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83-445: The estuary is the habitat of a large community of bottlenose dolphins ; there are 31 members of the pod, each of whom has been named (2007). The river is dammed in several places, chiefly for irrigation of rice, maize, and vegetables. In its course, the river crosses the city of Alcácer do Sal . 38°29′22″N 8°55′24″W  /  38.4894°N 8.92333°W  / 38.4894; -8.92333 This article related to

166-413: A marine sponge on their rostrum , presumably to protect it when searching for food on the sandy sea bottom. This has only been observed in this bay (first in 1997), and is predominantly practiced by females. A 2005 study showed mothers most likely teach the behavior to their offspring, evincing culture (behavior learned from other species members). Mud plume feeding is a feeding technique performed by

249-674: A change of water flow pattern from the infant which minimizes separation between the mother and infant, but also increases the mother's surface area and creates a drag for the swimmer. This also leaves less energy to use in swimming speed, foraging, and predator evasion. Adult males live mostly alone or in groups of two to three, and join pods for short periods of time. Adult females and young dolphins normally live in groups of up to 15 animals. Males give strong mutual support if other males help them, even if they are not friends. However, they live in fission-fusion societies of varying group size , within which individuals change associations, often on

332-524: A concentrated food source. Indo-Pacific bottlenose dolphin The Indo-Pacific bottlenose dolphin ( Tursiops aduncus ) is a species of bottlenose dolphin . This dolphin grows to 2.6 m (8.5 ft) long, and weighs up to 230 kg (510 lb). It lives in the waters around India , northern Australia , South China , the Red Sea , and the eastern coast of Africa . Its back

415-556: A daily or hourly basis. Group compositions are usually determined by sex, age, reproductive condition, familial relations and affiliation histories. In a dolphin community near Sarasota, Florida , the most common group types are adult females with their recent offspring, older subadults of both sexes, and adult males either alone or in bonded pairs. Smaller groups can join to form larger groups of 100 or more, and occasionally exceed 1,000. The social strategies of marine mammals such as bottlenose dolphins "provide interesting parallels" with

498-424: A fish with its fluke, sometimes knocking it out of the water, using a strategy called "fish whacking". "Strand feeding" is an inherited feeding technique used by bottlenose dolphins near and around coastal regions of Georgia and South Carolina. When a pod finds a school of fish, they will circle the school and trap the fish in a mini whirlpool. Then, the dolphins will charge at the school and push their bodies up onto

581-672: A global scale. Prior to 1980, more than 1,500 bottlenose dolphins were collected from the United States, Mexico, and the Bahamas, and more than 550 common and 60 Indo-Pacific bottlenose dolphins were brought into captivity in Japan. By the late 1980s, the United States stopped collecting bottlenose dolphins and the number of captive-born animals in North American aquaria has increased from only 6% in 1976 to about 44% in 1996. In

664-448: A human can: the dolphin can store 36 milliliters (ml) of oxygen per kg of body weight, compared with 20 ml per kg for humans. This is an adaptation to diving. The bottlenose dolphin typically rises to the surface to breathe through its blowhole two to three times per minute, although it can remain submerged for up to 20 minutes. Dolphins can breathe while "half-asleep". During the sleeping cycle, one brain hemisphere remains active, while

747-553: A length of just over 4 m (13 ft). Its color varies considerably, is usually dark gray on the back and lighter gray on the flanks, but it can be bluish-grey, brownish-grey, or even nearly black, and is often darker on the back from the rostrum to behind the dorsal fin . This is called countershading and is a form of camouflage . Older dolphins sometimes have a few spots. Bottlenose dolphins can live for more than 40 years. Females typically live 5–10 years longer than males, with some females exceeding 60 years. This extreme age

830-456: A mud-flat, forcing the fish on the mud-flat, as well. The dolphins then crawl around on their sides, consuming the fish they washed up on shore. This happens only during low tides. One type of feeding behavior seen in bottlenose dolphins is mud ring feeding . Bottlenose dolphins conflict with small-scale coastal commercial fisheries in some Mediterranean areas. Common bottlenose dolphins are probably attracted to fishing nets because they offer

913-678: A practice known as "strand feeding". Groups of between two and six dolphins are regularly observed creating a bow wave to force the fish out of the water. The dolphins follow the fish, stranding themselves briefly, to eat their prey before twisting their bodies back and forth in order to slide back into the water. While initially documented in South Carolina and Georgia, strand feeding has also been observed in Louisiana, Texas, Baja California, Ecuador, and Australia. Some Mauritanian dolphins cooperate with human fishermen. The dolphins drive

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996-402: A rare form of self-decoration and social object use called grass-wearing. Self-decoration by wearing grass appears to be an attention-getting device rather than purely play and varies from a single blade to large clusters of grass. John's Pass dolphins self-decorate with grass primarily when they form new social groups or engage in procreative activities. Grass-wearing behavior among these dolphins

1079-470: A result of high fish density around the floating cages in the farming area. Fish is one of the main items in the dolphin diet. They also eat shrimps, squid, mollusks, and cuttlefish, and only swallow the soft parts. They eat 22 pounds of fish a day. When they encounter a shoal of fish , they work as a team to herd them towards the shore to maximize the harvest. They also hunt alone, often targeting bottom-dwelling species. The bottlenose dolphin sometimes hits

1162-501: A river in Portugal is a stub . You can help Misplaced Pages by expanding it . Bottlenose dolphin The bottlenose dolphin is a toothed whale in the genus Tursiops . They are common, cosmopolitan members of the family Delphinidae , the family of oceanic dolphins . Molecular studies show the genus contains three species : the common bottlenose dolphin ( Tursiops truncatus ),

1245-747: A school of fish towards the shore, where humans await with nets. In the confusion of casting nets, the dolphins catch a large number of fish as well. Intraspecies cooperative foraging has also been observed. These behaviors may also be transmitted via teaching. Controversially, Rendell and Whitehead have proposed a structure for the study of cetacean culture. Similar cases have been observed in Laguna, Santa Catarina in Brazil since during 19th century as well. Near Adelaide , in South Australia , several bottlenose dolphins " tail-walk ", whereby they elevate

1328-452: A series of dimples known as vibrissal pits able to sense electric fields. Dolphins have sharp eyesight. The eyes are located at the sides of the head and have a tapetum lucidum , or reflecting membrane, at the back of the retina, which aids vision in dim light. Their horseshoe-shaped, double-slit pupils enable dolphins to have good vision both in air and underwater, despite the different indices of refraction of these media. When under water,

1411-404: A short time. The dolphin's search for food is aided by a form of sonar known as echolocation : it locates objects by producing sounds and listening for the echoes. Clicking sounds are emitted in a focused beam in front of the dolphin. When the clicking sounds hit an object in the water, like a fish or rock, they bounce off and come back to the dolphin as echoes. Echolocation tells the dolphins

1494-491: A small community of bottlenose dolphins over shallow seagrass beds (less than 1 m) in the Florida Keys in the United States. The behavior involves creation of a U-shaped plume of mud in the water column and then rushing through the plume to capture fish. Along the beaches and tidal marshes of South Carolina and Georgia in the United States, bottlenose dolphins cooperatively herd prey fish onto steep and sandy banks in

1577-610: A somewhat lighter blue colour and the cape is generally more distinct, with a light spinal blaze extending to below the dorsal fin. However, although not always present, the most obvious distinction can be made with the presence of black spots or flecks on the bellies of adults of Indo-Pacific bottlenose dolphins, which are very rare in common bottlenose dolphins. Their teeth can number between 23 and 29 in each upper and lower jaw, and are more slender than those of common bottlenose dolphins. Size of Indo-Pacific bottlenose dolphins can vary based on geographic location; however, its average length

1660-563: A subspecies of T. truncatus , or a subspecies of T. aduncus . Following the results of a 2020 study, the American Society of Mammalogists presently classifies it as a subspecies of T. aduncus . The same study delineated 3 distinct lineages within T. aduncus which could each be their own subspecies: an Indian Ocean lineage, an Australasian lineage, and the Burrunan dolphin. The Society for Marine Mammalogy does not recognize

1743-493: A synonym of T. truncatus , while T. nuuanu was recognized as a subspecies. In general, genetic variation between populations is significant, even among nearby populations. As a result of this genetic variation, other distinct species currently considered to be populations of common bottlenose dolphin are possible. Much of the discussion and doubts about its taxonomy is related to the existence of two ecotypes of bottlenose dolphins in many part of its distribution. For example,

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1826-628: A third distinct species was described, the Burrunan dolphin ( T. (aduncus) australis ), found in the Port Phillip and Gippsland Lakes areas of Victoria , Australia, after research showed it was distinct from T. truncatus and T. aduncus , both in morphology and genetics. Also, evidence has been accumulating to validate the existence of a separate species, Lahille's bottlenose dolphin, T. gephyreus , that occurs in coastal waters of Argentina, Uruguay and southern Brazil. Other sources accept

1909-455: A tool. The first report and footage of spontaneous ejaculation in an aquatic mammal was recorded in a wild Indo-Pacific bottlenose dolphin near Mikura Island , Japan, in 2012. Indo-Pacific bottlenose dolphins have been observed to swim near and rub themselves against specific types of corals and sponges. A team of scientists followed up on this behavior and discovered metabolites with antibacterial, antioxidative, and hormonal activities in

1992-517: A uniquely identifying, frequency-modulated narrow-band signature vocalization ( signature whistle ). Signature whistles, which are in a higher frequency range than humans can hear, have an important role in facilitating mother–calf contact. In the Sarasota Dolphin Research Program's library of recordings were 19 female common bottlenose dolphins ( Tursiops truncatus ) producing signature whistles both with and without

2075-403: Is 2.6 m (8.5 ft) long, and it weighs up to 230 kg (510 lb). The length at birth is between 0.84 and 1.5  m (2.8 and 4.9  ft ). The local population centering Mikura-jima is claimed to be a distinct form or species. Indo-Pacific bottlenose dolphins feed on a wide variety of fish and cephalopods (particularly squid ). In one study, researchers looked at

2158-463: Is a local behavioral tradition that could constitute a cultural difference from other communities. Some researchers hypothesize that the number of nerve cells ( neurons ) in the cortex of the brain predicts intelligence in mammals . A 2019 study estimated the number of neurons in the cerebral cortex of three common bottlenose dolphins and found numbers ranging from 11.7 to 15.2 billion neurons. The human average being approximately 16 billion, this

2241-841: Is also covered by Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region ( Pacific Cetaceans MoU ). The population of the Menai Bay Conservation Area in the Zanzibar Archipelago of Tanzania has been researched. The Adelaide Dolphin Sanctuary is a marine protected area in the Australian state of South Australia located on the east coast of Gulf St Vincent , which

2324-431: Is dark grey and its belly is lighter grey or nearly white with grey spots. The Indo-Pacific bottlenose dolphin is generally smaller than the common bottlenose dolphin , has a proportionately longer rostrum , and has spots on its belly and lower sides. It also has more teeth than the common bottlenose dolphin — 23 to 29 teeth on each side of each jaw compared to 21 to 24 for the common bottlenose dolphin. Much of

2407-579: Is energetically expensive. Males have large testes in relation to their body size. During the breeding season , males compete for access to females. Such competition can take the form of fighting other males or of herding females to prevent access by other males. Male Sarasota Bay common bottlenose dolphins with the defensive advantages of male pair-bonding range more widely than unpaired males, and encounter more unrelated females. In Shark Bay, male Indo-Pacific bottlenose dolphins have been observed working in pairs or larger groups to follow and/or restrict

2490-638: Is followed by rapid conception (1–2 months), whereas conception is delayed (2–9 months) if calf loss occurs between January and July. Weaning ages ranged from 2.7 to 8.0 years, but 66.7% (42 calves) were weaned by their fourth birthday. Females tended to wean mid-pregnancy. Group size was unrelated to water depth or female reproductive success, but reproductive success was predicted by water depth. Shallow water may allow mothers and calves to detect and avoid predatory sharks. Alternatively, or additionally, prey density may be higher in shallow water compared to deep water. Georgetown University professor Janet Mann argues

2573-608: Is likely within the range found in the human population. Bottlenose dolphins have a lifespan of 40–60 years. Females can outlive males and live for 60 years or more. Dolphins start to reproduce aged 5 to 15 years. The bottlenose dolphin has a single blowhole located on the dorsal surface of the head consisting of a hole and a muscular flap. The flap is closed during muscle relaxation and opens during contraction. Dolphins are voluntary breathers, who must deliberately surface and open their blowholes to get air. They can store almost twice as much oxygen in proportion to their body weight as

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2656-504: Is rare and less than 2% of all Bottlenose dolphins will live longer than 60 years. Bottlenose dolphins can jump to a height of 6 metres (20 feet) in the air. Their elongated upper and lower jaws form what is called a rostrum, or snout, which gives the animal its common name. The real, functional nose is the blowhole on top of its head; the nasal septum is visible when the blowhole is open. Bottlenose dolphins have 18 to 28 conical teeth on each side of each jaw. The flukes (lobes of

2739-487: Is typically 4.5 to 6 years. In some parts of its range, this dolphin is subject to predation by sharks ; its lifespan is more than 40 years. Indo-Pacific bottlenose dolphins located in Shark Bay , Australia, have been observed using sponges as tools in a practice called "sponging". A dolphin breaks a marine sponge off the sea floor and wears it over its rostrum, apparently to probe substrates for fish, possibly as

2822-530: The Atlantic spotted dolphin ( S. frontalis ), than it is to the common bottlenose dolphin. However, more recent studies indicate that this is a consequence of reticulate evolution (such as past hybridization between Stenella and ancestral Tursiops ) and incomplete lineage sorting , and thus support T . truncatus and T. aduncus belonging to the same genus. The Burrunan dolphin ( T. (aduncus) australis ) has been alternately considered its own species,

2905-522: The Ending the Captivity of Whales and Dolphins Act . In a study on three populations of Indo-Pacific bottlenose dolphins in Japan, the characteristics of acoustic signals are believed to be affected by the acoustic environments among habitats, and geographical variation in animal acoustic signals can result from differences in acoustic environments; therefore, the characteristics of the ambient noise in

2988-554: The Indo-Pacific bottlenose dolphin ( Tursiops aduncus ), and Tamanend's bottlenose dolphin ( Tursiops erebennus ). 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

3071-538: The South Korea , in the 2010s, environmental groups and animal protection groups led a campaign ( 2013년 대한민국 남방큰돌고래 방사 ) to release southern bottlenose dolphins illegally captured by fishermen and trapped in Jeju Pacific Land and Seoul Zoo . In 2019, Canada banned the trade, possession, capture, and breeding of whales, dolphins, and porpoises for entertainment through passing Bill-203, also known as

3154-454: The 1950s, no "dolphin language" has been found. However, Herman , Richards, and Wolz demonstrated comprehension of an artificial language by two bottlenose dolphins (named Akeakamai and Phoenix) in the period of skepticism toward animal language following Herbert Terrace 's critique. Cognitive abilities that have been investigated include concept formation , sensory skills, and mental representations. Such research has been ongoing since

3237-485: The 1970s. This includes: acoustic and behavioral mimicry, comprehension of novel sequences in an artificial language , memory , monitoring of self behavior, discrimination and matching, comprehension of symbols for various body parts, comprehension of pointing gestures and gaze (as made by dolphins or humans), mirror self-recognition , and numerical values. At least some wild bottlenose dolphins use tools. In Shark Bay , off Western Australia , dolphins place

3320-466: The Burrunan dolphin as a distinct species or subspecies, citing the need for further research. Indo-Pacific bottlenose dolphins are very similar to common bottlenose dolphins in appearance. Common bottlenose dolphins have a reasonably strong body, moderate-length beak, and tall, curved dorsal fins; whereas Indo-Pacific bottlenose dolphins have a more slender body build and their beak is longer and more slender. The Indo-Pacific population also tends to have

3403-578: The Eastern Tropical Pacific bottlenose dolphin ( T. t. nuuanu ). The IUCN, on their Red List of endangered species, currently recognises only two species of bottlenose dolphins. The American Society of Mammalogists also recognizes only two species. While acknowledging the studies describing T. australis , it classifies it within T. aduncus . Some recent genetic evidence suggests the Indo-Pacific bottlenose dolphin belongs in

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3486-965: The Latin tursio (dolphin) and truncatus for the truncated teeth (the type specimen was old and had worn down teeth; this is not a typical characteristic of most members of the species). 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

3569-558: The Pacific bottlenose dolphin ( T. t. gillii or T. gillii ), that inhabits the Pacific, and has a black line from the eye to the forehead. T. gillii , first described in 1873, is currently considered a junior synonym of T. truncatus . Additionally, T. nuuanu was described in 1911 for bottlenose dolphins along the Pacific coast in Central America. An analysis of T. gillii and T. nuuanu specimens supported T. gillii as

3652-681: The behaviour has continued through generations until 2022. A study conducted by 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 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 . The bottlenose dolphins of John's Pass in Boca Ciega Bay, St. Petersburg, Florida , exhibit

3735-527: The brain. Bottlenose dolphins are able to detect salty, sweet, bitter ( quinine sulphate ), and sour ( citric acid ) tastes, but this has not been well-studied. Anecdotally, some individuals in captivity have been noted to have preferences for food fish types, although it is not clear if taste mediates this preference. In 2022, a study at the University of St Andrews in Scotland found that dolphins were able to identify their "friends" and family members by

3818-796: The child to pay attention, long-term bonding, and promoting the development of lifelong vocal learning , with parallels in these bottlenose dolphins in an example of convergent evolution . Researchers from the Bottlenose Dolphin Research Institute (BDRI), based in Sardinia (Italy) have now shown whistles and burst pulsed sounds are vital to the animals' social life and mirror their behaviors. The tonal whistle sounds (the most melodious ones) allow dolphins to stay in contact with each other (above all, mothers and offspring), and to coordinate hunting strategies. The burst-pulsed sounds (which are more complex and varied than

3901-520: The coastal form while the offshore form was retained in T. truncatus . The Society for Marine Mammalogy 's Committee on Taxonomy presently recognizes three species of bottlenose dolphin: T. truncatus , T. aduncus , and T. erebennus . They also recognize three subspecies of common bottlenose dolphin in addition to the nominotypical subspecies : the Black Sea bottlenose dolphin ( T. t. ponticus ), Lahille's bottlenose dolphin ( T. t. gephyreus ), and

3984-541: The common bottlenose dolphin and other dolphin species, such as the humpback dolphin . The peak mating and calving seasons are in the spring and summer, although mating and calving occur throughout the year in some regions. The gestation period is about 12 months. Calves are between 0.84 and 1.5  m (2.8 and 4.9  ft ) long, and weigh between 9 and 21  kg (20 and 46  lb ). The calves are weaned between 1.5 and 2.0 years, but can remain with their mothers for up to 5 years. The interbirth interval for females

4067-442: The corals and sponges, suggesting that they might be used by the dolphins to treat skin infections. The species is not considered to be endangered ; its near-shore distribution, though, makes it vulnerable to environmental degradation, direct exploitation, and problems associated with local fisheries. The major predators of this species are typically sharks, and may include humans, killer whales ( Orcinus orca ), and stingrays. In

4150-564: The dolphin surface behaviour from traveling to milling, and changed their direction to travel away from the powerboat. When the powerboat left the area and its noise ceased, the dolphins returned to their preceding behaviour in the original direction. Another study in Shark Bay, Western Australia, on dolphin behavioural responses showed significant changes in the behaviour of targeted dolphins were found when compared with their behaviour before and after approaches by small watercraft. Dolphins in

4233-498: The dolphins' habitats and the whistles produced were compared. Ambient noise was recorded using a hydrophone located 10 m below the surface and whistles were recorded by using an underwater video system. The results showed dolphins produced whistles at varying frequencies with greater modulations when in habitats with less ambient noise, whereas habitats with greater ambient noise seem to cause dolphins to produce whistles of lower frequencies and fewer frequency modulations. Examination of

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4316-576: The early 1980s, many were deliberately killed in a Taiwanese driftnet fishery in the Arafura Sea, off northwestern Australia. Large-mesh nets set to protect bathers from sharks in South Africa and Australia have also resulted in a substantial number of deaths. Gillnets are also having an impact, and are a problem throughout most of the species' range. These small cetaceans are commonly found in captivity, causing conservation concerns, including

4399-420: The effects of removing the animals from their wild populations, survival of cetaceans during capture and transport and while in captivity, and the risks to wild populations and ecosystems of accidentally introducing alien species and spreading epizootic diseases, especially when animals have been transported over long distances and are held in sea pens. Bottlenose dolphins are the most common captive cetaceans on

4482-840: The effects of whale-watching boats on behavior, what these results mean for long-term population viability is not known. The Shark Bay population has been forecast to be relatively stable with little variation in mortality over time (Manlik et al. 2016). The Indo-Pacific bottlenose dolphin populations of the Arafura and the Timor Sea are listed on Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals ( CMS ). They are listed on Appendix II as they have an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements. The Indo-Pacific bottlenose dolphin

4565-463: The eyeball's lens serves to focus light, whereas in the in-air environment, the typically bright light serves to contract the specialized pupil, resulting in sharpness from a smaller aperture (similar to a pinhole camera ). By contrast, a bottlenose's sense of smell is poor, because its blowhole, the analog to the nose, is closed when underwater and it opens only for breathing. Like other toothed whales , it has no olfactory nerves or olfactory lobe in

4648-454: The fact that the Tursiops dolphins might consist of more than one species, as there is extensive variation in color and morphology along its range. In the past, most studies used morphology to evaluate differences between and within species, but in the late 20th century, combining morphological and molecular genetics allowed much greater insight into this previously intractable problem. Since

4731-493: The feeding ecology of Indo-Pacific bottlenose dolphins by analyzing the stomach contents of ones that got caught in the gillnet fisheries off Zanzibar , Tanzania . The prey items found in the stomach contents included 50 species of bony fish and three species of squid. From their results, the researchers concluded the most important prey group was fish, which accounted for 87% of the total number of prey items consumed and occurred in 24 of 26 stomachs examined. Cephalopods comprised

4814-648: The females are not in their estrous cycles and cannot produce young, suggesting they may mate for pleasure . The gestation period averages 12 months. Births can occur at any time of year, although peaks occur in warmer months. The young are born in shallow water, sometimes assisted by a (possibly male) "midwife", and usually only a single calf is born. Twins are possible, but rare. Newborn bottlenose dolphins are 0.8 to 1.4 m (2.6 to 4.6 ft) long and weigh 9 to 30 kg (20 to 66 lb), with Indo-Pacific bottlenose dolphin infants being generally smaller than common bottlenose dolphin infants. To accelerate nursing,

4897-600: 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 . Bottlenose dolphins have the third largest encephalization levels of any mammal on Earth (humans have the largest, followed by Northern Right whale dolphins ), sharing close ratios with those of humans and other cetaceans , while being twice as high of other great apes . This more than likely contributes to their high intelligence . Scientists have been long aware of

4980-537: The genital slit. The ability to stow their reproductive organs (especially in males) allows for maximum hydrodynamics. The breeding season produces significant physiological changes in males. At that time, the testes enlarge, enabling them to hold more sperm. Large amounts of sperm allow a male to wash away the previous suitor's sperm, while leaving some of his own for fertilization. Also, sperm concentration markedly increases. Having less sperm for out-of-season social mating means it wastes less. This suggests sperm production

5063-540: The genus Stenella , since it is more like the Atlantic spotted dolphin ( Stenella frontalis ) than the common bottlenose dolphin. However, more recent studies indicate that this is a consequence of reticulate evolution (such as past hybridization between Stenella and ancestral Tursiops ) and incomplete lineage sorting , and thus support T . truncatus and T. aduncus belonging to the same genus. Bottlenose dolphins have been known to hybridize with other dolphin species. Hybrids with Risso's dolphin occur both in

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5146-413: The late 1990s and early 2000s, most researchers acknowledged the existence of two species: the common bottlenose dolphin ( T. truncatus ), found in coastal and oceanic habitats of most tropical to temperate oceans, and the Indo-Pacific bottlenose dolphin ( T. aduncus ), that lives in coastal waters around India , northern Australia, South China, the Red Sea , and the eastern coast of Africa. In 2011,

5229-495: The low-traffic site showed a stronger and longer-lasting response than dolphins in the high-traffic site. These results are believed to show habituation of the dolphins to the vessels in a region of long-term vessel traffic. However, when compared to other studies in the same area, moderated responses, rather, were suggested to be because those individuals sensitive to vessel disturbance left the region before their study began. Although these studies do show statistical significance for

5312-419: The mother can eject milk from her mammary glands . The calf suckles for 18 months to up to 8 years, and continues to closely associate with its mother for several years after weaning. Females sexually mature at ages 5–13, males at ages 9–14. Females reproduce every two to six years. Reproduction is moderately seasonal (September–January), peaking from October to December. Calf loss between August and December

5395-432: The movement of a female for weeks at a time, waiting for her to become sexually receptive . These coalitions, also known as male reproductive alliances , will fight with other coalitions for control of females. Humans and bottlenose dolphins are the only species that share this type of "gang formation" habit as a form of cooperation. Mating occurs belly to belly. Dolphins have been observed engaging in intercourse when

5478-426: The old scientific data in the field combine data about the Indo-Pacific bottlenose dolphin and the common bottlenose dolphin into a single group, making it effectively useless in determining the structural differences between the two species. The IUCN lists the Indo-Pacific bottlenose dolphin as "near threatened" in their Red List of endangered species. Until 1998, all bottlenose dolphins were considered members of

5561-478: The other 13% of prey items and were found in 13 of the 26 stomachs. The remains of some crustaceans were also found; they hypothesize, however, they were consumed secondarily, since a number were found intact in the fish prey stomachs and therefore were not included in the diet analysis. Indo-Pacific bottlenose dolphins live in groups that can number in the hundreds, but groups of five to 15 dolphins are most common. In some parts of their range, they associate with

5644-564: The other hemisphere shuts down. The active hemisphere handles surfacing and breathing behavior. The daily sleeping cycle lasts for about 8 hours, in increments of minutes to hours. During the sleeping cycle, they remain near the surface, swimming slowly or "logging", and occasionally closing one eye. Both sexes have genital slits on the underside of their bodies. The male can retract and conceal his penis through his slit. The female's slit houses her vagina and anus. Females have two mammary slits, each housing one nipple , one on each side of

5727-441: The presence of their dependent calf. In all 19 cases, the mother dolphin changed the same signature whistle when the calf was present, by reaching a higher frequency, or using a wider frequency range. Similarly, humans use higher fundamental frequencies and a wider pitch range to inflect child–directed speech (CDS). This has rarely been discovered in other species. The researchers stated that CDS benefits for humans are cueing

5810-495: The results suggest communication signals are adaptive and are selected to avoid the masking of signals and the decrease of higher-frequency signals. They concluded ambient noise has the potential to drive the variation in whistles of Indo-Pacific bottlenose dolphin populations. Small, motorized vessels have increased as a source of anthropogenic noise due to the rise in popularity of wildlife viewing such as whale watching. Another study showed powerboat approaches within 100 m altered

5893-617: The sensitivity of the sound receptor.) The interclick interval also decreases as the animal nears the target. Evidently, the dolphin waits for each click's echo before clicking again. Echolocation details, such as signal strength, spectral qualities, and discrimination, are well understood by researchers. Bottlenose dolphins are also able to extract shape information, suggesting they are able to form an "echoic image" or sound picture of their targets. They also have electroreception . The calves are born with two slender rows of whiskers along their snout, which fall off soon after birth, leaving behind

5976-411: The shape, size, speed, distance, and location of the object. To hear the returning echo, they have two small ear openings behind the eyes, but most sound waves are transmitted to the inner ear through the lower jaw. As the object of interest is approached, the echo becomes booming, and the dolphins adjust by decreasing the intensity of the emitted sounds. (This contrasts with bats and sonar, which reduce

6059-406: The single species T. truncatus . But in that year, the Indo-Pacific bottlenose dolphin was recognized as a separate species. Both species are thought to have split during the mid- Pleistocene , about 1 million years ago. Some evidence shows the Indo-Pacific bottlenose dolphin may actually be more closely related to certain dolphin species in the genera Stenella and Delphinus , especially

6142-468: The social strategies of elephants and chimpanzees. Bottlenose dolphins studied by Bottlenose Dolphin Research Institute researchers off the island of Sardinia show random social behavior while feeding, and their social behavior does not depend on feeding activity. In Sardinia, the presence of a floating marine fin-fish farm has been linked to a change in bottlenose dolphin distribution as

6225-526: The strong personal behavior among male calves is about bond formation and benefits the species in an evolutionary context. She cites studies showing these dolphins as adults are inseparable, and that early bonds aid protection, as well as in locating females. Female bottlenose dolphins have to expend additional energy in carrying out parental care, e.g. , infant-carrying behavior. Dolphins do not physically hold their infants but line up in an echelon position with infants swimming beside them. This position creates

6308-486: The tail) and dorsal fin are formed of dense connective tissue and do not contain bone or muscle . The dorsal fin usually shows phenotypic variations that help discriminate among populations. The animal propels itself by moving the flukes up and down. The pectoral flippers (at the sides of the body) are for steering; they contain bones homologous to the forelimbs of land mammals. A bottlenose dolphin discovered in Japan has two additional pectoral fins, or "hind legs", at

6391-649: The tail, about the size of a human's pair of hands. Scientists believe a mutation caused the ancient trait to reassert itself as a form of atavism . In colder waters, they have more body fat and blood, and are more suited to deeper diving. Typically, 18%–20% of their body weight is blubber. Most research in this area has been restricted to the North Atlantic Ocean . Bottlenose dolphins typically swim at 5 to 11 km/h (1.4 to 3.1 m/s), but are capable of bursts of up to 29 to 35 km/h (8.1 to 9.7 m/s). The higher speeds can only be sustained for

6474-481: The taste of their urine in the water. Bottlenose dolphins communicate through burst pulsed sounds, whistles, and body language. Examples of body language include leaping out of the water, snapping jaws, slapping the tail on the surface and butting heads. Sounds and gestures help keep track of other dolphins in the group, and alert other dolphins to danger and nearby food. Lacking vocal cords , they produce sounds using six air sacs near their blow hole. Each animal has

6557-427: The two ecotypes of the common bottlenose dolphin within the western North Atlantic are represented by the shallower water or coastal ecotype and the more offshore ecotype. Their ranges overlap, but they have been shown to be genetically distinct. In 2022, Costa et al. established morphologic, genetic, and evolutionary divergence between the two ecotypes in the western North Atlantic, resurrecting Tursiops erebennus for

6640-437: The upper part of their bodies vertically out of the water, and propel themselves along the surface with powerful tail movements. Tail-walking mostly arises via human training in dolphinaria. In the 1980s, a female from the local population was kept at a local dolphinarium for three weeks, and the scientist suggests she copied the tail-walking behavior from other dolphins. Two other wild adult female dolphins copied it from her, and

6723-451: The whistles) are used "to avoid physical aggression in situations of high excitement", such as when they are competing for the same piece of food, for example. The dolphins emit these strident sounds when in the presence of other individuals moving towards the same prey. The "least dominant" one soon moves away to avoid confrontation. Other communication uses about 30 distinguishable sounds, and although famously proposed by John C. Lilly in

6806-615: The wild and in captivity. The best known hybrid is the wholphin , a false killer whale -bottlenose dolphin hybrid. The wholphin is fertile, and two currently live at the Sea Life Park in Hawaii. The first was born in 1985 to a female bottlenose. Wholphins also exist in the wild. In captivity, a bottlenose dolphin and a rough-toothed dolphin hybridized. A common dolphin -bottlenose dolphin hybrid born in captivity lives at SeaWorld California. Other hybrids live in captivity around

6889-733: The world and in the wild, such as a bottlenose dolphin-Atlantic spotted dolphin hybrid. Bottlenose dolphins appeared during the Miocene . Known fossil species include Tursiops osennae (late Miocene to early Pliocene ) from the Piacenzian coastal mudstone, and Tursiops miocaenus (Miocene) from the Burdigalian marine sandstone, all in Italy. The bottlenose dolphin weighs an average of 300 kg (660 lb), but can range from 150 and 650 kg (330 and 1,430 lb). It can reach

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