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99-556: See text Kentriodontidae is an extinct family of odontocete whales related to modern dolphins . The Kentriodontidae lived from the Oligocene to the Pliocene before going extinct . Kentriodontids have been variously divided into three or four subfamilies: Kampholophinae, Kentriodontinae, Lophocetinae, and Pithanodelphinae. However, some cladistic studies have recovered Kentriodontidae as paraphyletic while others have recovered

198-417: A basic tool. When searching for food on the sea floor, many of these dolphins were seen tearing off pieces of sponge and wrapping them around their rostra , presumably to prevent abrasions and facilitate digging. Whales use a variety of sounds for their communication and sensation. Odontocete (toothed whale) vocal production is classified in three categories: clicks, whistles, and pulsed calls: There

297-426: A broad range of sounds using nasal airsacs located just below the blowhole. Clicks are directional and are used for echolocation, often occurring in a short series called a click train. The click rate increases when approaching an object of interest. Toothed whale biosonar clicks are amongst the loudest sounds made by marine animals . The cetacean ear has specific adaptations to the marine environment. In humans,

396-444: A burst of air into the water and allowing it to rise to the surface, forming a ring, or swimming repeatedly in a circle and then stopping to inject air into the helical vortex currents thus formed. They also appear to enjoy biting the vortex rings, so that they burst into many separate bubbles and then rise quickly to the surface. Dolphins are known to use this method during hunting. Dolphins are also known to use tools. In Shark Bay ,

495-421: A burst of air into the water and allowing it to rise to the surface, forming a ring; or swimming repeatedly in a circle and then stopping to inject air into the helical vortex currents thus formed. The dolphin will often then examine its creation visually and with sonar. They also appear to enjoy biting the vortex-rings they have created, so that they burst into many separate normal bubbles and then rise quickly to

594-488: A clade phylogenetically intermediate between Kentriodon and derived delphinidans ((Inioidea+Lipotidae)+Delphinoidea). Peredo et al. (2018) restrict Kentriodon to Kampholophos , Kentriodon , Rudicetus , and Wimahl , and remove Pithanodelphininae and its putative constituent genera ( Leptodelphis , Pithanodelphis , Sarmatodelphis , Sophianacetus , and Tagicetus ) as well as Microphocaena from Kentriodontidae. This prehistoric cetacean -related article

693-441: A community are all linked either directly or through a mutual association in an overall social structure known as fission-fusion . Groups of the strongest association are known as "bands", and their composition can remain stable over years. There is some genetic evidence that band members may be related, but these bands are not necessarily limited to a single matrilineal line. There is no evidence that bands compete with each other. In

792-662: A distressed dolphin approached human divers seeking assistance. Aside from having exhibited the ability to learn complex tricks, dolphins have also demonstrated the ability to produce creative responses. This was studied by Karen Pryor during the mid-1960s at Sea Life Park in Hawaii, and was published as The Creative Porpoise: Training for Novel Behavior in 1969. The two test subjects were two rough-toothed dolphins ( Steno bredanensis ), named Malia (a regular show performer at Sea Life Park) and Hou (a research subject at adjacent Oceanic Institute). The experiment tested when and whether

891-439: A few, like the orca , feed on mammals, such as pinnipeds . Males typically mate with multiple females every year, making them polygynous . Females mate every two to three years. Calves are typically born in the spring and summer, and females bear the responsibility for raising them, but more sociable species rely on the family group to care for calves. Many species, mainly dolphins, are highly sociable, with some pods reaching over

990-425: A male bottlenose dolphin tends to be similar to that of his mother, while the signature whistle of a female bottlenose dolphin tends to be more identifying. Bottlenose dolphins have a strong memory when it comes to these signature whistles, as they are able to relate to a signature whistle of an individual they have not encountered for over twenty years. Research done on signature whistle usage by other dolphin species

1089-432: A mirror; then whether the animal shows signs of self-recognition is determined. In 1995, Marten and Psarakos used television to test dolphin self-awareness. They showed dolphins real-time footage of themselves, recorded footage, and another dolphin. They concluded that their evidence suggested self-awareness rather than social behavior. While this particular study has not been repeated since then, dolphins have since "passed"

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1188-460: A more limited capacity for colour vision than most mammals. Most toothed whales have slightly flattened eyeballs, enlarged pupils (which shrink as they surface to prevent damage), slightly flattened corneas, and a tapetum lucidum ; these adaptations allow for large amounts of light to pass through the eye, and, therefore, a very clear image of the surrounding area. In water, a whale can see around 10.7 m (35 ft) ahead of itself, but they have

1287-410: A population of Indo-Pacific bottlenose dolphins put sponges on their beak to protect them from abrasions and sting ray barbs while foraging in the seafloor. This behaviour is passed on from mother to daughter, and it is only observed in 54 female individuals. Self-awareness is seen, by some, to be a sign of highly developed, abstract thinking. Self-awareness, though not well-defined scientifically,

1386-436: A range of frequencies much wider than humans can means that sophisticated equipment, which was scarcely available in the past, is needed to record and analyse them. For example, clicks can contain significant energy in frequencies greater than 110 kHz (for comparison, it is unusual for a human to be able to hear sounds above 20 kHz), requiring that equipment have a sampling rates of at least 220 kHz; MHz -capable hardware

1485-508: A similar manner to which humans perform " audience waves ". This is achieved by sight, and possibly also echolocation. One hypothesis proposed by Jerison (1986) is that members of a pod of dolphins are able to share echolocation results with each other to create a better understanding of their surroundings. Southern resident orcas in British Columbia, Canada, and Washington, United States, live in extended family groups. The basis of

1584-438: A small bulge sitting on top of its skull, whereas a sperm whale's head is filled mainly with the melon. Directional asymmetry in the skull has been seen amongst many generations, used for echolocation. This asymmetry is useful in focusing the use of bio sonar effectively when deep diving for prey. Odontocetes are well adapted to hear sounds at ultrasonic frequencies, as opposed to mysticetes who generally hear sounds within

1683-570: A smaller range above water. They also have glands on the eyelids and outer corneal layer that act as protection for the cornea. The olfactory lobes are absent in toothed whales, and unlike baleen whales, they lack the vomeronasal organ , suggesting they have no sense of smell. Toothed whales are not thought to have a good sense of taste, as their taste buds are atrophied or missing altogether. However, some dolphins have preferences between different kinds of fish, indicating some sort of attachment to taste. Toothed whales are capable of making

1782-541: A specific individual. These whistles are used in order for dolphins to communicate with one another by identifying an individual. It can be seen as the dolphin equivalent of a name for humans. These signature whistles are developed during a dolphin's first year; it continues to maintain the same sound throughout its lifetime. An auditory experience influences the whistle development of each dolphin. Dolphins are able to communicate to one another by addressing another dolphin through mimicking their whistle. The signature whistle of

1881-575: A thousand individuals. Once hunted for their products, cetaceans are now protected by international law. Some species are very intelligent . At the 2012 meeting of the American Association for the Advancement of Science , support was reiterated for a cetacean bill of rights, listing cetaceans as nonhuman persons . Besides whaling and drive hunting , they also face threats from bycatch and marine pollution. The baiji , for example,

1980-613: A unique whistle that functions like a name, allowing the marine mammals to keep close social bonds. The new research shows that dolphins have the longest memory yet known in any species other than humans . Self-awareness , though not well defined scientifically, is believed to be the precursor to more advanced processes like meta-cognitive reasoning (thinking about thinking) that are typical of humans. Scientific research in this field has suggested that bottlenose dolphins , alongside elephants and great apes , possess self-awareness. The most widely used test for self-awareness in animals

2079-452: A way that the animal's body shape is restored, and infection of such large wounds are rare. Toothed whales are fully aquatic creatures, which means their birth and courtship behaviours are very different from terrestrial and semiaquatic creatures. Since they are unable to go onto land to calve, they deliver their young with the fetus positioned for tail-first delivery. This prevents the calf from drowning either upon or during delivery. To feed

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2178-400: A year, dependency until one to two years, and maturity around seven to 10 years, all varying between the species. This mode of reproduction produces few offspring, but increases the survival probability of each one. Females, referred to as "cows", carry the responsibility of childcare, as males, referred to as "bulls", play no part in raising calves. Cetacean intelligence Brain size

2277-402: Is a stub . You can help Misplaced Pages by expanding it . Odontoceti The toothed whales (also called odontocetes , systematic name Odontoceti ) are a clade of cetaceans that includes dolphins , porpoises , and all other whales with teeth , such as beaked whales and the sperm whales . 73 species of toothed whales are described. They are one of two living groups of cetaceans,

2376-536: Is a voluntary breather , even during sleep, with the result that veterinary anaesthesia of dolphins would result in asphyxiation . Ridgway reports that EEGs show alternating hemispheric asymmetry in slow waves during sleep, with occasional sleep-like waves from both hemispheres. This result has been interpreted to mean that dolphins sleep only one hemisphere of their brain at a time, possibly to control their voluntary respiration system or to be vigilant for predators. The dolphin's greater dependence on sound processing

2475-410: Is a socially–determined vocal tradition. The complex vocal communication systems of orcas correspond with their large brains and complex social structure. The three southern resident orca pods share some calls with one another, and also have unique calls. Discussing the function of resident orca dialects, researchers John Ford, Graeme Ellis and Ken Balcomb wrote, "It may well be that dialects are used by

2574-408: Is believed to be the precursor to more advanced processes like metacognitive reasoning (thinking about thinking) that are typical of humans. Research in this field has suggested that cetaceans, among others, possess self-awareness. The most widely used test for self-awareness in animals is the mirror test , in which a temporary dye is placed on an animal's body, and the animal is then presented with

2673-474: Is considered functionally extinct by IUCN , with the last sighting in 2004, due to heavy pollution to the Yangtze River . Whales sometimes feature in literature and film, as in the great white sperm whale of Herman Melville 's Moby-Dick . Small odontocetes, mainly dolphins, are kept in captivity and trained to perform tricks. Whale watching has become a form of tourism around the world. The tube in

2772-404: Is evident in the structure of its brain: its neural area devoted to visual imaging is only about one-tenth that of the human brain, while the area devoted to acoustical imaging is about 10 times as large. Sensory experiments suggest a great degree of cross-modal integration in the processing of shapes between echolocative and visual areas of the brain. The evolution of encephalization in cetaceans

2871-440: Is herding, where a pod squeezes a school of fish into a small volume, known as a bait ball . Individual members then take turns plowing through the ball, feeding on the stunned fish. Coralling is a method where dolphins chase fish into shallow water to catch them more easily. Orcas and bottlenose dolphins have also been known to drive their prey onto a beach to feed on it, a behaviour known as beach or strand feeding. The shape of

2970-803: Is often used. In addition to the acoustic communication channel, the visual modality is also significant. The contrasting pigmentation of the body may be used, for example with "flashes" of the hypopigmented ventral area of some species, as can the production of bubble streams during signature whistling. Also, much of the synchronous and cooperative behaviors, as described in the Behavior section of this entry, as well as cooperative foraging methods, likely are managed at least partly by visual means. Experiments have shown that they can learn human sign language and can use whistles for 2-way human–animal communication . Phoenix and Akeakamai , bottlenose dolphins, understood individual words and basic sentences like "touch

3069-412: Is one of the most accessible species for early cetologists , because it could be seen very close to land, inhabiting shallow coastal areas of Europe. Many of the findings that apply to all cetaceans were therefore first discovered in the porpoises. One of the first anatomical descriptions of the airways of the whales on the basis of a harbor porpoise dates from 1671 by John Ray. It nevertheless referred to

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3168-449: Is only a single set of functional teeth (monophyodont dentition). Except for the sperm whale, most toothed whales are smaller than the baleen whales. The teeth differ considerably among the species. They may be numerous, with some dolphins bearing over 100 teeth in their jaws. At the other extreme are the narwhals with their single long tusks and the almost toothless beaked whales with tusk-like teeth only in males. In most beaked whales

3267-405: Is relatively limited. The research on other species done so far has yielded varied outcomes and inconclusive results. Sperm whales can produce three specific vocalisations: creaks, codas, and slow clicks. A creak is a rapid series of high-frequency clicks that sounds somewhat like a creaky door hinge. It is typically used when homing in on prey. A coda is a short pattern of 3 to 20 clicks that

3366-401: Is similar to that in primates. Though the general trend in their evolutionary history increased brain mass, body mass, and encephalization quotient, a few lineages actually underwent decephalization, although the selective pressures that caused this are still under debate. Among cetaceans, Odontoceti tend to have higher encephalization quotients than Mysticeti, which is at least partially due to

3465-402: Is strong evidence that some specific whistles, called signature whistles , are used by dolphins to identify and/or call each other; dolphins have been observed emitting both other specimens' signature whistles, and their own. A unique signature whistle develops quite early in a dolphin's life, and it appears to be created in imitation of the signature whistle of the dolphin's mother. Imitation of

3564-520: Is the mirror test , developed by Gordon Gallup in the 1970s, in which a temporary dye is placed on an animal's body, and the animal is then presented with a mirror. In 1995, Marten and Psarakos used television to test dolphin self-awareness. They showed dolphins real-time footage of themselves, recorded footage, and another dolphin. They concluded that their evidence suggested self-awareness rather than social behavior. While this particular study has not been repeated since then, dolphins have since passed

3663-462: Is unknown whether every member of the group is acquainted with every other. However, large packs can act as a single cohesive unit – observations show that if an unexpected disturbance, such as a shark approach, occurs from the flank or from beneath the group, the group moves in near-unison to avoid the threat. This means that the dolphins must be aware not only of their near neighbors but also of other individuals nearby – in

3762-400: Is used in social situations to identify one another (like a signature whistle), but it is still unknown whether sperm whales possess individually specific coda repertoires or whether individuals make codas at different rates. Slow clicks are heard only in the presence of males (it is not certain whether females occasionally make them). Males make a lot of slow clicks in breeding grounds (74% of

3861-464: Is well adapted for both air and water, so much so that some can survive even if they are blind. Some species are well adapted for diving to great depths. Almost all have a layer of fat, or blubber , under the skin to keep warm in the cold water, with the exception of river dolphins . Toothed whales consist of some of the most widespread mammals, but some, as with the vaquita, are restricted to certain areas. Odontocetes feed largely on fish and squid, but

3960-519: Is well-adapted for hunting Arctic whales and calves. Bears are known to use sit-and-wait tactics, as well as active stalking and pursuit of prey on ice or water. Whales lessen the chance of predation by gathering in groups. This, however, means less room around the breathing hole as the ice slowly closes the gap. When out at sea, whales dive out of the reach of surface-hunting orca. Polar bear attacks on belugas and narwhals are usually successful in winter, but rarely inflict any damage in summer. For most of

4059-560: The 2 ⁄ 3 or 3 ⁄ 4 exponent of body mass. Comparison of actual brain size with the size expected from allometry provides an encephalization quotient (EQ) that can be used as a more accurate indicator of an animal's intelligence. Spindle cells (neurons without extensive branching) have been discovered in the brains of the humpback whale , fin whale , sperm whale , orca, bottlenose dolphins , Risso's dolphins , and beluga whales . Humans, great apes, and elephants, species all well known for their high intelligence, are

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4158-401: The artiodactyl order (even-toed ungulates). They are closely related to the hippopotamus , sharing a common ancestor that lived around 54 million years ago (mya). The primitive cetaceans, or archaeocetes , first took to the sea approximately 49 mya and became fully aquatic by 5–10 million years later. The ancestors of toothed whales and baleen whales diverged in the early Oligocene. This

4257-613: The colossal squid , octopuses , and fish like demersal rays , but their diet is mainly medium-sized squid . Some prey may be taken accidentally while eating other items. A study in the Galápagos found that squid from the genera Histioteuthis (62%), Ancistrocheirus (16%), and Octopoteuthis (7%) weighing between 12 and 650 grams (0.026 and 1.433 lb) were the most commonly taken. Battles between sperm whales and giant squid or colossal squid have never been observed by humans; however, white scars are believed to be caused by

4356-413: The middle ear works as an impedance equalizer between the outside air's low impedance and the cochlear fluid's high impedance. In whales, and other marine mammals, no great difference exists between the outer and inner environments. Instead of sound passing through the outer ear to the middle ear, whales receive sound through the throat, from which it passes through a low-impedance, fat-filled cavity to

4455-405: The southern resident orca social structure is the matriline, consisting of a matriarch and her descendants of all generations. A number of matrilines form a southern resident orca pod, which is ongoing and extremely stable in membership, and has its own dialect which is stable over time. A southern resident calf is born into the pod of their mother and remains in it for life. A cetacean dialect

4554-449: The acquisition of females for mating. The complex social strategies of marine mammals such as bottlenose dolphins, "provide interesting parallels" with the social strategies of elephants and chimpanzees. Dolphins are known to engage in complex play behavior, which includes such things as producing stable underwater toroidal air-core vortex rings or " bubble rings ". There are two main methods of bubble ring production: rapid puffing of

4653-434: The average human brain which averages 1,450 cm (88 in ) in mature males. The brain to body mass ratio in some odontocetes, such as belugas and narwhals, is second only to humans. Dolphins are known to engage in complex play behaviour , which includes such things as producing stable underwater toroidal air-core vortex rings or " bubble rings ". Two main methods of bubble ring production are: rapid puffing of

4752-451: The brain homologous to where they are found in humans, suggesting they perform a similar function. Brain size was previously considered a major indicator of the intelligence of an animal. Since most of the brain is used for maintaining bodily functions, greater ratios of brain to body mass may increase the amount of brain mass available for more complex cognitive tasks. Allometric analysis indicates that mammalian brain size scales around

4851-399: The concentration of myoglobin than haemoglobin. Before going on long dives, many toothed whales exhibit a behaviour known as sounding; they stay close to the surface for a series of short, shallow dives while building their oxygen reserves, and then make a sounding dive. Toothed whale eyes are relatively small for their size, yet they do retain a good degree of eyesight. Also, the eyes are on

4950-442: The day's session. At the start of each new day Malia would present the prior day's behavior, but only when a new behavior was exhibited was a reward given. All behaviors exhibited were, at least for a time, known behaviors of dolphins. After approximately two weeks Malia apparently exhausted "normal" behaviors and began to repeat performances. This was not rewarded. According to Pryor, the dolphin became almost despondent. However, at

5049-441: The dolphin to the sperm whale's spermaceti organ . These send out high-frequency clicks through the sound-modifying organs of the extramandibular fat body, intramandibular fat body and the melon . The melon consists of fat, and the skull of any such creature containing a melon will have a large depression. The melon size varies between species, the bigger it is, the more dependent they are on it. A beaked whale, for example, has

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5148-410: The dolphins would identify that they were being rewarded (with fish) for originality in behavior and was very successful. However, since only two dolphins were involved in the experiment, the study is difficult to generalize. Starting with the dolphin named Malia, the method of the experiment was to choose a particular behavior exhibited by her each day and reward each display of that behavior throughout

5247-550: The emergence of echolocation, or an increase in territorial range. Some research shows that dolphins, among other animals, understand concepts such as numerical continuity, though not necessarily counting. Dolphins may be able to discriminate between numbers. Several researchers observing animals' ability to learn set formation tend to rank dolphins at about the level of elephants in intelligence, and show that dolphins do not surpass other highly intelligent animals in problem solving. A 1982 survey of other studies showed that in

5346-409: The exception sperm whales), and eyes placed on the sides of their heads. Toothed whales range in size from the 4.5 ft (1.4 m) and 120 lb (54 kg) vaquita to the 20 m (66 ft) and 55 t (61-short-ton) sperm whale. Overall, they tend to be dwarfed by their relatives, the baleen whales (Mysticeti). Several species have sexual dimorphism, with the females being larger than

5445-419: The fact that Mysticeti have much larger body masses without a compensating increase in brain mass. As far as which selective pressures drove the encephalization (or decephalization) of cetacean brains, current research espouses a few main theories. The most promising suggests that cetacean brain size and complexity increased to support complex social relations. It could also have been driven by changes in diet,

5544-409: The family as monophyletic. For instance, Miminiacetus may be a close relative of Lipotidae , Brevirostrodelpis is basal to other delphinidans, Incacetus is probably a member of Inioidea , and Atocetus and Lophocetus have been recovered as a pontoporiid and ziphiid sister taxon respectively, while Hadrodelphis , Kampholophos , Macrokentriodon , and Miminiacetus are recovered in

5643-461: The frisbee with your tail and then jump over it". Phoenix learned whistles, and Akeakamai learned sign language. Both dolphins understood the significance of the ordering of tasks in a sentence. A study conducted by Jason Bruck of the University of Chicago showed that bottlenose dolphins can remember whistles of other dolphins they had lived with after 20 years of separation. Each dolphin has

5742-475: The front, and a tail fin. These flippers contain four digits. Although toothed whales do not possess fully developed hind limbs, some, such as the sperm whale, possess discrete rudimentary appendages, which may contain feet and digits. Toothed whales are fast swimmers in comparison to seals, which typically cruise at 5–15 knots, or 9–28 km/h (5.6–17.4 mph); the sperm whale, in comparison, can travel at speeds of up to 35 km/h (22 mph). The fusing of

5841-548: The growth of the neocortex , both absolutely and relative to the rest of the brain, during human evolution, has been responsible for the evolution of human intelligence, however defined. While a complex neocortex usually indicates high intelligence, there are exceptions. For example, the echidna has a highly developed brain, yet is not widely considered very intelligent, though preliminary investigations into their intelligence suggest that echidnas are capable of more advanced cognitive tasks than were previously assumed. In 2014, it

5940-484: The harsh climate. Calves are born with only a thin layer of blubber, but some species compensate for this with thick lanugos . Toothed whales have also evolved the ability to store large amounts of wax esters in their adipose tissue as an addition to or in complete replacement of other fats in their blubber. They can produce isovaleric acid from branched chain fatty acids (BCFA). These adaptations are unique, are only in more recent, derived lineages and were likely part of

6039-551: The head, through which this kind fish takes its breath and spitting water, located in front of the brain and ends outwardly in a simple hole, but inside it is divided by a downward bony septum, as if it were two nostrils; but underneath it opens up again in the mouth in a void. –John Ray, 1671, the earliest description of cetacean airways In Aristotle 's time, the fourth century BC, whales were regarded as fish due to their superficial similarity. Aristotle, however, could already see many physiological and anatomical similarities with

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6138-406: The inner ear. The ear is acoustically isolated from the skull by air-filled sinus pockets, which allow for greater directional hearing underwater. Odontocetes generate sounds independently of respiration using recycled air that passes through air sacs and phonic (alternatively monkey) lips. Integral to the lips are oil-filled organs called dorsal bursae that have been suggested to be homologous in

6237-900: The large squid. A 2010 study suggests that female sperm whales may collaborate when hunting Humboldt squid . The orca is known to prey on numerous other toothed whale species. One example is the false killer whale . To subdue and kill whales, orcas continually ram them with their heads; this can sometimes kill bowhead whales , or severely injure them. Other times, they corral their prey before striking. They are typically hunted by groups of 10 or fewer orca, but they are seldom attacked by an individual. Calves are more commonly taken by orca, but adults can be targeted, as well. Groups even attack larger cetaceans such as minke whales , gray whales , and rarely sperm whales or blue whales . Other marine mammal prey species include nearly 20 species of seal , sea lion and fur seal . These cetaceans are targeted by terrestrial and pagophilic predators. The polar bear

6336-492: The learning of "set formation", dolphins rank highly, but not as high as some other animals. Dolphin group sizes vary quite dramatically. River dolphins usually congregate in fairly small groups from 6 to 12 in number or, in some species, singly or in pairs. The individuals in these small groups know and recognize one another. Other species such as the oceanic pantropical spotted dolphin , common dolphin and spinner dolphin travel in large groups of hundreds of individuals. It

6435-465: The lungs meets cold air, so it does not form in warmer climates, as with river dolphins. Almost all cetaceans have a thick layer of blubber , except for river dolphins. In species that live near the poles, the blubber can be as thick as 11 in (28 cm). This blubber can help with buoyancy, protection to some extent as predators would have a hard time getting through a thick layer of fat, energy for fasting during leaner times, and insulation from

6534-423: The males. One exception is with the sperm whale, which has males larger than the females. Odontocetes possess teeth with cementum cells overlying dentine cells. Unlike human teeth, which are composed mostly of enamel on the portion of the tooth outside of the gum, whale teeth have cementum outside the gum. Only in larger whales, where the cementum is worn away on the tip of the tooth, does enamel show. There

6633-431: The melon-shaped forehead, reflected off objects, and retrieved through the lower jaw. Skulls of Squalodon show evidence for the first hypothesized appearance of echolocation. Squalodon lived from the early to middle Oligocene to the middle Miocene , around 33-14 mya. Squalodon featured several commonalities with modern Odontocetes. The cranium was well compressed, the rostrum telescoped outward (a characteristic of

6732-403: The mirror test. Dolphins make a broad range of sounds using nasal airsacs located just below the blowhole. Roughly three categories of sounds can be identified: frequency modulated whistles, burst-pulsed sounds and clicks. Dolphins communicate with whistle-like sounds produced by vibrating connective tissue, similar to the way human vocal cords function, and through burst-pulsed sounds, though

6831-462: The modern parvorder Odontoceti ), giving Squalodon an appearance similar to that of modern toothed whales. However, it is thought unlikely that squalodontids are direct ancestors of living dolphins. Toothed whales have torpedo-shaped bodies with usually inflexible necks, limbs modified into flippers, no outer ears, a large tail fin, and bulbous heads (with the exception of the sperm whale family ). Their skulls have small eye orbits, long beaks (with

6930-403: The nature and extent of that ability is not known. The clicks are directional and are for echolocation, often occurring in a short series called a click train. The click rate increases when approaching an object of interest. Dolphin echolocation clicks are amongst the loudest sounds made by marine animals. Bottlenose dolphins have been found to have signature whistles, a whistle that is unique to

7029-536: The neck vertebrae, while increasing stability when swimming at high speeds, decreases flexibility, rendering them incapable of turning their heads; river dolphins, however, have unfused neck vertebrae and can turn their heads. When swimming, toothed whales rely on their tail fins to propel them through the water. Flipper movement is continuous. They swim by moving their tail fin and lower body up and down, propelling themselves through vertical movement, while their flippers are mainly used for steering. Some species log out of

7128-416: The newborn, toothed whales, being aquatic, must squirt the milk into the mouth of the calf. Being mammals, they have mammary glands used for nursing calves; they are weaned around 11 months of age. This milk contains high amounts of fat which is meant to hasten the development of blubber; it contains so much fat, it has the consistency of toothpaste. Females deliver a single calf, with gestation lasting about

7227-409: The only others known to have spindle cells. Spindle neurons appear to play a central role in the development of intelligent behavior. Such a discovery may suggest a convergent evolution of these species. Elephant brains also show a complexity similar to dolphin brains, and are also more convoluted than that of humans, and with a cortex thicker than that of cetaceans. It is generally agreed that

7326-523: The orca Skana, he researched her visual skills. However, after performing favorably in the 72 trials per day, Skana suddenly began consistently getting every answer wrong. Spong concluded that a few fish were not enough motivation. He began playing music, which seemed to provide Skana with much more motivation. At the Institute for Marine Mammal Studies in Mississippi, it has also been observed that

7425-536: The original sound. In larger groups, individual whistle sounds are less prominent. Dolphins tend to travel in pods, sometimes of up to 600 members. Cetaceans are known to communicate and therefore are able to teach, learn, cooperate, scheme, and grieve. The neocortex of many species of dolphins is home to elongated spindle neurons that, prior to 2007, were known only in hominids. In humans, these cells are involved in social conduct, emotions, judgement, and theory of mind. Dolphin spindle neurons are found in areas of

7524-732: The other being the baleen whales (Mysticeti), which have baleen instead of teeth. The two groups are thought to have diverged around 34 million years ago (mya). Toothed whales range in size from the 1.4 m (4 ft 7 in) and 54 kg (119 lb) vaquita to the 20 m (66 ft) and 100 t (98 long tons; 110 short tons) sperm whale . Several species of odontocetes exhibit sexual dimorphism , in that there are size or other morphological differences between females and males. They have streamlined bodies and two limbs that are modified into flippers. Some can travel at up to 20 knots. Odontocetes have conical teeth designed for catching fish or squid. They have well-developed hearing that

7623-451: The pointing gesture, including human pointing, dolphin postural pointing, and human gaze, in the sense of a redirection of another individual's attention, an ability which may require theory of mind . The environment where dolphins live makes experiments much more expensive and complicated than for many other species; additionally, the fact that cetaceans can emit and hear sounds (which are believed to be their main means of communication) in

7722-662: The porpoise as a fish.   Sperm whales (Physeteridae) [REDACTED]   Dwarf sperm whales (Kogiidae) [REDACTED]   South Asian river dolphins (Platanistidae) [REDACTED]   Beaked whales (Ziphiidae) [REDACTED]   Yangtze river dolphin (Lipotidae) [REDACTED]   Pontoporiidae [REDACTED]   Iniidae [REDACTED]   Oceanic dolphins (Delphinidae) [REDACTED]   Porpoises  (Phocoenidae) [REDACTED]   Belugas , narwhals (Monodontidae) [REDACTED] Toothed whales, as well as baleen whales, are descendants of land-dwelling mammals of

7821-438: The range of infrasonic frequencies. Bottlenose dolphins have been found to have signature whistles unique to each individual. Dolphins use these whistles to communicate with one another by identifying an individual. It can be seen as the dolphin equivalent of a name for humans. Because dolphins generally live in groups, communication is necessary. Signal masking is when other similar sounds (conspecific sounds) interfere with

7920-548: The resident dolphins seem to show an awareness of the future. The dolphins are trained to keep their own tank clean by retrieving rubbish and bringing it to a keeper, to be rewarded with a fish. However, one dolphin, named Kelly, has apparently learned a way to get more fish, by hoarding the rubbish under a rock at the bottom of the pool and bringing it up one small piece at a time. As of 1984 , scientists have observed wild bottlenose dolphins in Shark Bay , Western Australia using

8019-471: The same research areas, as well as in Moray Firth , Scotland , males form strong associations of two to three individuals, with a coefficient of association between 70 and 100. These groups of males are known as "alliances", and members often display synchronous behaviors such as respiration, jumping, and breaching. Alliance composition is stable on the order of tens of years, and may provide a benefit for

8118-704: The same stage. On each occasion the experiment was stopped when the variability of dolphin behavior became too complex to make further positive reinforcement meaningful. The same experiment was repeated with humans, and it took the volunteers about the same length of time to figure out what was being asked of them. After an initial period of frustration or anger, the humans realised they were being rewarded for novel behavior. In dolphins this realisation produced excitement and more and more novel behaviors – in humans it mostly just produced relief. Captive orcas have displayed responses indicating they get bored with activities. For instance, when Paul Spong worked with

8217-418: The sides of the head, so their vision consists of two fields, rather than a binocular view as humans have. When a beluga surfaces, its lenses and corneas correct the nearsightedness that results from the refraction of light; they contain both rod and cone cells, meaning they can see in both dim and bright light. They do, however, lack short wavelength-sensitive visual pigments in their cone cells, indicating

8316-402: The signature whistle seems to occur only among the mother and its young, and among befriended adult males. Xitco reported the ability of dolphins to eavesdrop passively on the active echolocative inspection of an object by another dolphin. Herman calls this effect the "acoustic flashlight" hypothesis, and may be related to findings by both Herman and Xitco on the comprehension of variations on

8415-490: The sixteenth session without novel behavior, the researchers were presented with a flip they had never seen before. This was reinforced. As related by Pryor, after the new display: "instead of offering that again she offered a tail swipe we'd never seen; we reinforced that. She began offering us all kinds of behavior that we hadn't seen in such a mad flurry that finally we could hardly choose what to throw fish at". The second test subject, Hou, took thirty-three sessions to reach

8514-475: The smaller species of dolphins, only a few of the larger sharks, such as the bull shark , dusky shark , tiger shark , and great white shark , are a potential risk, especially for calves. Dolphins can tolerate and recover from extreme injuries (including shark bites) although the exact methods used to achieve this are not known. The healing process is rapid and even very deep wounds do not cause dolphins to hemorrhage to death. Even gaping wounds restore in such

8613-423: The snout may correlate with tooth number and thus feeding mechanisms. The narwhal, with its blunt snout and reduced dentition, relies on suction feeding . Sperm whales usually dive between 300 and 800 metres (980 and 2,620 ft), and sometimes 1 to 2 kilometres (3,300 to 6,600 ft), in search of food. Such dives can last more than an hour. They feed on several species, notably the giant squid , but also

8712-589: The surface. Certain whales are also known to produce bubble rings or bubble nets for the purpose of foraging. Many dolphin species also play by riding in waves, whether natural waves near the shoreline in a method akin to human "body-surfing", or within the waves induced by the bow of a moving boat in a behavior known as bow riding . There have been instances in captivity of various species of dolphin and porpoise helping and interacting across species, including helping beached whales. Dolphins have also been known to aid human swimmers in need , and in at least one instance

8811-501: The teeth are seen to erupt in the lower jaw, and primarily occurs at the males sexual maturity. Not all species are believed to use their teeth for feeding. For instance, the sperm whale likely uses its teeth for aggression and showmanship. Breathing involves expelling stale air from their one blowhole , forming an upward, steamy spout, followed by inhaling fresh air into the lungs. Spout shapes differ among species, which facilitates identification. The spout only forms when warm air from

8910-523: The terrestrial vertebrates, such as blood (circulation), lungs, uterus, and fin anatomy. His detailed descriptions were assimilated by the Romans, but mixed with a more accurate knowledge of the dolphins, as mentioned by Pliny the Elder in his Natural history . In the art of this and subsequent periods, dolphins are portrayed with a high-arched head (typical of porpoises) and a long snout. The harbor porpoise

9009-542: The time), both near the surface and at depth, which suggests they are primarily mating signals. Outside breeding grounds, slow clicks are rarely heard, and usually near the surface. All whales are carnivorous and predatory . Odontocetes, as a whole, mostly feed on fish and cephalopods , and then followed by crustaceans and bivalves . All species are generalist and opportunistic feeders. Some may forage with other kinds of animals, such as other species of whales or certain species of pinnipeds . One common feeding method

9108-425: The toothed whale lineage. Modern toothed whales do not rely on their sense of sight, but rather on their sonar to hunt prey. Echolocation also allowed toothed whales to dive deeper in search of food, with light no longer necessary for navigation, which opened up new food sources. Toothed whales (Odontocetes) echolocate by creating a series of clicks emitted at various frequencies. Sound pulses are emitted through

9207-449: The transition for species to become deeper divers as the families of toothed whales (Physeteridae, Kogiidae, and Ziphiidae) that have the highest quantities of wax esters and BCFAs in their blubber are also the species that dive the deepest and for the longest amount of time. Toothed whales have a two-chambered stomach similar in structure to terrestrial carnivores. They have fundic and pyloric chambers. Cetaceans have two flippers on

9306-439: The two-thirds or three-quarters exponent of the body mass. Comparison of a particular animal's brain size with the expected brain size based on such allometric analysis provides an encephalization quotient that can be used as another indication of animal intelligence. Sperm whales have the largest brain mass of any animal on earth, averaging 8,000 cm (490 in ) and 7.8 kg (17 lb) in mature males, in comparison to

9405-504: The water, which may allow them to travel faster. Their skeletal anatomy allows them to be fast swimmers. Most species have a dorsal fin . Most toothed whales are adapted for diving to great depths, porpoises are one exception. In addition to their streamlined bodies, they can slow their heart rate to conserve oxygen; blood is rerouted from tissue tolerant of water pressure to the heart and brain among other organs; haemoglobin and myoglobin store oxygen in body tissue; and they have twice

9504-533: The whales as acoustic indicators of group identity and membership, which might serve to preserve the integrity and cohesiveness of the social unit." Resident orcas form closed societies with no emigration or dispersal of individuals, and no gene flow with other orca populations. There is evidence that other species of dolphins may also have dialects. In bottlenose dolphin studies by Wells in Sarasota , Florida , and Smolker in Shark Bay , Australia , females of

9603-614: Was due to a change in the climate of the southern oceans that affected where the environment of the plankton that these whales ate. The adaptation of echolocation and enhanced fat synthesis in blubber occurred when toothed whales split apart from baleen whales, and distinguishes modern toothed whales from fully aquatic archaeocetes. This happened around 34 mya. 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

9702-521: Was previously considered a major indicator of the intelligence of an animal. However, many other factors also affect intelligence, and recent discoveries concerning bird intelligence have called into question the influence of brain size. Since most of the brain is used for maintaining bodily functions, greater ratios of brain to body mass may increase the amount of brain mass available for more complex cognitive tasks. Allometric analysis indicates that in general, mammalian brain size scales at approximately

9801-461: Was shown for the first time that a species of dolphin, the long-finned pilot whale , has more neocortical neurons than any mammal studied to date including humans. Unlike terrestrial mammals, dolphin brains contain a paralimbic lobe , which may possibly be used for sensory processing. It has also been suggested that similar to humans, the paralimbic region of the brain is responsible for a dolphin's self-control, motivation, and emotions. The dolphin

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