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115-540: Beluga whales are frequently seen in the bay. Mamga Bay is a small bay located on the northwestern side of Tugur Bay . It lies in the northwestern Sea of Okhotsk . The bay is open to the south and a small river, the Mamga, flows into it from the west. New London and Hawaiian whaling schooners wintered in Mamga Bay from 1856 to 1862. They called it Caroline Harbor , after the schooner Caroline (106 tons), which

230-589: A marine mammal buried beneath the fields of rural Vermont. The remains were found to be preserved in the sediments of the Champlain Sea , an extension of the Atlantic Ocean within the continent resulting from the rise in sea level at the end of the ice ages some 12,000 years ago. Today, the Charlotte whale is the official Vermont State Fossil (making Vermont the only state whose official fossil

345-399: A bat species that feeds on moths , uses a particularly low frequency of 12.7 kHz that cannot be heard by moths. Echolocation calls can be composed of two different types of frequency structure: frequency modulated (FM) sweeps, and constant frequency (CF) tones. A particular call can consist of one, the other, or both structures. An FM sweep is a broadband signal – that is, it contains

460-440: A bat's perception. First, it establishes how quickly the bat's auditory scene information is updated. For example, bats increase the repetition rate of their calls (that is, decrease the pulse interval) as they home in on a target. This allows the bat to get new information regarding the target's location at a faster rate when it needs it most. Secondly, the pulse interval determines the maximum range that bats can detect objects. This

575-417: A beluga to "talk" by using these sounds to identify three different objects, offering hope that humans may one day be able to communicate effectively with sea mammals. A similar observation has been made by Canadian researchers, where a beluga which died in 2007 "talked" when he was still a subadult. Another example is NOC , a beluga whale that could mimic the rhythm and tone of human language. Beluga whales in

690-431: A beluga's life expectancy was rarely more than 30 years. The method used to calculate the age of a beluga is based on counting the layers of dentine and dental cement in a specimen's teeth, which were originally thought to be deposited once or twice a year. The layers can be readily identified as one layer consists of opaque dense material and the other is transparent and less dense. It is therefore possible to estimate

805-421: A calf or if they are pregnant. After giving birth, dominant females will return the calf back to their mother. Additionally, male calves will temporarily leave their mothers to interact with an adult male who can serve as a role model for the calf, before they return to their mothers. Male calves are also frequently seen interacting with each other. Belugas are slower swimmers than the other toothed whales, such as

920-401: A calf. Experts consider this interaction with the objects to be a substitute behavior . In captivity, mothering behavior among belugas depends on the individual. Some mothers are extremely attentive while other mothers are so blasé, that they have actually lost their calves. In aquaria, there have been cases where dominant females have stolen calves from mothers, particularly if they have lost

1035-480: A common source of food for echolocating bats and some insects (moths in particular) can hear the calls of predatory bats. However the evolution of hearing organs in moths predates the origins of bats, so while many moths do listen for approaching bat echolocation their ears did not originally evolve in response to selective pressures from bats. These moth adaptations provide selective pressure for bats to improve their insect-hunting systems and this cycle culminates in

1150-533: A constant frequency for up to 100 milliseconds. An FM component is excellent for hunting prey while flying in close, cluttered environments. Two aspects of the FM signal account for this fact: the precise target localization conferred by the broadband signal, and the short duration of the call. The first of these is essential because in a cluttered environment, the bats must be able to resolve their prey from large amounts of background noise. The 3D localization abilities of

1265-623: A discontinuous circumpolar distribution in Arctic and sub-Arctic waters. During the summer, they can mainly be found in deep waters ranging from 76°N to 80°N , particularly along the coasts of Alaska , northern Canada, western Greenland and northern Russia. The southernmost extent of their range includes isolated populations in the St. Lawrence River in the Atlantic, and the Amur River delta,

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1380-436: A dive, these animals will reduce their heart rate from 100 beats a minute to between 12 and 20. Blood flow is diverted away from certain tissues and organs and towards the brain , heart and lungs , which require a constant oxygen supply. The amount of oxygen dissolved in the blood is 5.5%, which is greater than that found in land-based mammals and is similar to that of Weddell seals (a diving marine mammal). One study found

1495-407: A downward sweep through a range of frequencies. A CF tone is a narrowband signal: the sound stays constant at one frequency throughout its duration. Echolocation calls in bats have been measured at intensities anywhere between 60 and 140 decibels . Certain bat species can modify their call intensity mid-call, lowering the intensity as they approach objects that reflect sound strongly. This prevents

1610-541: A female beluga had 16.5 L of oxygen dissolved in her blood. Lastly, the beluga's muscles contain high levels of the protein myoglobin , which stores oxygen in muscle. Myoglobin concentrations in belugas are several times greater than for terrestrial mammals, which help prevent oxygen deficiency during dives. Beluga whales often accompany bowhead whales , for curiosity and to secure polynya feasibility to breathe as bowheads are capable of breaking through ice from underwater by headbutting. Belugas play an important role in

1725-400: A few centimetres behind their eyes; each hole communicates with an external auditory conduit and an eardrum . It is not known if these organs are functional or simply vestigial . Belugas are able to see within and outside of water, but their vision is relatively poor when compared to dolphins. Their eyes are especially adapted to seeing under water, although when they come into contact with

1840-426: A few days be hundreds of miles away from that pod. Beluga whale pods can be grouped into three categories, nurseries (which consist of mother and calves), bachelors (which consist of all males) and mixed groups. Mixed groups contain animals of both sexes. Many hundreds and even thousands of individuals can be present when the pods join in river estuaries during the summer. This can represent a significant proportion of

1955-410: A few hours after birth; thereafter, they feed at intervals around an hour. Studies of captive females have indicated their milk composition varies between individuals and with the stage of lactation; it has an average content of 28% fat, 11% protein, 60.3% water, and less than 1% residual solids. The milk contains about 92 cal per ounce . The calves remain dependent on their mothers for nursing for

2070-401: A flying target from a stationary one. The horseshoe bats hunt in this way. Additionally, because the signal energy of a CF call is concentrated into a narrow frequency band, the operational range of the call is much greater than that of an FM signal. This relies on the fact that echoes returning within the narrow frequency band can be summed over the entire length of the call, which maintains

2185-450: A large frontal prominence. Another distinctive characteristic it possesses is the melon is malleable; its shape is changed during the emission of sounds. The beluga is able to change the shape of its head by blowing air around its sinuses to focus the emitted sounds. This organ contains fatty acids , mainly isovaleric acid (60.1%) and long-chain branched acids (16.9%), a very different composition from its body fat, and which could play

2300-490: A maximum frequency of 100 to 120 kHz when transferred to Kaneohe Bay in Hawaii . The difference in frequencies is thought to be a response to the difference in environmental noise in the two areas. In special circumstances, beluga whale sounds have been reported to resemble human speech. These animals communicate using sounds of high frequency; their calls can sound like bird songs, so belugas were nicknamed "canaries of

2415-403: A mechanism for regulating body temperature , as the arteries feeding the fin's muscles are surrounded by veins that dilate or contract to gain or lose heat. The tailfin is flat with two oar-like lobes, it does not have any bones, and is made up of hard, dense, fibrous connective tissue. The tailfin has a distinctive curvature along the lower edge. The longitudinal muscles of the back provide

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2530-514: A millisecond, as the fast downward sweep of the call does not remain at any one frequency for long. The structure of a CF signal is adaptive in that it allows the CF-bat to detect both the velocity of a target, and the fluttering of a target's wings as Doppler shifted frequencies. A Doppler shift is an alteration in sound wave frequency, and is produced in two relevant situations: when the bat and its target are moving relative to each other, and when

2645-538: A period up to 475 days (15.8 months). During the mating season, the testes of belugas double in weight. Testosterone levels increase, but seems to be independent of copulation. Copulation typically takes place between 3 and 4 AM. Calves are born over a protracted period that varies by location. In the Canadian Arctic, calves are born between March and September, while in Hudson Bay , the peak calving period

2760-442: A pulse interval of 5 ms (typical of a bat in the final moments of a capture attempt), the bat can only detect objects up to 85 cm away. Therefore, the bat constantly has to make a choice between getting new information updated quickly and detecting objects far away. The major advantage conferred by an FM signal is extremely precise range discrimination, or localization , of the target. J. A. Simmons demonstrated this effect with

2875-466: A role in its echolocation system. Unlike many dolphins and whales, the seven vertebrae in the neck are not fused together, allowing the animal to turn its head laterally without needing to rotate its body. This gives the head a lateral manoeuvrability that allows an improved field of view and movement and helps in catching prey and evading predators in deep water. The rostrum has about eight to ten small, blunt and slightly curved teeth on each side of

2990-411: A series of experiments that showed how bats using FM signals could distinguish between two separate targets even when the targets were less than half a millimeter apart. This ability is due to the broadband sweep of the signal, which allows for better resolution of the time delay between the call and the returning echo, thereby improving the cross correlation of the two. If harmonic frequencies are added to

3105-654: A single continuous trace on a sound spectrogram , and a series of calls comprising a sequence or pass) can last anywhere from less than 3 to over 50 milliseconds in duration. Pulse duration is around 3 milliseconds in FM bats such as Phyllostomidae and some Vespertilionidae; between 7 and 16 milliseconds in Quasi-constant-frequency (QCF) bats such as other Vespertilionidae, Emballonuridae, and Molossidae; and between 11 milliseconds (Hipposideridae) and 52 milliseconds (Rhinolophidae) in CF bats. Duration depends also on

3220-770: A single origin in Chiroptera, i.e. that it was basal to the group, and was subsequently lost in the family Pteropodidae . Later, the genus Rousettus in the Pteropodidae family evolved a different mechanism of echolocation using a system of tongue-clicking: Yangochiroptera fruit bats Rousettus Megadermatidae horseshoe bats Echolocating bats occupy a diverse set of ecological conditions; they can be found living in environments as different as Europe and Madagascar , and hunting for food sources as different as insects, frogs, nectar, fruit, and blood. The characteristics of an echolocation call are adapted to

3335-447: A target ( multibeam sonar ), animal echolocation has only one transmitter and two receivers (the ears) positioned slightly apart. The echoes returning to the ears arrive at different times and at different intensities, depending on the position of the object generating the echoes. The time and loudness differences are used by the animals to perceive distance and direction. With echolocation, the bat or other animal can tell, not only where it

3450-506: A variety of fish species including saffron cod, rainbow smelt , walleye pollock, Pacific salmon , Pacific herring and several species of flounder and sculpin. The primary invertebrate consumed is shrimp. The primary prey item in regard to fish species for belugas in Bristol Bay appears to be the five species of salmon, with sockeye being the most prevalent. Smelt is also another common fish family eaten by belugas in this region. Shrimp

3565-405: A way of preserving heat. The crest is hard and, along with the head, can be used to open holes in ice up to 8 cm (3.1 in) thick. The beluga has a very specialised sense of hearing and its auditory cortex is highly developed. It can hear sounds within the range of 1.2 to 120  kHz , with the greatest sensitivity between 10 and 75 kHz, where the average hearing range for humans

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3680-580: A whaling station on the tip of the peninsula that forms the eastern side of the bay. Under the command of a Captain Elfsberg of the Imperial Navy , the two schooners Ayan and Caroline obtained 2,700 bbls of whale oil and 31,000 lbs of whalebone between 1863 and 1865. In 1865 the station and one of the schooners, the Caroline , were sold to Otto Wilhelm Lindholm, who operated another station at

3795-420: A wide range of movement while they are searching for food on the ocean floor. Some animals have been observed to suck up water and then forcefully expel it to uncover their prey hidden in the silt on the seabed. As their teeth are neither large nor sharp, belugas must use suction to bring their prey into their mouths; it also means their prey has to be consumed whole, which in turn means it cannot be too large or

3910-508: Is Coho salmon ( Oncorhynchus kisutch ). In general, the diets of these cetaceans consist mainly of fish; apart from those previously mentioned, other fish they feed on include capelin ( Mallotus villosus ), smelt , sole , flounder , herring , sculpin and other types of salmon . They also consume a great quantity of invertebrates, such as shrimp , squid , crabs , clams , octopus , sea snails , bristle worms and other deep-sea species. Belugas feed mainly in winter as their blubber

4025-429: Is debate as to whether cetacean vocalizations can constitute a language. A study conducted in 2015 determined that European beluga signals share physical features comparable to vowels. These sounds were found to be stable throughout time, but varied among different geographical locations. The further away the populations were from each other, the more varied the sounds were in relation to one another. The beluga inhabits

4140-404: Is 0.02 to 20 kHz. The majority of sounds are most probably received by the lower jaw and transmitted towards the middle ear . In the toothed whales, the lower jawbone is broad with a cavity at its base, which projects towards the place where it joins the cranium . A fatty deposit inside this small cavity connects to the middle ear. Toothed whales also possess a small external auditory hole

4255-469: Is a member of the family Monodontidae , which is in turn part of the parvorder Odontoceti (toothed whales). The Irrawaddy dolphin was once placed in the same family, though recent genetic evidence suggests these dolphins belong to the family Delphinidae . The narwhal is the only other species within the Monodontidae. A skull has been discovered with intermediate characteristics supporting

4370-511: Is a slight difference on the sexual maturation period between males and females. The male beluga whales take seven to nine years to become sexually mature, while the females take four to seven years. Female belugas typically give birth to one calf every three years. Most mating occurs from February to May, but some occurs at other times of year. The beluga may have delayed implantation . Gestation has been estimated to last 12.0 to 14.5 months, but information derived from captive females suggests

4485-515: Is active sonar , using sounds made by the animal itself. Ranging is achieved by measuring the time delay between the animal's own sound emission and any echoes that return from the environment. The relative intensity of sound received at each ear, as well as the time delay between arrival at the two ears, provide information about the horizontal angle (azimuth) from which the reflected sound waves arrive. Unlike some human-made sonars that rely on many extremely narrow beams and many receivers to localize

4600-421: Is again coupled to the wingbeat. This coupling appears to dramatically conserve energy as there is little to no additional energetic cost of echolocation to flying bats. After detecting a potential prey item, echolocating bats increase the rate of pulses, ending with the terminal buzz , at rates as high as 200 clicks/second. During approach to a detected target, the duration of the sounds is gradually decreased, as

4715-404: Is also seen in other mammals, may be present in belugas in the wild. Hybrids have been documented between the beluga and the narwhal (specifically offspring conceived by a beluga father and a narwhal mother), as one, perhaps even as many as three, such hybrids were killed and harvested during a sustenance hunt. Whether or not these hybrids could breed remains unknown. The unusual dentition seen in

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4830-418: Is an Arctic and sub-Arctic cetacean . It is one of two members of the family Monodontidae , along with the narwhal , and the only member of the genus Delphinapterus . It is also known as the white whale , as it is the only cetacean to regularly occur with this colour; the sea canary , due to its high-pitched calls; and the melonhead , though that more commonly refers to the melon-headed whale , which

4945-429: Is an oceanic dolphin . The beluga is adapted to life in the Arctic, with anatomical and physiological characteristics that differentiate it from other cetaceans. Amongst these are its all-white colour and the absence of a dorsal fin , which allows it to swim under ice with ease. It possesses a distinctive protuberance at the front of its head which houses an echolocation organ called the melon , which in this species

5060-402: Is because bats can only keep track of the echoes from one call at a time; as soon as they make another call they stop listening for echoes from the previously made call. For example, a pulse interval of 100 ms (typical of a bat searching for insects) allows sound to travel in air roughly 34 meters so a bat can only detect objects as far away as 17 meters (the sound has to travel out and back). With

5175-414: Is going, but also how big another animal is, what kind of animal it is, and other features. Describing the diversity of echolocation calls requires examination of the frequency and temporal features of the calls. It is the variations in these aspects that produce echolocation calls suited for different acoustic environments and hunting behaviors. The calls of bats have been most intensively researched, but

5290-512: Is in late June, and in Cumberland Sound , most calves are born from late July to early August. Births usually take place in bays or estuaries where the water is between 10 and 15 °C. Newborns are about 1.5 m (4 ft 11 in) long, weigh about 80 kg (180 lb), and are grey in colour. They are able to swim alongside their mothers immediately after birth. The newborn calves nurse under water and initiate lactation

5405-530: Is large and deformable. The beluga's body size is between that of a dolphin and a true whale, with males growing up to 5.5 m (18 ft) long and weighing up to 1,600 kg (3,530 lb). This whale has a stocky body. Like many cetaceans, a large percentage of its weight is blubber (subcutaneous fat). Its sense of hearing is highly developed and its echolocation allows it to move about and find breathing holes under sheet ice. Belugas are gregarious and form groups of 10 animals on average, although during

5520-646: Is made possible by the fact that the long, narrowband call allows the bat to detect Doppler shifts, which would be produced by an insect moving either towards or away from a perched bat. Echolocation occurs in a variety of mammals and birds as described below. It evolved repeatedly, an example of convergent evolution . Chinese pygmy dormice Bats Whales Shrews Solenodons Tenrecs Oilbirds Swiftlets Echolocating bats use echolocation to navigate and forage, often in total darkness. They generally emerge from their roosts in caves, attics, or trees at dusk and hunt for insects into

5635-399: Is rarely mistaken for any other species, because it is completely white or whitish-grey in colour. Calves are usually born grey, and by the time they are a month old, have turned dark grey or blue grey. They then start to progressively lose their pigmentation until they attain their distinctive white colouration, at the age of seven years in females and nine in males. The white colouration of

5750-608: Is stocky and fusiform (cone-shaped with the point facing backwards), and they frequently have folds of fat, particularly along the ventral surface. Between 40% and 50% of their body weight is fat, which is a higher proportion than for cetaceans that do not inhabit the Arctic, where fat only represents 30% of body weight. The fat forms a layer that covers all of the body except the head, and it can be up to 15 cm (5.9 in) thick. It acts as insulation in waters with temperatures between 0 and 18 °C, as well as being an important reserve during periods without food. The adult beluga

5865-432: Is that of a still extant animal). Its body is round, particularly when well fed, and tapers less smoothly to the head than the tail. The sudden tapering to the base of its neck gives it the appearance of shoulders, unique among cetaceans. The tail-fin grows and becomes increasingly and ornately curved as the animal ages. The flippers are broad and short—making them almost square-shaped. Preliminary investigations suggested

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5980-754: Is the energy of the sound. Bats evolved at the start of the Eocene epoch, around 64 mya . The Yangochiroptera appeared some 55 mya, and the Rhinolophoidea some 52 mya. There are two hypotheses about the evolution of echolocation in bats. The first suggests that laryngeal echolocation evolved twice, or more, in Chiroptera, at least once in the Yangochiroptera and at least once in the horseshoe bats (Rhinolophidae): Yangochiroptera fruit bats Rousettus Megadermatidae horseshoe bats The second proposes that laryngeal echolocation had

6095-623: Is the most prevalent invertebrate prey item. The most common prey items for belugas in Cook Inlet appear to be salmon, cod and smelt. Animals in captivity eat 2.5% to 3.0% of their body weight per day, which equates to 18.2 to 27.2 kg (40 to 60 lb). Like their wild counterparts, captive belugas were found to eat less in the fall. Foraging on the seabed typically takes place at depths between 20 and 40 m (66 and 131 ft), although they can dive to depths of 700 m (2,300 ft) in search of food. Their flexible necks provide

6210-568: Is thickest in later winter and early spring, and thinnest in the fall. Inuit observation has led scientists to believe that belugas do not hunt during migration, at least in Hudson Bay. The diet of Alaskan belugas is quite diverse and varies depending on season and migratory behavior. Belugas in the Beaufort Sea mainly feed on staghorn and shorthorn sculpin, walleye pollock , Arctic cod , saffron cod and Pacific sand lance . Shrimp are

6325-496: Is thought to number around 200,000. They are migratory and the majority of groups spend the winter around the Arctic ice cap ; when the sea ice melts in summer, they move to warmer river estuaries and coastal areas. Some populations are sedentary and do not migrate over great distances during the year. The native peoples of North America and Russia have hunted belugas for many centuries. They were also hunted by non-natives during

6440-456: Is unclear as to whether belugas receive a different number of layers per year depending on the age of the animal (for example young belugas may only receive an additional one layer per year), or simply just one layer per year or every other year. The species presents a moderate degree of sexual dimorphism , as the males are 25% longer than the females and are sturdier. Adult male belugas can range from 3.5 to 5.5 m (11 to 18 ft), while

6555-591: The Shantar Islands and the waters surrounding Sakhalin Island in the Sea of Okhotsk . Animal echolocation Echolocation , also called bio sonar , is a biological active sonar used by several animal groups, both in the air and underwater. Echolocating animals emit calls and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify

6670-533: The oilbird . Some prey animals that are hunted by echolocating bats take active countermeasures to avoid capture. These include predator avoidance, attack deflection, and the use of ultrasonic clicks, which have evolved multiple functions including aposematism , mimicry of chemically defended species , and echolocation jamming. The term echolocation was coined by 1944 by the American zoologist Donald Griffin , who, with Robert Galambos , first demonstrated

6785-964: The 19th century and part of the 20th century. Hunting of belugas is not controlled by the International Whaling Commission , and each country has developed its own regulations in different years. Currently, some Inuit in Canada and Greenland, Alaska Native groups and Russians are allowed to hunt belugas for consumption as well as for sale, as aboriginal whaling is excluded from the International Whaling Commission 1986 moratorium on hunting. The numbers have dropped substantially in Russia and Greenland, but not in Alaska and Canada. Other threats include natural predators ( polar bears and killer whales ), contamination of rivers (as with polychlorinated biphenyl (PCBs) which bioaccumulate up

6900-411: The CF call, both of which confer excellent prey-detection abilities. First, the greater working range of the call allows bats to detect targets present at great distances – a common situation in open environments. Second, the length of the call is also suited for targets at great distances: in this case, there is a decreased chance that the long call will overlap with the returning echo. The latter strategy

7015-460: The FM signal, then this localization becomes even more precise. One possible disadvantage of the FM signal is a decreased operational range of the call. Because the energy of the call is spread out among many frequencies, the distance at which the FM-bat can detect targets is limited. This is in part because any echo returning at a particular frequency can only be evaluated for a brief fraction of

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7130-544: The St. Lawrence River are listed as endangered. Belugas are one of the most commonly kept cetaceans in captivity and are housed in aquariums, dolphinariums and wildlife parks in North America, Europe and Asia. They are considered charismatic because of their docile demeanour and characteristic smile, communicative nature, and supple, graceful movement. The beluga was first described in 1776 by Peter Simon Pallas . It

7245-423: The age of the individual by extrapolating the number of layers identified and the estimated frequency with which the deposits are laid down. A 2006 study using radiocarbon dating of the dentin layers showed the deposit of this material occurs with a lesser frequency (once per year) than was previously thought. The study therefore estimated belugas can live for 70 or 80 years. However, recent studies suggest that it

7360-440: The air, the crystalline lens and the cornea adjust to overcome the associated myopia (the range of vision under water is short). A beluga's retina has cones and rods , which also suggests they can see in low light. The presence of cone cells indicates they can see colours, although this suggestion has not been confirmed. Glands located in the medial corner of their eyes secrete an oily, gelatinous substance that lubricates

7475-490: The ascending and descending movement of the tailfin, which has a similar thermoregulation mechanism to the pectoral fins. Belugas have a dorsal ridge, rather than a dorsal fin . The absence of the dorsal fin is reflected in the genus name of the species— apterus the Greek word for "wingless". The evolutionary preference for a dorsal ridge rather than a fin is believed to be an adaptation to under-ice conditions, or possibly as

7590-411: The bat can get an almost continuous stream of information – essential when objects are close, because they will pass by quickly – without confusing which echo corresponds to which call. A CF component is often used by bats hunting for prey while flying in open, clutter-free environments, or by bats that wait on perches for their prey to appear. The success of the former strategy is due to two aspects of

7705-459: The bats themselves. Echolocating bats generate ultrasound via the larynx and emit the sound through the open mouth or, much more rarely, the nose. The latter is most pronounced in the horseshoe bats ( Rhinolophus spp. ). Bat echolocation calls range in frequency from 14,000 to well over 100,000 Hz, mostly beyond the range of the human ear (typical human hearing range is considered to be from 20 Hz to 20,000 Hz). Bats may estimate

7820-501: The beam of sound. They use this ability when moving around thick Arctic ice sheets, to find areas of unfrozen water for breathing, or air pockets trapped under the ice. Some evidence indicates that belugas are highly sensitive to noise produced by humans. In one study, the maximum frequencies produced by an individual located in San Diego Bay , California , were between 40 and 60 kHz. The same individual produced sounds with

7935-416: The beluga's mammalian ancestors, and are firmly bound together by connective tissue . The fins are small in relation to the size of the body, rounded and oar-shaped and slightly curled at the tips. These versatile extremities are mainly used as a rudder to control direction, to work in synchrony with the tailfin and for agile movement in shallow waters up to 3 m (9.8 ft) deep. The fins also contain

8050-613: The beluga's range varied with that of the polar ice packs expanding during ice ages and contracting when the ice retreated. Counter-evidence to this theory comes from the finding in 1849 of fossilised beluga bones in Vermont in the United States, 240 km (150 mi) from the Atlantic Ocean. The bones were discovered during construction of the first railroad between Rutland and Burlington in Vermont, when workers unearthed

8165-440: The belugas run the risk of it getting stuck in their throats. They also join into coordinated groups of five or more to feed on shoals of fish by steering the fish into shallow water, where the belugas then attack them. For example, in the estuary of the Amur River , where they mainly feed on salmon, groups of six or eight individuals join to surround a shoal of fish and prevent their escape. Individuals then take turns feeding on

8280-406: The bones of a mysterious animal in Charlotte . Buried nearly 10 ft (3.0 m) below the surface in a thick blue clay , these bones were unlike those of any animal previously discovered in Vermont. Experts identified the bones as those of a beluga. Because Charlotte is over 150 mi (240 km) from the nearest ocean, early naturalists were at a loss to explain the presence of the bones of

8395-455: The broadband signal enable the bat to do exactly that, providing it with what Simmons and Stein (1980) call a "clutter rejection strategy". This strategy is further improved by the use of harmonics, which, as previously stated, enhance the localization properties of the call. The short duration of the FM call is also best in close, cluttered environments because it enables the bat to emit many calls extremely rapidly without overlap. This means that

8510-477: The early Pliocene (3–5 million years ago). Fossil evidence from Baja California and Virginia indicate the family once inhabited warmer waters. A fossil of the monodontid Casatia thermophila , from five million years ago, provides the strongest evidence that monodontids once inhabited warmer waters, as the fossil was found alongside fossils of tropical species such as bull and tiger sharks. The fossil record also indicates that, in comparatively recent times,

8625-517: The elevation of targets by interpreting the interference patterns caused by the echoes reflecting from the tragus , a flap of skin in the external ear. Individual bat species echolocate within specific frequency ranges that suit their environment and prey types. This has sometimes been used by researchers to identify bats flying in an area simply by recording their calls with ultrasonic recorders known as "bat detectors". However, echolocation calls are not always species specific and some bats overlap in

8740-549: The end of the season to either Honolulu or San Francisco . Lindholm and his men wintered in the houses abandoned by the RAC, while the schooners were hauled up onto the riverbank at the mouth of the Mamga River to protect them from being damaged by the ice. In 1870 and 1871 he took down two of the houses on the point and loaded them onto one of his schooners and sailed to Nakhodka for the winter, leaving subordinates in command of

8855-465: The eye and helps flush out foreign bodies. This substance forms a film that protects the cornea and the conjunctiva from pathogenic organisms. Studies on captive animals show they seek frequent physical contact with other belugas. Areas in the mouth have been found that could act as chemoreceptors for different tastes, and they can detect the presence of blood in water, which causes them to react immediately by displaying typical alarm behaviour. Like

8970-429: The females measure 3 to 4.1 m (9.8 to 13.5 ft). Males weigh between 1,100 and 1,600 kg (2,430 and 3,530 lb), and occasionally up to 1,900 kg (4,190 lb) while females weigh between 700 and 1,200 kg (1,540 and 2,650 lb). They rank as mid-sized species among toothed whales. Individuals of both sexes reach their maximum size by the time they are 10 years old. The beluga's body shape

9085-494: The first year, when their teeth appear. After this, they start to supplement their diets with shrimp and small fish. The majority of the calves continue nursing until they are 20 months old, although occasionally lactation can continue for more than two years, and lactational anoestrus may not occur. Alloparenting (care by females different from the mother) has been observed in captive belugas, including spontaneous and long-term milk production. This suggests this behaviour, which

9200-510: The fish. Estimations of the age of sexual maturity for beluga whales vary considerably; the majority of authors estimate males reach sexual maturity when they are between nine and fifteen years old, and females reach maturity between eight and fourteen years old. The average age at which females first give birth is 8.5 years and fertility begins to decrease when they are 25, eventually undergoing menopause, and ceasing reproductive potential with no births recorded for females older than 41. There

9315-585: The food chain), climate change and infectious diseases . The beluga was placed on the International Union for Conservation of Nature 's Red List in 2008 as being "near threatened"; the subpopulation from the Cook Inlet in Alaska is considered critically endangered and is under the protection of the United States' Endangered Species Act . Of all seven extant Canadian beluga populations, those inhabiting eastern Hudson Bay , Ungava Bay , and

9430-565: The former is now more popular. The English name comes from the Russian белу́га, which derives from the word белый ( bélyj ), meaning "white". Nowadays the word белу́га in Russian refers to the beluga sturgeon , while the whale is called almost similarly - белу́ха ("belúha"). The whale is also colloquially known as the "sea canary" on account of its high-pitched squeaks, squeals, clucks, and whistles. A Japanese researcher claimed that he taught

9545-451: The genome of a beluga whale was sequenced, comprising 2.327 Gbp of assembled genomic sequence that encoded 29,581 predicted genes. The authors estimated that the genome-wide sequence similarity between beluga whales and killer whales is 97.87%. The beluga's earliest known distinctive ancestors include the prehistoric Denebola brachycephala from the late Miocene epoch (9–10 million years ago), and Bohaskaia monodontoides , from

9660-528: The head of Tugur Bay. With the Caroline and another schooner, the Hannah Rice (160 tons), purchased the following year, Lindholm cruised for bowhead whales in Tugur Bay and in adjacent bays and gulfs. Whales were towed to the station, where they were flensed on the beach and their blubber rendered into oil at a tryworks on the point. A chartered vessel from Nikolayevsk took aboard the oil and bone at

9775-467: The hypothesis that hybridisation is possible between these two species. The name of the genus , Delphinapterus , means "dolphin without fin" (from the Greek δελφίν ( delphin ), dolphin and απτερος ( apteros ), without fin) and the species name leucas means "white" (from the Greek λευκας ( leukas ), white). The Red List of Threatened Species gives both beluga and white whale as common names, though

9890-683: The inventor Hiram Maxim independently proposed that bats used sound below the human auditory range to avoid obstacles. In 1920, the English physiologist Hamilton Hartridge correctly proposed instead that bats used frequencies above the range of human hearing . Echolocation in odontocetes (toothed whales) was not properly described until two decades after Griffin and Galambos' work, by Schevill and McBride in 1956. However, in 1953, Jacques Yves Cousteau suggested in his first book, The Silent World , that porpoises had something like sonar , judging by their navigational abilities. Echolocation

10005-412: The jaw and a total of 36 to 40 teeth. Belugas do not use their teeth to chew, but for catching hold of their prey; they then tear them up and swallow them nearly whole. Belugas only have a single spiracle , which is located on the top of the head behind the melon, and has a muscular covering, allowing it to be completely sealed. Under normal conditions, the spiracle is closed and an animal must contract

10120-410: The killer whale and the common bottlenose dolphin , because they are less hydrodynamic and have limited movement of their tail-fins, which produce the greatest thrust. They frequently swim at speeds between 3 and 9 km/h (1.9 and 5.6 mph), although they are able to maintain a speed of 22 km/h for up to 15 min. Unlike most cetaceans, they are capable of swimming backwards. Belugas swim on

10235-544: The most common invertebrate eaten, with octopus, amphipods and echiurids being other sources of invertebrate prey. The most common prey species for belugas in the Eastern Chukchi Sea appears to be shrimp, echiurid worms, cephalopods and polychaetes . The largest prey item consumed by beluga whales in the Eastern Chukchi Sea seems to be saffron cod. Beluga whales in the Eastern Bering Sea feed on

10350-416: The muscular covering to open the spiracle. A beluga's thyroid gland is larger than that of terrestrial mammals —weighing three times more than that of a horse—which helps it to maintain a greater metabolism during the summer when it lives in river estuaries. It is the marine cetacean that most frequently develops hyperplastic and neoplastic lesions of the thyroid. The fins retain the bony vestiges of

10465-413: The night. Using echolocation, bats can determine how far away an object is, the object's size, shape and density, and the direction (if any) that an object is moving. Their use of echolocation, along with powered flight, allows them to occupy a niche where there are often many insects (that come out at night since there are fewer predators then), less competition for food, and fewer species that may prey on

10580-849: The objects. Echolocation is used for navigation , foraging , and hunting prey . Echolocation calls can be frequency modulated (FM, varying in pitch during the call) or constant frequency (CF). FM offers precise range discrimination to localize the prey, at the cost of reduced operational range. CF allows both the prey's velocity and its movements to be detected by means of the Doppler effect . FM may be best for close, cluttered environments, while CF may be better in open environments or for hunting while perched. Echolocating animals include mammals, especially odontocetes (toothed whales) and some bat species, and, using simpler forms, species in other groups such as shrews . A few bird species in two cave-dwelling bird groups echolocate, namely cave swiftlets and

10695-425: The other one popped them. There have also been reports of beluga whales copying and imitating one another, similar to a game of Simon-says. There have also been reports of them displaying physical affection, via mouth to mouth contact. They also show a great deal of curiosity towards humans and frequently approach the windows in the tanks to observe them. Belugas also show a great degree of curiosity towards humans in

10810-450: The other toothed whales, their brains lack olfactory bulbs and olfactory nerves, which suggests they do not have a sense of smell. These cetaceans are highly sociable and they regularly form small groups, or pods, that may contain between two and 25 individuals, with an average of 10 members. Pods tend to be unstable, meaning individuals tend to move from pod to pod. Radio tracking has even shown belugas can start out in one pod and within

10925-444: The particular environment, hunting behavior, and food source of the particular bat. The adaptation of echolocation calls to ecological factors is constrained by the phylogenetic relationship of the bats, leading to a process known as descent with modification, and resulting in the diversity of the Chiroptera today. Bats can inadvertently jam each other, and in some situations they may stop calling to avoid jamming. Flying insects are

11040-582: The phenomenon in bats. As Griffin described in his book, the 18th century Italian scientist Lazzaro Spallanzani had, by means of a series of elaborate experiments, concluded that when bats fly at night, they rely on some sense besides vision, but he did not discover that the other sense was hearing. The Swiss physician and naturalist Louis Jurine repeated Spallanzani's experiments (using different species of bat), and concluded that when bats hunt at night, they rely on hearing. In 1908, Walter Louis Hahn confirmed Spallanzani's and Jurine's findings. In 1912,

11155-501: The principles apply to all echolocation calls. Bat call frequencies range from as low as 11 kHz to as high as 212 kHz. Insectivorous aerial-hawking bats, those that chase prey in the open air, have a call frequency between 20 kHz and 60 kHz, because it is the frequency that gives the best range and image acuity and makes them less conspicuous to insects. However, low frequencies are adaptive for some species with different prey and environments. Euderma maculatum ,

11270-622: The returning echo from deafening the bat. High-intensity calls such as those from aerial-hawking bats (133 dB) are adaptive to hunting in open skies. Their high intensity calls are necessary to even have moderate detection of surroundings because air has a high absorption of ultrasound and because insects' size only provide a small target for sound reflection. Additionally, the so-called "whispering bats" have adapted low-amplitude echolocation so that their prey, moths, which are able to hear echolocation calls, are less able to detect and avoid an oncoming bat. A single echolocation call (a call being

11385-551: The sea". Like the other toothed whales, belugas do not possess vocal cords and the sounds are probably produced by the movement of air between the nasal sacks, which are located near to the blowhole. Belugas are among the most vocal cetaceans. They use their vocalisations for echolocation, during mating and for communication. They possess a large repertoire, emitting up to 11 different sounds, such as cackles, whistles, trills and squawks. They make sounds by grinding their teeth or splashing, but they rarely use body language. There

11500-418: The single remaining skull indicates the hybrid hunted on the seabed, much as walruses do, indicating feeding habits different from those of either parent species. Belugas use sounds and echolocation for movement, communication, to find breathing holes in the ice, and to hunt in dark or turbid waters. They produce a rapid sequence of clicks that pass through the melon, which acts as an acoustic lens to focus

11615-411: The skin is an adaptation to life in the Arctic that allows belugas to camouflage themselves in the polar ice caps as protection against their main predators, polar bears and killer whales . Unlike other cetaceans, the belugas seasonally shed their skin. During the winter, the epidermis thickens and the skin can become yellowish, mainly on the back and fins. When they migrate to the estuaries during

11730-430: The sounds into a beam that is projected forward through the surrounding water. These sounds spread through the water at a speed of nearly 1.6 km per second, some four times faster than the speed of sound in air. The sound waves reflect from objects and return as echoes that are heard and interpreted by the animal. This enables them to determine the distance, speed, size, shape and the object's internal structure within

11845-437: The stage of prey-catching behavior that the bat is engaged in, usually decreasing when the bat is in the final stages of prey capture – this enables the bat to call more rapidly without overlap of call and echo. Reducing duration comes at the cost of having less total sound available for reflecting off objects and being heard by the bat. The time interval between subsequent echolocation calls (or pulses) determines two aspects of

11960-450: The station. Lindholm last mentioned using the station for whaling in 1876, when he sent his steam-brig Sibir to pick up the catch there, but it was visited by the Sibir again in 1879 and 1883. American whaleships visited Mamga to sell goods and receive repairs from ice damage. Beluga whale The beluga whale ( / b ɪ ˈ l uː ɡ ə / ; Delphinapterus leucas )

12075-685: The structure and function of marine resources in the Arctic Ocean , as they are the most abundant toothed whales in the region. They are opportunistic feeders; their feeding habits depend on their locations and the season. For example, when they are in the Beaufort Sea , they mainly eat Arctic cod ( Boreogadus saida ) and the stomachs of belugas caught near Greenland were found to contain rose fish ( Sebastes marinus ), Greenland halibut ( Reinhardtius hippoglossoides ) and northern shrimp ( Pandalus borealis ), while in Alaska their staple diet

12190-435: The summer, they can gather in the hundreds or even thousands in estuaries and shallow coastal areas. They are slow swimmers, but can dive to 700 m (2,300 ft) below the surface. They are opportunistic feeders and their diets vary according to their locations and the season. The majority of belugas live in the Arctic Ocean and the seas and coasts around North America, Russia, and Greenland; their worldwide population

12305-410: The summer, they rub themselves on the gravel of the riverbeds to remove the cutaneous covering. Like most toothed whales , the beluga has a compartment found at the centre of the forehead that contains an organ used for echolocation called a melon , which contains fatty tissue. The shape of the beluga's head is unlike that of any other cetacean, as the melon is extremely bulbous, lobed and visible as

12420-449: The surface between 5% and 10% of the time, while for the rest of the time they swim at a depth sufficient enough to cover their bodies. They do not jump out of the water like dolphins or killer whales. These animals usually only dive to depths to 20 m (66 ft), although they are capable of diving to greater depths. Individual captive animals have been recorded at depths between 400 and 647 m below sea level, while animals in

12535-414: The target's wings are oscillating back and forth. CF-bats must compensate for Doppler shifts, lowering the frequency of their call in response to echoes of elevated frequency – this ensures that the returning echo remains at the frequency to which the ears of the bat are most finely tuned. The oscillation of a target's wings also produces amplitude shifts, which gives a CF-bat additional help in distinguishing

12650-545: The total population and is when they are most vulnerable to being hunted. They are cooperative animals and frequently hunt in coordinated groups. The animals in a pod are very sociable and often chase each other as if they are playing or fighting, and they often rub against each other. Often individuals will surface and dive together in a synchronized manner, in a behavior known as milling. In captivity, they can be seen to be constantly playing, vocalising and swimming around each other. In one case, one whale blew bubbles, while

12765-423: The type of calls they use so recordings of echolocation calls cannot be used to identify all bats. Researchers in several countries have developed "bat call libraries" that contain "reference call" recordings of local bat species to assist with identification. When searching for prey they produce sounds at a low rate (10–20 clicks/second). During the search phase the sound emission is coupled to respiration, which

12880-600: The wild have been recorded as diving to a depth of more than 700 m, with the greatest recorded depth being over 900 m. A dive normally lasts 3 to 5 minutes, but can last up to over 20 minutes. In the shallower water of the estuaries, a diving session may last around two minutes; the sequence consists of five or six rapid, shallow dives followed by a deeper dive lasting up to one minute. The average number of dives per day varies between 31 and 51. All cetaceans, including belugas, have physiological adaptations designed to conserve oxygen while they are under water. During

12995-492: The wild have been reported to imitate human voices. Mitochondrial DNA studies have shown modern cetaceans last shared a common ancestor between 25 and 34 million years ago The superfamily Delphinoidea (which contains monodontids, dolphins and porpoises) split from other toothed whales, odontoceti, between 11 and 15 million years ago. Monodontids then split from dolphins (Delphinidae) and later from porpoises (Phocoenidae), their closest relatives in evolutionary terms. In 2017

13110-477: The wild, and frequently swim alongside boats. They also play with objects they find in the water; in the wild, they do this with wood, plants, dead fish and bubbles they have created. During the breeding season, adults have been observed carrying objects such as plants, nets, and even the skeleton of a dead reindeer on their heads and backs. Captive females have also been observed displaying this behavior, carrying items such as floats and buoys, after they have lost

13225-480: Was the first to winter there in 1856–1857. The four crew left with her all died of scurvy . These schooners acted as tenders to barques , which sent boat crews ahead in the early summer with provisions to cruise for bowhead whales with the schooners before the ships were able to work their way through the ice to Tugur Bay. In the summer of 1862 the Russian-American Company (RAC) established

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