cetaceans are famous for their high intelligence and complex social behaviour as well as the enormous size of some of its members, like the blue whale reaching a maximum confirmed length of 29.9 meters (98 feet) and weight of 173 tonnes (190 short tons), making it the largest animal known to have ever existed.
There are approximately 86 living species split into two parvorders: Odontoceti or toothed whales (containing porpoises, dolphins, other predatory whales like the beluga and the sperm whale, and the poorly understood beaked whales) and the filter feeding Mysticeti or baleen whales (which includes species like the blue whale, the humpback whale and the bowhead whale). (Full article...)
Recognized content - 
Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. They are an informal grouping within the infraorder Cetacea, which usually excludes dolphins and porpoises. Whales, dolphins and porpoises belong to the order Cetartiodactyla, which consists of even-toed ungulates. Their closest non-cetacean living relatives are the hippopotamuses, from which they and other cetaceans diverged about 54 million years ago. The two parvorders of whales, baleen whales (Mysticeti) and toothed whales (Odontoceti), are thought to have had their last common ancestor around 34 million years ago. Whales consist of eight extant families: Balaenopteridae (the rorquals), Balaenidae (right whales), Cetotheriidae (the pygmy right whale), Eschrichtiidae (the grey whale), Monodontidae (belugas and narwhals), Physeteridae (the sperm whale), Kogiidae (the dwarf and pygmy sperm whale), and Ziphiidae (the beaked whales).
Whales are fully aquatic, open-ocean creatures: they can feed, mate, give birth, suckle and raise their young at sea. Whales range in size from the 2.6 metres (8.5 ft) and 135 kilograms (298 lb) dwarf sperm whale to the 29.9 metres (98 ft) and 190 metric tons (210 short tons) blue whale, which is the largest known creature that has ever lived. The sperm whale is the largest toothed predator on earth. Several whale species exhibit sexual dimorphism, in that the females are larger than males. (Full article...)
The fin whale (Balaenoptera physalus), also known as finback whale or common rorqual and formerly known as herring whale or razorback whale, is a cetacean belonging to the parvorder of baleen whales. It is the second-longest species of cetacean on Earth after the blue whale. The largest reportedly grow to 27.3 m (89.6 ft) long with a maximum confirmed length of 25.9 m (85 ft), a maximum recorded weight of nearly 74 tonnes (73 long tons; 82 short tons), and a maximum estimated weight of around 114 tonnes (112 long tons; 126 short tons). American naturalist Roy Chapman Andrews called the fin whale "the greyhound of the sea ... for its beautiful, slender body is built like a racing yacht and the animal can surpass the speed of the fastest ocean steamship."
The fin whale's body is long and slender, coloured brownish-grey with a paler underside. At least two recognized subspecies exist, in the North Atlantic and the Southern Hemisphere. It is found in all the major oceans, from polar to tropical waters. It is absent only from waters close to the pack ice at the poles and relatively small areas of water away from the open ocean. The highest population density occurs in temperate and cool waters. Its food consists of small schooling fish, squid, and crustaceans including copepods and krill. (Full article...)
Reconstructed skeleton at the Natural History Museum of the University of Pisa
Ambulocetus (Latin ambulare "to walk" + cetus "whale") is a genus of early amphibious cetacean from the Kuldana Formation in Pakistan, roughly 48 or 47 million years ago during the Early Eocene (Lutetian). It contains one species, Ambulocetus natans (Latin natans "swimming"). Ambulocetus is known primarily from a single skeleton which is about 80% complete, and is among the most completely known Eocene cetaceans, instrumental in the study of cetacean evolution and the transition from land to sea. It had four functional limbs, and was the first cetacean discovered preserving a suite of adaptations consistent with an amphibious lifestyle. Ambulocetus is classified in the group Archaeoceti—the ancient forerunners of modern cetaceans whose members span the transition from land to sea—and in the family Ambulocetidae, which includes Himalayacetus and Gandakasia (also from the Eocene of the Indian subcontinent).
Ambulocetus probably had a long, broad, and powerful snout, and eyes near the top of the head. Because of these features, it is hypothesised to have behaved much like a crocodile, waiting near the water's surface and ambushing large mammals, using the jaws to clamp onto and drown or thrash prey. The modern cetacean ear is highly specialised for hearing underwater and detecting certain frequencies, and Ambulocetus seems to share some of these traits. It is unclear if it used its specialised ear for hearing underwater, bone conduction on land, or if the adaptations were entirely non-functional in less aquatic cetaceans. Ambulocetus had a narrow, streamlined body, and heavy, pachyostotic ribs. It is thought to have swum much like a modern river otter, alternating beats of the hind limbs while keeping the forelimbs tucked in for most of its propulsive power, as well as undulating the torso and tail. On land, Ambulocetus may have walked much like a sea lion. It may have had webbed feet and lacked a tail fluke. (Full article...)
Pilot whales are cetaceans belonging to the genus Globicephala. The two extant species are the long-finned pilot whale (G. melas) and the short-finned pilot whale (G. macrorhynchus). The two are not readily distinguishable at sea, and analysis of the skulls is the best way to distinguish between the species. Between the two species, they range nearly worldwide, with long-finned pilot whales living in colder waters and short-finned pilot whales living in tropical and subtropical waters. Pilot whales are among the largest of the oceanic dolphins, exceeded in size only by the orca. They and other large members of the dolphin family are also known as blackfish.
Pilot whales feed primarily on squid, but will also hunt large demersal fish such as cod and turbot. They are highly social and may remain with their birth pod throughout their lifetime. Short-finned pilot whales are one of the few mammal species in which females go through menopause, and postreproductive females continue to contribute to their pod. Pilot whales are notorious for stranding themselves on beaches, but the reason behind this is not fully understood. The conservation status of short-finned and long-finned pilot whales has been determined to be least concern. (Full article...)
Whaling in the Faroe Islands, or grindadráp (from the Faroese terms grindhvalur, meaning pilot whale, and dráp, meaning killing), is a type of drive hunting that involves herding whales and dolphins into shallow bays to be beached, killed and butchered. The practice dates back to the 9th century and many Faroe Islanders consider eating whales to be an important part of their history.
The practice has been regulated by the Faroese authorities since 1948, and today involves modern boats and communications, trained participants and police supervision. Each year, around 700 long-finned pilot whales and several hundred Atlantic white-sided dolphins are caught during the summer season. The whale hunt has been subjected to increasing scrutiny since the 1980s, when concerns arose over the potential toxicity of whale meat. Animal rights groups have also labelled it cruel and unnecessary. (Full article...)
Bottlenose dolphin breaching in the wake of a boat
Bottlenose dolphins are aquatic mammals in the genus Tursiops. They are common, cosmopolitan members of the family Delphinidae, the family of oceanic dolphins. Molecular studies show the genus definitively contains two species: the common bottlenose dolphin (Tursiops truncatus) and the Indo-Pacific bottlenose dolphin (Tursiops aduncus). Others, like the Burrunan dolphin (Tursiops (aduncus) australis), may be alternately considered their own species or be subspecies of T. aduncus. Bottlenose dolphins inhabit warm and temperate seas worldwide, being found everywhere except for the Arctic and Antarctic Circle regions. Their name derives from the Latin tursio (dolphin) and truncatus for their characteristic truncated teeth.
Numerous investigations of bottlenose dolphin intelligence have been conducted, examining mimicry, use of artificial language, object categorization, and self-recognition. They can use tools (sponging; using marine sponges to forage for food sources they normally could not access) and transmit cultural knowledge from generation to generation, and their considerable intelligence has driven interaction with humans. Bottlenose dolphins gained popularity from aquarium shows and television programs such as Flipper. They have also been trained by militaries to locate sea mines or detect and mark enemy divers. In some areas, they cooperate with local fishermen by driving fish into their nets and eating the fish that escape. Some encounters with humans are harmful to the dolphins: People hunt them for food, and dolphins are killed inadvertently as a bycatch of tuna fishing and by getting caught in crab traps. (Full article...)
Zygophyseter varolai is an extinct sperm whale that lived during the Tortonian age of the Late Miocene 11.2 to 7.6 million years ago. It is known from a single specimen from the Pietra Leccese Formation in Italy. It was a member of a stem group of fossil macroraptorial sperm whales (often shortened to "raptorial") also including Brygmophyseter, Acrophyseter, and Livyatan. It probably grew to be around 6.5 to 7 meters (21 to 23 ft) in length and shared some characteristics with other raptorials, such as large teeth with tooth enamel that were functional in both the upper and lower jaws which the modern sperm whale (Physeter macrocephalus) lacks. It also had a beak, the ability to echolocate prey, and could have probably swum faster than the modern-day sperm whale which goes 4 kilometers per hour (2.5 mph). These were probably used in the capture of large prey, such as large fish, seals, and whales. In fact, its common name, the killer sperm whale, refers to its feeding habits that would have had a resemblance to the modern-day killer whale (Orcinus orca). (Full article...)
The false killer whale (Pseudorca crassidens) is a species of oceanic dolphin that is the only extant representative of the genus Pseudorca. It is found in oceans worldwide but mainly frequents tropical regions. It was first described in 1846 as a species of porpoise based on a skull, which was revised when the first carcasses were observed in 1861. The name "false killer whale" comes from the similar skull characteristics to the killer whale (Orcinus orca).
The false killer whale reaches a maximum length of 6 m (20 ft), though size can vary around the world. It is highly sociable, known to form pods of up to 50 members, and can also form pods with other dolphin species, such as the common bottlenose dolphin (Tursiops truncatus). Further, it can form close bonds with other species, as well as partake in sexual (including both heterosexual and homosexual) interactions with them. Conversely, the false killer whale has also been known to feed on other dolphins, though it typically eats squid and fish. It is a deep-diving dolphin, with a maximum recorded depth of 927.5 m (3,043 ft); its maximum speed is around 29 km/h (18 mph). (Full article...)
Brygmophyseter, known as the biting sperm whale, is an extinct genus of toothed whale in the sperm whale family with one species, B. shigensis. When it was first described in 1994, the species was placed in the genus Scaldicetus based on tooth morphology, but this was later revised in 1995. In 2006, it was classified into the genus Naganocetus, which is considered to be a junior synonym. The only known specimen, a nearly complete skeleton, was dated to be around 14–15 million years old. Brygmophyseter is thought to have been 7 meters (23 ft) long, and it probably had 11 or 12 teeth in the upper and lower jaws. Brygmophyseter is part of a group of macroraptorial sperm whales (often shortened to "raptorial") which tended to be apex predators using their large teeth to catch struggling prey such as whales. It had a spermaceti organ which was probably used for biosonar like in the modern sperm whale. The whale has made an appearance on The History Channel's TV series Jurassic Fight Club. (Full article...)
Skeleton at the Museo Capellini di Bologna
Orcinus citoniensis is an extinct species of killer whale identified in the Late Pliocene of Italy and the Early Pleistocene of England. It was smaller than the modern killer whale (O. orca), 4 m (13 ft) versus 7 to 10 m (23 to 33 ft), and had around 8 more teeth in its jaw. It may have resembled the modern killer whale in appearance, and could represent a transitional species between the modern killer whale and other dolphins. O. citoniensis may have hunted large fish and squid in pods, and coexisted with other large predators of the time such as the orcinine Hemisyntrachelus and the extinct shark Otodus megalodon. (Full article...)
The dusky dolphin (Lagenorhynchus obscurus) is a dolphin found in coastal waters in the Southern Hemisphere. Its specific epithet is Latin for "dark" or "dim". It is very closely genetically related to the Pacific white-sided dolphin, but current scientific consensus holds they are distinct species. The dolphin's range is patchy, with major populations around South America, southwestern Africa, New Zealand, and various oceanic islands, with some sightings around southern Australia and Tasmania. The dusky dolphin prefers cool currents and inshore waters, but can also be found offshore. It feeds on a variety of fish and squid species and has flexible hunting tactics. The dusky dolphin is known for its remarkable acrobatics, having a number of aerial behaviours. The status of the dolphin is unknown, but it has been commonly caught in gill nets. (Full article...)
The sperm whale or cachalot (Physeter macrocephalus) is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus Physeter and one of three extant species in the sperm whale family, along with the pygmy sperm whale and dwarf sperm whale of the genus Kogia.
The sperm whale is a pelagic mammal with a worldwide range, and will migrate seasonally for feeding and breeding. Females and young males live together in groups, while mature males (bulls) live solitary lives outside of the mating season. The females cooperate to protect and nurse their young. Females give birth every four to twenty years, and care for the calves for more than a decade. A mature sperm whale has few natural predators, although calves and weakened adults are sometimes killed by pods of killer whales (orcas). (Full article...)
The humpback whale (Megaptera novaeangliae) is a species of baleen whale. It is one of the larger rorqual species, with adults ranging in length from 12–16 m (39–52 ft) and weighing around 25–30 t (28–33 short tons). The humpback has a distinctive body shape, with long pectoral fins and a knobbly head. It is known for breaching and other distinctive surface behaviors, making it popular with whale watchers. Males produce a complex song lasting 10 to 20 minutes, which they repeat for hours at a time. All the males in a group will produce the same song, which is different each season. Its purpose is not clear, though it may help induce estrus in females.
Found in oceans and seas around the world, humpback whales typically migrate up to 25,000 km (16,000 mi) each year. They feed in polar waters, and migrate to tropical or subtropical waters to breed and give birth, fasting and living off their fat reserves. Their diet consists mostly of krill and small fish. Humpbacks have a diverse repertoire of feeding methods, including the bubble net technique. (Full article...)
The blue whale (Balaenoptera musculus) is a marine mammal belonging to the baleen whale parvorder Mysticeti. Reaching a maximum confirmed length of 29.9 metres (98 ft) and weighing up to 199 tonnes (196 long tons; 219 short tons), it is the largest animal known to have ever existed. The blue whale's long and slender body can be various shades of greyish-blue dorsally and somewhat lighter underneath.
The Society for Marine Mammalogy's Committee on Taxonomy currently recognizes four subspecies: B. m. musculus in the North Atlantic and North Pacific, B. m. intermedia in the Southern Ocean, B. m. brevicauda (the pygmy blue whale) in the Indian Ocean and South Pacific Ocean, B. m. indica in the Northern Indian Ocean. There is also a population in the waters off Chile that may constitute a fifth subspecies. (Full article...)
Rice's whale in the Gulf of Mexico
Rice's whale (Balaenoptera ricei) is a species of baleen whale endemic to the northern Gulf of Mexico. It was previously identified as a subpopulation of the Bryde's whale and called the Gulf of Mexico whale. Genetic and skeletal studies found it to be a distinct species by 2021. In outward appearance, it is virtually identical to the Bryde's whale. Its body is streamlined and sleek, with a uniformly dark charcoal gray dorsal and pale to pinkish underside. A diagnostic feature often used by field scientists to distinguish Rice's whales from whales other than the Bryde's whale is the three prominent ridges that line the top of its head. The species can be distinguished from the Bryde's whale by the shape of the nasal bones, which have wider gaps due to a unique wrapping by the frontal bones, its unique vocal repertoire, and genetic differences.
It is a medium-sized baleen whale that grows up to 12.65 meters (41.5 ft) in length and weighs up to 13.87–27.2 metric tons (13.65–26.77 long tons; 15.29–29.98 short tons). The Rice's whale inhabits a restricted stretch along the continental slope in the northeastern part of the Gulf of Mexico between depths of 150–410 meters (490–1,350 ft) off the coast of western Florida, although some whales have been sighted in the northwestern portions and the species may have inhabited a wider distribution throughout the Gulf in historical times. It does not migrate but remains within this area year-round. Little is known about the feeding behavior of Rice's whales, but data from a tagged individual revealed a diel vertical diving pattern, in which the whale spends most of the day feeding at or near the seafloor at depths of up to 271 meters (889 ft) and night at the surface. The whale's diet remains unknown, but lanternfish and hatchetfish are suspected prey. (Full article...)
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A Blue whale skeleton, outside the Long Marine Laboratory at the University of California, Santa Cruz.
Blue Whales are the largest animal ever to have existed. Hunting of Blue Whales has led to a severe decline in numbers across the globe.
More did you know...
- ...cetaceans have evolved from land mammals. Evidence of this is seen in the vestigial hip bones, as well in the pentadactyl ("five-fingered") dorsal flippers/fins.
- ...Herman Melville included an objective study of the properties of whales in Moby-Dick.
- ...a male dolphin named Cinderella was unofficially married to a human woman.
- ...sound made by whales can be extremely loud, with 163 decibels recorded.
- ...about 2000 whales may be beached each year.
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General images -
Humpback whale illustration
Antarctic minke whale illustration
World population graph of blue whales
Biosonar by cetaceans (from Toothed whale)
Female right whale with calf
A humpback whale skeleton. Notice how the jaw is split into two.
Gray whale illustration
Archaeocetes (like this Basilosaurus) had a heterodont dentition (from Evolution of cetaceans)
A whale as depicted by Conrad Gesner, 1587, in Historiae animalium (from Toothed whale)
A killer whale by the name of Ulises performing at SeaWorld, 2009 (from Toothed whale)
Diagram illustrating sound generation, propagation and reception in a toothed whale. Outgoing sounds are red and incoming ones are green (from Toothed whale)
Anatomy of the bottlenose dolphin (from Toothed whale)
Their eyes are relatively small for their size.
Megalodon hunted Miocene baleen whales (from Baleen whale)
The heart of a blue whale with a person standing next to it
Bowhead whale illustration
Bryde's whale (rorqual) (from Baleen whale)
Archaeomysticetes, like Janjucetus, had teeth.
Japanese scientific whaling on a pair of Antarctic minke whales (from Baleen whale)
Humpback whale breaching (from Baleen whale)
Spectrogram of dolphin vocalizations. Whistles, whines, and clicks are visible as upside down V's, horizontal striations, and vertical lines, respectively. (from Toothed whale)
Possible relationships between cetaceans and other ungulate groups. (from Evolution of cetaceans)
Pygmy right whale illustration
Dolphins (aquatic mammals) and ichthyosaurs (extinct marine reptiles) share a number of unique adaptations for fully aquatic lifestyle and are frequently used as extreme examples of convergent evolution (from Evolution of cetaceans)
The skeleton of a bowhead whale with the hind limb and pelvic bone structure circled in red. This bone structure stays internal during the entire life of the species. (from Evolution of cetaceans)
South Atlantic right whale illustration
Orange whale lice on a right whale
Atlantic white-sided dolphin caught in a drive hunt in Hvalba on the Faroe Islands being taken away with a forklift (from Toothed whale)
The nose of the whale is filled with a waxy substance that was widely used in candles, oil lamps, and lubricants (from Toothed whale)
Features of a sperm whale skeleton (from Toothed whale)
Bottlenose dolphin (from Toothed whale)
A protest against Japan's scientific whaling
Baleen whales vary considerably in size and shape, depending on their feeding behavior. (from Baleen whale)
A phylogenetic tree showing the relationships among cetacean families. (from Evolution of cetaceans)
Restoration of Janjucetus hunderi (from Baleen whale)
Sei whale illustration
Humpback whales lunge-feeding in the course of bubble net fishing
North Atlantic right whale illustration
Fossil of Squalodon (from Toothed whale)
The remains of a North Atlantic right whale after it collided with a ship propeller
Killer whale hunting a Weddel seal (from Toothed whale)
Pakicetus attocki skeleton (from Evolution of cetaceans)
Accessory baleen plates taper off into small hairs (from Baleen whale)
Eden's whale illustration
Acrophyseter skull (from Evolution of cetaceans)
Common minke whale illustration
Fin whale illustration
Blue whale illustration
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Did you know (auto-generated)
- ... that Virginia Crosbie, the member of Parliament for Ynys Môn, is a former dolphin trainer?
- ... that the three dolphins on the coat of arms of Anguilla represent "unity, strength and endurance", which is also the motto of the territory?
- ... that the forward-facing incisors of the extinct dolphin Ankylorhiza may have been used for ramming their prey, similar to a hunting method used by modern orcas?
- ... that the judiciary of the Philippines has recognized the legal standing of dolphins?
- ... that the Tugnet Ice House, the largest surviving ice house in the UK, is now a dolphin watching centre?
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