The Marine Mammal Protection Act ( MMPA ) was the first act of the United States Congress to call specifically for an ecosystem approach to wildlife management.
104-437: The spinner dolphin ( Stenella longirostris ) is a small dolphin found in off-shore tropical waters around the world. It is famous for its acrobatic displays in which it rotates around its longitudinal axis as it leaps through the air. It is a member of the family Delphinidae of toothed whales . The spinner dolphin is sometimes referred to as the long-snouted dolphin , particularly in older texts, to distinguish it from
208-830: A basis for importing fish and fish products from nations engaged in harvesting yellowfin tuna with purse seines and other commercial fishing technology, as well as authorized appropriations for agency activities through FY 1988. Amended in 1988 Amended in 1994 Under the MMPA amended in 1994, in Section 119, NMFS and FWS was authorized to form the cooperative agreements ( co-management plan) with Alaska Native Organizations (ANOs) . This allows indigenous tribal government can engage in their territorial marine mammal protection and subsistence taking issues through individual co-management agreements which can be established with NOAA, USFWS, MMC, or other MMPA-affiliated agencies. Co-management
312-470: A dark band runs from the eye to the flipper, bordered above by a thin, light line. However, the spinner dolphin has more geographic variation in form and coloration than other cetaceans. In the open waters of eastern Pacific, dolphins have relatively small skulls with short rostra. A dwarf form of spinner dolphin occurs around southeast Asia. In these same subspecies, a dark dorsal cape dims their tripartite color patterns. Further offshore, subspecies tend to have
416-433: A few, such as the orca, feed on large mammals such as seals. Male dolphins typically mate with multiple females every year, but females only mate every two to three years. Calves are typically born in the spring and summer months and females bear all the responsibility for raising them. Mothers of some species fast and nurse their young for a relatively long period of time. Dolphins produce a variety of vocalizations, usually in
520-425: A fully asleep state where both eyes are closed and there is no response to mild external stimuli. In this case, respiration is automatic; a tail kick reflex keeps the blowhole above the water if necessary. Anesthetized dolphins initially show a tail kick reflex. Though a similar state has been observed with wild sperm whales , it is not known if dolphins in the wild reach this state. The Indus river dolphin has
624-465: A male dolphin is, the more likely his body is to be covered with bite scars. Male dolphins can get into disputes over companions and females. Acts of aggression can become so intense that targeted dolphins sometimes go into exile after losing a fight. Male bottlenose dolphins have been known to engage in infanticide . Dolphins have also been known to kill porpoises (porpicide) for reasons which are not fully understood, as porpoises generally do not share
728-419: A more limited capacity for color vision than most mammals. Most dolphins have slightly flattened eyeballs, enlarged pupils (which shrink as they surface to prevent damage), slightly flattened corneas and a tapetum lucidum (eye tissue behind the retina); these adaptations allow for large amounts of light to pass through the eye and, therefore, a very clear image of the surrounding area. They also have glands on
832-452: A paler and less far-reaching cape. In certain subspecies, some males may have upright fins that slant forward. Some populations of spinner dolphin found in the eastern Pacific have backwards-facing dorsal fins, and males can have dorsal humps and upturned caudal flukes . The spinner dolphin lives in nearly all tropical and subtropical waters between 40°N and 40°S . The species primarily inhabits coastal waters, islands, or banks. However, in
936-573: A promiscuous mating system, with individuals changing partners for up to some weeks. A dozen adult males may gather into coalitions. Vocalizations of spinner dolphins include whistles, which may be used to organize the school, burst-pulse signals, and echolocation clicks. The spinner dolphin has a 10-month gestation period, and mothers nurse their young for one to two years. Females are sexually mature at four to seven years, with three-year calving intervals, while males are sexually mature at seven to 10 years. Spinner dolphins live for about 20-25 years. Breeding
1040-573: A short timespan. The gestation period varies with species; for the small tucuxi dolphin , this period is around 11 to 12 months, while for the orca, the gestation period is around 17 months. Typically dolphins give birth to a single calf, which is, unlike most other mammals, born tail first in most cases. They usually become sexually active at a young age, even before reaching sexual maturity . The age of sexual maturity varies by species and sex. Dolphins are known to display non-reproductive sexual behavior , engaging in masturbation , stimulation of
1144-419: A sleep method that is different from that of other dolphin species. Living in water with strong currents and potentially dangerous floating debris, it must swim continuously to avoid injury. As a result, this species sleeps in very short bursts which last between 4 and 60 seconds. There are various feeding methods among and within species, some apparently exclusive to a single population. Fish and squid are
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#17327975837431248-614: A specified activity other than commercial fishing in a specified geographic area. Directed permits are required for any proposed marine mammal scientific research activity that involves taking marine mammals. Applications for such permits are reviewed and issued the Service's Division of Management Authority, through the International Affairs office. This office also houses the Division of International Conservation, which
1352-411: A thin layer of blubber, which develops at different paces depending on the habitat. Dolphins have a two-chambered stomach that is similar in structure to terrestrial carnivores. They have fundic and pyloric chambers. Dolphins' reproductive organs are located inside the body, with genital slits on the ventral (belly) side. Males have two slits, one concealing the penis and one further behind for
1456-447: Is adapted for both air and water; it is so well developed that some can survive even if they are blind. Some species are well adapted for diving to great depths. They have a layer of fat, or blubber , under the skin to keep warm in the cold water. Dolphins are widespread. Most species prefer the warm waters of the tropic zones, but some, such as the right whale dolphin , prefer colder climates. Dolphins feed largely on fish and squid, but
1560-403: Is also known as kinesthesia, is the body's ability to sense its location, movements and actions. Dolphins are sensitive to vibrations and small pressure changes. Blood vessels and nerve endings can be found within the dermis. There is a plexus of parallel running arteries and veins in the dorsal fin, fluke, and flippers. The blubber manipulates the blood vessels to help the dolphin stay warm. When
1664-573: Is called a school or a pod . Male dolphins are called bulls , females are called cows and young dolphins are called calves . In 1933, three hybrid dolphins beached off the Irish coast; they were hybrids between Risso's and bottlenose dolphins. This mating was later repeated in captivity, producing a hybrid calf. In captivity, a bottlenose and a rough-toothed dolphin produced hybrid offspring. A common-bottlenose hybrid lives at SeaWorld California. Other dolphin hybrids live in captivity around
1768-746: Is covered by Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region ( Pacific Cetaceans MoU ) and the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia ( Western African Aquatic Mammals MoU ). Spinner dolphins are susceptible to disease and two of the recorded diseases within them are toxoplasmosis and cetacean morbillivirus. The number of cases reported however
1872-1093: Is developed with a team involving representatives from fishing industry, management councils, governmental agencies, scientific community, and conservation organization. The consensus from the representatives is then submitted to NOAA for review then through the public comment. As the Plan is finalized, NOAA has the duty to monitor its implementation with the team. Yet, the Plans are uneven or unstandardized in practice to meet its statutory requirement. Successful plans are often based upon mandated, quantitative metrics, and consistent monitoring programs. Congress found that: all species and population stocks of marine mammals are, or may be, in danger of extinction or depletion due to human activities; these mammals should not be permitted to diminish below their optimum sustainable population; measures should be taken immediately to replenish any of these mammals that have diminished below that level, and efforts should be made to protect essential habitats; there
1976-636: Is directly responsible for coordinating international activities for marine mammal species found in both U.S. and International waters, or are absent from U.S. waters. Marine mammal species inhabiting both U.S. and International waters include the West Indian manatee , sea otter , polar bear , and Pacific walrus . Species not present in U.S. waters include the West African and Amazonian manatee , dugong , Atlantic walrus , and marine otter . In efforts to conserve and manage marine mammal species,
2080-468: Is fairly low in the species. Spinner dolphins in Hawaii receive multiple daily visits to their near-shore resting grounds, with boats taking people out daily to snorkel and interact with the local dolphin population. Such activities are increasingly coming under criticism on the grounds of possible harm to the dolphins, and efforts are being made both to educate the public in order to minimise human impact on
2184-408: 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, judgment, and theory of mind. Cetacean spindle neurons are found in areas of the brain that are analogous to where they are found in humans, suggesting that they perform a similar function. Brain size was previously considered a major indicator of
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#17327975837432288-536: Is inadequate knowledge of the ecology and population dynamics of these mammals; negotiations should be undertaken immediately to encourage international arrangements for research and conservation of these mammals. Congress declared that marine mammals are resources of great international significance (aesthetic, recreational and economic), and should be protected and encouraged to develop to the greatest extent feasible commensurate with sound policies of resource management. The primary management objective should be to maintain
2392-701: Is mostly transferred by mothers to daughters, unlike simian primates, where knowledge is generally passed on to both sexes. Using sponges as mouth protection is a learned behavior. Another learned behavior was discovered among river dolphins in Brazil, where some male dolphins use weeds and sticks as part of a sexual display. Forms of care-giving between fellows and even for members of different species (see Moko (dolphin) ) are recorded in various species – such as trying to save weakened fellows or female pilot whales holding up dead calves for long periods. Dolphins engage in acts of aggression towards each other. The older
2496-433: Is much less definitive than when used for primates, because primates can touch the mark or the mirror, while cetaceans cannot, making their alleged self-recognition behavior less certain. Skeptics argue that behaviors that are said to identify self-awareness resemble existing social behaviors, and so researchers could be misinterpreting self-awareness for social responses to another individual. The researchers counter-argue that
2600-545: Is no great difference between the outer and inner environments. Instead of sound passing through the outer ear to the middle ear, dolphins receive sound through the throat, from which it passes through a low-impedance fat-filled cavity to the inner ear. The ear is acoustically isolated from the skull by air-filled sinus pockets, which allow for greater directional hearing underwater. Dolphins generate sounds independently of respiration using recycled air that passes through air sacs and phonic (alternatively monkey) lips. Integral to
2704-620: Is not rigid; interchange is common. They establish strong social bonds, and will stay with injured or ill members, helping them to breathe by bringing them to the surface if needed. This altruism does not appear to be limited to their own species. The dolphin Moko in New Zealand has been observed guiding a female pygmy sperm whale together with her calf out of shallow water where they had stranded several times. They have also been seen protecting swimmers from sharks by swimming circles around
2808-558: Is seasonal, more so in certain regions than others. Although most spinner dolphins are found in the deeper waters offshore of the islands, the rest of the Hawaiʻi population has a more coastal distribution. During daytime hours, the island-associated stocks of Hawaiian spinner dolphins seek sanctuary in nearshore waters, where they return to certain areas to socialize, rest, and nurture their young. Spinner dolphins are known for their acrobatics and aerial behaviors. A spinner dolphin comes out of
2912-736: Is the bottlenose dolphin , while there are around 60 orcas in captivity . The name is originally from Greek δελφίς ( delphís ), "dolphin", which was related to the Greek δελφύς ( delphus ), "womb". The animal's name can therefore be interpreted as meaning "a 'fish' with a womb". The name was transmitted via the Latin delphinus (the romanization of the later Greek δελφῖνος – delphinos ), which in Medieval Latin became dolfinus and in Old French daulphin , which reintroduced
3016-460: Is the mirror test in which a mirror is introduced to an animal, and the animal is then marked with a temporary dye. If the animal then goes to the mirror in order to view the mark, it has exhibited strong evidence of self-awareness. Some disagree with these findings, arguing that the results of these tests are open to human interpretation and susceptible to the Clever Hans effect. This test
3120-432: Is to remove ectoparasites such as remoras. Dolphins may also make nose-outs, tail slaps, flips, head slaps, "salmon leaps", and side and back slaps. The protected status of spinner dolphins are CITES Appendix II and Marine Mammal Protection Act (MMPA) protected throughout its range as well as MMPA depleted in its eastern stock. Tens of thousands of spinner dolphins, mostly eastern and white-bellied varieties, were killed in
3224-411: Is viewed as the practice of indigenous sovereignty and self-determination. Co-management under Section 119 includes the following activities: Alaska Nanuuq Commission (ANC) represents tribes for polar bears management with USFWS. In this partnership, the subsistence take of polar bear is legal according to MMPA, yet the prohibition is placed on taking females with cubs and harassment. Along with
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3328-773: The Caribbean Sea ; however, this species is most prevalent near Florida (the Florida subspecies) and Puerto Rico (the Antillean subspecies). The Service's Jacksonville Field Office manages the Florida manatee , while the Boqueron Field Office manages the Antillean manatee . The polar bear, southern sea otter, marine otter, all three species of manatees, and the dugong are also concurrently listed under
3432-586: The Endangered Species Act (ESA). Amendments enacted in 1981 established conditions for permits to be granted to take marine mammals "incidentally" in the course of commercial fishing. In addition, the amendments provided additional conditions and procedures for transferring management authority to the States, and authorized appropriations through FY 1984. Policies created in 1982 The 1984 amendments established conditions to be satisfied as
3536-742: The International Convention for the Regulation of Whaling , the Whaling Convention Act of 1949, the Interim Convention on the Conservation of North Pacific Fur Seals, and the Fur Seal Act of 1966.” The MMC is also responsible for the review of the research programs conducted for the purpose of the MMPA as well as authorizing permits for the purpose of research, conservation or public display. If
3640-484: The NOAA , the U.S. Fish and Wildlife Services conduct stock assessments of marine mammal populations under their jurisdiction which include walrus , manatees , sea otters , and polar bears . They are also responsible for the creation and implementation of conservation plans which often occur in collaboration with industries which can potentially impact marine mammal populations of particular concern. The MMPA prohibits
3744-609: The ancient Roman author and natural philosopher Pliny the Elder . A modern human-dolphin partnership currently operates in Laguna , Santa Catarina, Brazil. Here, dolphins drive fish towards fishermen waiting along the shore and signal the men to cast their nets. The dolphins' reward is the fish that escape the nets. Marine Mammal Protection Act MMPA was signed into law on October 21, 1972, by President Richard Nixon and took effect 60 days later on December 21, 1972. It prohibits
3848-419: The anus . Females have one genital slit, housing the vagina and the anus, with a mammary slit on either side. The integumentary system is an organ system mostly consisting of skin, hair, nails and endocrine glands. The skin of dolphins is specialized to satisfy specific requirements, including protection, fat storage, heat regulation, and sensory perception. The skin of a dolphin is made up of two parts:
3952-485: The artiodactyl order (even-toed ungulates). They are related to the Indohyus , an extinct chevrotain -like ungulate, from which they split approximately 48 million years ago. The primitive cetaceans, or archaeocetes , first took to the sea approximately 49 million years ago and became fully aquatic by 5–10 million years later. Archaeoceti is a parvorder comprising ancient whales. These ancient whales are
4056-432: The mahi-mahi fish is called the dolphinfish. In common usage, the term whale is used only for the larger cetacean species, while the smaller ones with a beaked or longer nose are considered dolphins. The name dolphin is used casually as a synonym for bottlenose dolphin , the most common and familiar species of dolphin. There are six species of dolphins commonly thought of as whales, collectively known as blackfish :
4160-506: The orca , the melon-headed whale , the pygmy killer whale , the false killer whale , and the two species of pilot whales , all of which are classified under the family Delphinidae and qualify as dolphins. Although the terms dolphin and porpoise are sometimes used interchangeably, porpoise usually refers to the Phocoenidae family, which have a shorter beak and spade-shaped teeth and differ in their behavior. A group of dolphins
4264-418: The ph into the word dolphin . The term mereswine ("sea pig") is also used. The term dolphin can be used to refer to most species in the family Delphinidae (oceanic dolphins) and the river dolphin families of Iniidae (South American river dolphins), Pontoporiidae ( La Plata dolphin ), Lipotidae (Yangtze river dolphin) and Platanistidae (Ganges river dolphin and Indus river dolphin). Meanwhile,
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4368-462: The "taking" of marine mammals , and enacts a moratorium on the import, export, and sale of any marine mammal, along with any marine mammal part or product within the United States . The Act defines "take" as "the act of hunting , killing, capture, and/or harassment of any marine mammal; or, the attempt at such." The MMPA defines harassment as "any act of pursuit, torment or annoyance which has
4472-607: The 1.7-metre-long (5 ft 7 in) and 50-kilogram (110-pound) Maui's dolphin to the 9.5 m (31 ft) and 10-tonne (11-short-ton) orca . Various species of dolphins exhibit sexual dimorphism where the males are larger than females. They have streamlined bodies and two limbs that are modified into flippers. Though not quite as flexible as seals , they are faster; some dolphins can briefly travel at speeds of 29 kilometres per hour (18 mph) or leap about 9 metres (30 ft). Dolphins use their conical teeth to capture fast-moving prey . They have well-developed hearing which
4576-537: The 30 years after purse seine fishing for tuna began in the 1950s. The process killed probably half of all eastern spinner dolphins. They have also been contaminated by pollutants such as DDT and PCBs . Spinner dolphins, as with other species affected by ETP tuna purse-seine fishing, are managed nationally by the coastal countries and internationally by the IATTC . The IATTC has imposed annual stock mortality limits on each purse seine and promulgated regulations regarding
4680-573: The 9.5 m (31 ft 2 in) and 10 t (11 short tons) orca . Overall, they tend to be dwarfed by other Cetartiodactyls . Several species have female-biased sexual dimorphism, with the females being larger than the males. Dolphins have conical teeth, as opposed to porpoises ' spade-shaped teeth. These conical teeth are used to catch swift prey such as fish, squid or large mammals, such as seals. Breathing involves expelling stale air from their blowhole , in an upward blast, which may be visible in cold air, followed by inhaling fresh air into
4784-468: The Latin word for "long-beaked." Spinner dolphins are small cetaceans with a slim build. Adults are typically 129–235 cm long and reach a body mass of 23–79 kg. This species has an elongated rostrum and a triangular or subtriangular dorsal fin . Spinner dolphins generally have tripartite color patterns. The dorsal area is dark gray, the sides light gray, and the underside pale gray or white. Also,
4888-602: The MMC finds that the current conservation efforts are shown to be ineffective in protecting species identified under the MMPA, they are responsible for effectively communicating with federal officials such as the Secretaries of State , Commerce or the Interior the recommended measures needed to be taken to ensure the effectiveness of the MMPA and the protection of marine mammals under this act. These recommendations can come in
4992-577: The MMPA. The specific information that is included in all stock assessments are the geographic range of the stock being studied, current trends and productivity rates for the stock, potential biological removal levels which is defined under the MMPA as “the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population”, an estimation of mortality and injury rate caused by humans, potential threats to conservation efforts and current status of
5096-492: The MMPA. Coordination between these three federal agencies is necessary in order to provide the best management practices for marine mammals. Under the MMPA, the Service is responsible for ensuring the protection of sea otters and marine otters, walruses , polar bears , three species of manatees , and dugongs . NOAA was given responsibility to conserve and manage pinnipeds including seals and sea lions and cetaceans such as whales and dolphins . The NOAA enforces
5200-895: The Marine Mammal Protection Act through the implementation and enforcement of various policies and regulations to properly manage marine mammal populations. The NOAA does this through the identification of violations of the MMPA, coordinating efforts to aid stranded and entangled mammals, and conduct proper rehabilitation and release of injured marine mammals. The NOAA is also responsible for providing stock assessment reports on marine mammals under their jurisdiction which includes whales , dolphins , porpoises , seals , and sea lions . Stock assessment reports serve to identify trends in marine mammal populations, identify potential threats to said population, and whether current conservation efforts are effective and if adjustments need to be made to ensure effective enforcement of
5304-467: The Service has appointed field staff dedicated to working with partners to conduct population censuses, assess population health, develop and implement conservation plans, promulgate regulations, and create cooperative relationships internationally. Various Marine Mammal Management offices are located on either coast. The Service's Marine Mammal Management office in Anchorage, Alaska is responsible for
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#17327975837435408-600: The US domestic standards. Yet it is difficult to expect this comparability from all exporting countries due to lack of fisheries records on bycatches and standardized protective measures which is causing unintentional harms. The Act emphasizes the recovery and prevention of the depletion of strategic marine mammal stocks. Under Section 118, Take Reduction Plan aims within six months of implementation to reduce incidental mortality and severe injury from fishery and approach zero mortality rate in five years. The Plan includes: The plan
5512-401: The animal with an idea on an object's shape and size, though how exactly this works is not yet understood. The small hairs on the rostrum of the boto (river dolphins of South America) are believed to function as a tactile sense , possibly to compensate for the boto's poor eyesight. A dolphin eye is relatively small for its size, yet they do retain a good degree of eyesight. As well as this,
5616-674: The behaviors shown are evidence of self-awareness, as they are very different from normal responses to another individual. Whereas apes can merely touch the mark on themselves with their fingers, cetaceans show less definitive behavior of self-awareness; they can only twist and turn themselves to observe the mark. In 1995, Marten and Psarakos used television to test dolphin self-awareness. They showed dolphins real-time video of themselves, video of another dolphin and recorded footage. 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
5720-527: The body and to form specialized locomotor structures such as the dorsal fin, propulsive fluke blades and caudal keels. There are many nerve endings that resemble small, onion-like configurations that are present in the superficial portion of the dermis. Mechanoreceptors are found within the interlocks of the epidermis with dermal ridges. There are nerve fibers in the dermis that extend to the epidermis. These nerve endings are known to be highly proprioceptive , which explains sensory perception. Proprioception, which
5824-485: The closest living relatives of cetaceans are the hippopotamuses ; these share a semi-aquatic ancestor that branched off from other artiodactyls some 60 million years ago. Around 40 million years ago, a common ancestor between the two branched off into cetacea and anthracotheres ; anthracotheres became extinct at the end of the Pleistocene two-and-a-half million years ago, eventually leaving only one surviving lineage:
5928-557: The co-management, Alaska Scientific Review Group is set up, with indigenous entities involved, to advise stock assessment and revise method for assessment. Alaska Beluga Whale Committee (ABWC) was founded in 1988 to manage beluga subsistence hunting in Alaska. After the MMPA amended, ABWC starts to develop a co-management plan with National Marine Fisheries Service (NMFS) aiming to become an "umbrella organization concerned with statewide, national and international affairs. " With
6032-595: The dolphins as they tried to escape. Dolphin A dolphin is an aquatic mammal in the clade Odontoceti ( toothed whale ). Dolphins belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins ), Iniidae (the New World river dolphins), Pontoporiidae (the brackish dolphins), and possibly extinct Lipotidae (baiji or Chinese river dolphin). There are 40 extant species named as dolphins. Dolphins range in size from
6136-509: The dolphins, and to bring in regulations to govern these activities. In 2023, 33 swimmers were arrested for reportedly harassing dolphins off the coast of the Big Island of Hawaii. The swimmers reportedly broke federal law by swimming within 45 meters (50 yards) of the dolphins. The ban went into effect in 2021 due to dolphins not getting enough rest during the day to forage for food at night. The swimmers were caught by drone footage pursuing
6240-402: The dorsal fin, flukes, and flippers. These thermal windows are a good way for dolphins to get rid of excess heat if overheating. Additionally in order to conserve heat, dolphins use countercurrent heat exchange. Blood flows in different directions in order for heat to transfer across membranes. Heat from warm blood leaving the heart will heat up the cold blood that is headed back to the heart from
6344-606: The eastern tropical Pacific, spinner dolphins live far from shore. Spinner dolphins may use different habitats depending on the season. The spinner dolphin feeds mainly on small mesopelagic fish, squids, and sergestid shrimps, and will dive 200–300 m to feed on them. Spinner dolphins of Hawaii are nocturnal feeders and forage in deep scattering layers, which contain many species. The dwarf spinner dolphin may feed mostly on benthic fish in reefs and shallow water. Off Oahu, Hawaii, spinner dolphins forage at night and cooperatively herd their prey into highly dense patches. They swim around
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#17327975837436448-413: The epidermal layer. The thickness of a dolphin's epidermis varies, depending on species and age. Blubber is found within the dermis and subcutis layer. The dermis blends gradually with the adipose layer, which is known as fat, because the fat may extend up to the epidermis border and collagen fiber bundles extend throughout the whole subcutaneous blubber which is fat found under the skin. The thickness of
6552-411: The epidermis and the blubber, which consists of two layers including the dermis and subcutis. The dolphin's skin is known to have a smooth rubber texture and is without hair and glands, except mammary glands. At birth, a newborn dolphin has hairs lined up in a single band on both sides of the rostrum, which is their jaw, and usually has a total length of 16–17 cm . The epidermis is characterized by
6656-511: The extremities, meaning that the heart always has warm blood and it decreases the heat lost to the water in those thermal windows. Dolphins have two pectoral flippers, each containing four digits, a boneless dorsal fin for stability, and a fluke for propulsion. Although dolphins do not possess external hind limbs, some possess discrete rudimentary appendages, which may contain feet and digits. Orcas are fast swimmers in comparison to seals which typically cruise at 9–28 km/h (5.6–17.4 mph);
6760-484: The eyelids and outer corneal layer that act as protection for the cornea. The olfactory lobes and nerve are absent in dolphins, suggesting that they have no sense of smell. Dolphins are not thought to have a good sense of taste, as their taste buds are atrophied or missing altogether. Some have preferences for different kinds of fish, indicating some ability to taste. Dolphins are known to teach, learn, cooperate, scheme, and grieve. The neocortex of many species
6864-511: The eyes of a dolphin are placed on the sides of its head, so their vision consists of two fields, rather than a binocular view like humans have. When dolphins surface, their lens and cornea correct the nearsightedness that results from the water's refraction of light. Their eyes contain both rod and cone cells, meaning they can see in both dim and bright light, but they have far more rod cells than they do cone cells. They lack short wavelength sensitive visual pigments in their cone cells, indicating
6968-447: The females by their side by means of both physical aggression and intimidation, to increase their chances of reproductive success. Generally, dolphins sleep with only one brain hemisphere in slow-wave sleep at a time, thus maintaining enough consciousness to breathe and to watch for possible predators and other threats. Sleep stages earlier in sleep can occur simultaneously in both hemispheres. In captivity, dolphins seemingly enter
7072-414: The form of clicks and whistles. Dolphins are sometimes hunted in places such as Japan, in an activity known as dolphin drive hunting . Besides drive hunting, they also face threats from bycatch , habitat loss, and marine pollution . Dolphins have been depicted in various cultures worldwide. Dolphins are sometimes kept in captivity and trained to perform tricks. The most common dolphin species in captivity
7176-504: The form of implementation of international agreements, revisions to the endangered and threatened species list as deemed appropriate under the Endangered Species Act of 1973 , and provisions that may need to be made to the MMPA. The U.S. Fish and Wildlife Services are responsible for managing the take through the use of permits and other authorization as well as financially supporting efforts to help marine mammals that fall victim to stranding and relevant research efforts. Similar to
7280-526: The founding from NMFS, ABWC focus on facilitating scientific communication for the public, harvest monitoring, beluga tracking, aerial survey, genetics-based stock studies. The regional groups of ABWC are designate to "develop local management plans, hunting guide-lines and means of enforcement. " The Marine Mammal Protection Act has conservation benefits beyond US boundaries. The Act requires imported fisheries products to minimize incidental mortality and severe injury of marine mammals aligning to
7384-539: The genital area of other individuals using the rostrum or flippers, and homosexual contact . Various species of dolphin have been known to engage in sexual behavior including copulation with dolphins of other species, and occasionally exhibit sexual behavior towards other animals , including humans. Sexual encounters may be violent, with male bottlenose dolphins sometimes showing aggressive behavior towards both females and other males. Male dolphins may also work together and attempt to herd females in estrus , keeping
7488-443: The hearing set-up that channeled vibrations from the jaw to the earbone which occurred with Ambulocetus 49 million years ago, a streamlining of the body and the growth of flukes on the tail which occurred around 43 million years ago with Protocetus , the migration of the nasal openings toward the top of the cranium and the modification of the forelimbs into flippers which occurred with Basilosaurus 35 million years ago, and
7592-432: The heart, brain and other organs. Their hemoglobin and myoglobin store oxygen in body tissues, and they have twice as much myoglobin as hemoglobin. [REDACTED] A dolphin ear has specific adaptations to the marine environment. In humans, the middle ear works as an impedance equalizer between the outside air's low impedance and the cochlear fluid's high impedance. In dolphins, and other marine mammals, there
7696-563: 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 at approximately the ⅔ or ¾ 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. Orcas have
7800-403: The lack of keratin and by a prominent intertwine of epidermal rete pegs and long dermal papillae. The epidermal rete pegs are the epithelial extensions that project into the underlying connective tissue in both skin and mucous membranes. The dermal papillae are finger-like projections that help adhesion between the epidermal and dermal layers, as well as providing a larger surface area to nourish
7904-613: The lips are oil-filled organs called dorsal bursae that have been suggested to be homologous to the sperm whale's spermaceti organ. High-frequency clicks pass through the sound-modifying organs of the extramandibular fat body, intramandibular fat body and the melon . This melon consists of fat, and the skull of any such creature containing a melon will have a large depression. This allows dolphins to use echolocation for orientation. Though most dolphins do not have hair, they do have hair follicles that may perform some sensory function. Beyond locating an object, echolocation also provides
8008-408: The lungs. Dolphins have rather small, unidentifiable spouts. All dolphins have a thick layer of blubber , thickness varying on climate. This blubber can help with buoyancy, protection to some extent as predators would have a hard time getting through a thick layer of fat, and energy for leaner times; the primary usage for blubber is insulation from the harsh climate. Calves, generally, are born with
8112-411: The main food, but the false killer whale and the orca also feed on other marine mammals. Orcas on occasion also hunt whale species larger than themselves. Different breeds of dolphins vary widely in the number of teeth they possess. The orca usually carries 40–56 teeth while the popular bottlenose dolphin has anywhere from 72 to 116 conical teeth and its smaller cousin the common dolphin has 188–268 teeth:
8216-676: The management and conservation of polar bears , Pacific walruses , and northern sea otters in Alaska. Northern sea otters present in Washington state are managed by the Western Washington Field Office, while southern sea otters residing in California are managed by the Ventura Field Office. West Indian manatee populations extend from Texas to Rhode Island , and are also present in
8320-437: The mirror test. Some researchers have argued that evidence for self-awareness has not been convincingly demonstrated. Dolphins are highly social animals, often living in pods of up to a dozen individuals, though pod sizes and structures vary greatly between species and locations. In places with a high abundance of food, pods can merge temporarily, forming a superpod ; such groupings may exceed 1,000 dolphins. Membership in pods
8424-410: The number of teeth that an individual carries varies widely between within a single species. Hybrids between common and bottlenose bred in captivity had a number of teeth intermediate between that of their parents. One common feeding method 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
8528-690: The orca, in comparison, can travel at speeds up to 55.5 km/h (34.5 mph). A study of a Pacific white-sided dolphin in an aquarium found fast burst acceleration, with the individual being able with 5 strokes (2.5 fluke beats) to go from 5.0 m s-1 to 8.7 m s-1 in 0.7 seconds. The fusing of the neck vertebrae, while increasing stability when swimming at high speeds, decreases flexibility, which means most dolphins are unable to turn their heads. River dolphins have non-fused neck vertebrae and can turn their heads up to 90°. Dolphins swim by moving their fluke and rear body vertically, while their flippers are mainly used for steering. Some species porpoise out of
8632-402: The potential to either: a. injure a marine mammal in the wild, or b. disturb a marine mammal by causing disruption of behavioral patterns, which includes, but is not limited to, migration, breathing, nursing, breeding, feeding, or sheltering." The MMPA provides for enforcement of its prohibitions, and for the issuance of regulations to implement its legislative goals. Authority to manage the MMPA
8736-425: The predecessors of modern whales, stretching back to their first ancestor that spent their lives near (rarely in) the water. Likewise, the archaeocetes can be anywhere from near fully terrestrial, to semi-aquatic to fully aquatic, but what defines an archaeocete is the presence of visible legs or asymmetrical teeth. Their features became adapted for living in the marine environment . Major anatomical changes include
8840-474: The prey in a circle and a pair may swim through the circle to make a catch. Spinner dolphins are in turn preyed on by sharks. Other possible predators include the killer whale , the false killer whale , the pygmy killer whale and the short-finned pilot whale . They are susceptible to parasites , and are known to exhibit both external ones like barnacles and remoras , and internal ones, like nematodes , trematodes , cestodes and acanthocephalans . Due to
8944-468: The safe release of dolphins. The eastern tropical Pacific and Southeast Asian populations of the spinner dolphin are listed on Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals ( CMS ), since they have an unfavourable conservation status or would benefit significantly from international co-operation organized by tailored agreements. In addition, the spinner dolphin
9048-425: The same diet as dolphins and are therefore not competitors for food supplies. The Cornwall Wildlife Trust records about one such death a year. Possible explanations include misdirected infanticide, misdirected sexual aggression or play behaviour . Dolphin copulation happens belly to belly; though many species engage in lengthy foreplay , the actual act is usually brief, but may be repeated several times within
9152-586: The second largest brain mass of any animal on earth, next to the sperm whale . The brain to body mass ratio in some is second only to humans. Self-awareness is seen, by some, to be a sign of highly developed, abstract thinking. 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. Research in this field has suggested that cetaceans, among others, possess self-awareness. The most widely used test for self-awareness in animals
9256-485: The shore during foraging trips, and the individuals that occupy the same bay may change daily. Some individual dolphins do not always go to a bay to rest; however, in Hawaii, dolphins do seem to return to the same site each trip. Spinner dolphins live in an open and loose social organization. The spinner dolphins of Hawaii live in family groups, but also have associations with others beyond their groups. Mothers and calves form strong social bonds. Spinner dolphins seem to have
9360-538: The shrinking and eventual disappearance of the hind limbs which took place with the first odontocetes and mysticetes 34 million years ago. The modern dolphin skeleton has two small, rod-shaped pelvic bones thought to be vestigial hind limbs. In October 2006, an unusual bottlenose dolphin was captured in Japan; it had small fins on each side of its genital slit, which scientists believe to be an unusually pronounced development of these vestigial hind limbs. Today,
9464-413: The similar Clymene dolphin , which is often called the short-snouted spinner dolphin. The species was described by John Gray in 1828. The four named subspecies are: The species, though, displays greater variety than these subspecies might indicate. A hybrid form characterized by its white belly inhabits the eastern Pacific. Other less distinct groupings inhabit other oceans. The species name comes from
9568-515: The spinner dolphin foraging and feeding at night, in certain regions, such as Hawaii and northern Brazil, dolphins spend the daytime resting in shallow bays near deep water. Spinner dolphins rest as a single unit, moving back and forth slowly in a tight formation but just out of contact with one another. These resting behaviors are observed for about four to five hours daily. During rest periods, spinner dolphins rely on vision rather than echolocation. At dusk, they travel offshore to feed. They travel along
9672-399: The stock and a minimum population estimation. These stock assessments are created through research conducted by programs at NOAA research science centers which are located in Hawaii, Massachusetts, Alaska, Florida, Washington, and California. Research contributions are also made by researchers not affiliated with the previously mentioned programs as well. The Marine Mammal Commission (MMC)
9776-430: The stunned fish. Corralling 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. Some species also whack fish with their flukes, stunning them and sometimes knocking them out of the water. Reports of cooperative human-dolphin fishing date back to
9880-410: The subcutaneous blubber or fat depends on the dolphin's health, development, location, reproductive state, and how well it feeds. This fat is thickest on the dolphin's back and belly. Most of the dolphin's body fat is accumulated in a thick layer of blubber. Blubber differs from fat in that, in addition to fat cells, it contains a fibrous network of connective tissue. The blubber functions to streamline
9984-634: The swimmers or charging the sharks to make them go away. Dolphins communicate using a variety of clicks, whistle-like sounds and other vocalizations. Dolphins also use nonverbal communication by means of touch and posturing . Dolphins also display culture, something long believed to be unique to humans (and possibly other primate species). In May 2005, a discovery in Australia found Indo-Pacific bottlenose dolphins ( Tursiops aduncus ) teaching their young to use tools. They cover their snouts with sponges to protect them while foraging. This knowledge
10088-712: The take and exploitation of any marine mammal without appropriate authorization, which may only be given by the Service. Permits may be issued for scientific research, public display, and the importation/exportation of marine mammal parts and products upon determination by the Service that the issuance is consistent with the MMPA's regulations. The two types of permits issued by the National Marine Fisheries Service 's Office of Protected Resources are incidental and directed. Incidental permits, which allow for some unintentional taking of small numbers of marine mammal, are granted to U.S. citizens who engage in
10192-428: The temperature drops, the blubber constricts the blood vessels to reduce blood flow in the dolphin. This allows the dolphin to spend less energy heating its own body, ultimately keeping the animal warmer without burning energy as quick. In order to release heat, the heat must pass the blubber layer. There are thermal windows that lack blubber, are not fully insulated and are somewhat thin and highly vascularized, including
10296-403: The two species of hippo. Dolphins have torpedo-shaped bodies with generally non-flexible necks, limbs modified into flippers, a tail fin, and bulbous heads. Dolphin skulls have small eye orbits, long snouts, and eyes placed on the sides of its head; they lack external ear flaps. Dolphins range in size from the 1.7 m (5 ft 7 in) long and 50 kg (110 lb) Maui's dolphin to
10400-490: The water front first and twists its body as it rises into the air. When it reaches its maximum height, the dolphin descends back into the water, landing on its side. A dolphin can make two to seven spins in one leap; the swimming and rotational speed of the dolphin as it spins underwater affects the number of spins it can do while airborne. These spins may serve several functions. Some of these functions are believed by experts to be acoustic signaling or communication. Another reason
10504-435: The water, which allows them to travel faster. Their skeletal anatomy allows them to be fast swimmers. All species have a dorsal fin to prevent themselves from involuntarily spinning in the water. Some dolphins are adapted for diving to great depths. In addition to their streamlined bodies, some can selectively slow their heart rate to conserve oxygen. Some can also re-route blood from tissue tolerant of water pressure to
10608-524: The world or have been reported in the wild, such as a bottlenose- Atlantic spotted hybrid. The best known hybrid is the wholphin , a false killer whale-bottlenose dolphin hybrid. The wolphin is a fertile hybrid. Two wolphins currently live at the Sea Life Park in Hawaii; the first was born in 1985 from a male false killer whale and a female bottlenose. Wolphins have also been observed in the wild. Dolphins are descendants of land-dwelling mammals of
10712-484: Was created in 1972 through the MMPA to serve as an organization that provides oversight over conservation policies, regulations and programs being carried out to ensure they are carried out effectively by the federal agencies responsible for them. Their responsibilities also include ensuring the United States adhere to international agreements that relate to marine mammal conservation “including, but not limited to,
10816-718: Was divided between the Secretary of the Interior through the U.S. Fish and Wildlife Service (Service), and the Secretary of Commerce , which is delegated to the National Oceanic and Atmospheric Administration (NOAA). Subsequently, a third federal agency, the Marine Mammal Commission (MMC), was established to review existing policies and make recommendations to the Service and the NOAA better implement
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