Whales and Dolphins: Behavior, Biology and Distribution

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Scientists have suggested this indicates a strong desire on behalf of the whales to communicate with humans, as whales have a very different vocal mechanism, so imitating human speech likely takes considerable effort. Whales emit two distinct kinds of acoustic signals, which are called whistles and clicks: [60] Clicks are quick broadband burst pulses, used for sonar , although some lower-frequency broadband vocalizations may serve a non-echolocative purpose such as communication; for example, the pulsed calls of belugas.

Whistles are narrow-band frequency modulated FM signals, used for communicative purposes, such as contact calls. Whales are known to teach, learn, cooperate, scheme, and grieve. Whale spindle neurons are found in areas of the brain that are homologous to where they are found in humans, suggesting that they perform a similar function.

Brain size was previously considered a major indicator of the intelligence of an animal. Since most of the brain is used for maintaining bodily functions, greater ratios of brain to body mass may increase the amount of brain mass available for more complex cognitive tasks. Comparison of a particular animal's brain size with the expected brain size based on such allometric analysis provides an encephalisation quotient that can be used as another indication of animal intelligence. Small whales are known to engage in complex play behaviour, which includes such things as producing stable underwater toroidal air-core vortex rings or " bubble rings ".

There are two main methods of bubble ring production: rapid puffing of a burst of air into the water and allowing it to rise to the surface, forming a ring, or swimming repeatedly in a circle and then stopping to inject air into the helical vortex currents thus formed. They also appear to enjoy biting the vortex-rings, so that they burst into many separate bubbles and then rise quickly to the surface. Larger whales are also thought, to some degree, to engage in play. The southern right whale , for example, elevates their tail fluke above the water, remaining in the same position for a considerable amount of time.

This is known as "sailing". It appears to be a form of play and is most commonly seen off the coast of Argentina and South Africa. Humpback whales , among others, are also known to display this behaviour. Whales are fully aquatic creatures, which means that birth and courtship behaviours are very different from terrestrial and semi-aquatic creatures.

Since they are unable to go onto land to calve, they deliver the baby with the fetus positioned for tail-first delivery. This prevents the baby from drowning either upon or during delivery. To feed the new-born, whales, being aquatic, must squirt the milk into the mouth of the calf. Being mammals, they have mammary glands used for nursing calves; they are weaned off at about 11 months of age. This milk contains high amounts of fat which is meant to hasten the development of blubber; it contains so much fat that it has the consistency of toothpaste. Females, referred to as "cows", carry the responsibility of childcare as males, referred to as "bulls", play no part in raising calves.

Most mysticetes reside at the poles. They will then stay there for a matter of months until the calf has developed enough blubber to survive the bitter temperatures of the poles. Until then, the calves will feed on the mother's fatty milk. Most will travel from the Arctic or Antarctic into the tropics to mate, calve, and raise during the winter and spring; they will migrate back to the poles in the warmer summer months so the calf can continue growing while the mother can continue eating, as they fast in the breeding grounds.

The Cetaceans (Whales and Dolphins) of Angola

One exception to this is the southern right whale , which migrates to Patagonia and western New Zealand to calve; both are well out of the tropic zone. Unlike most animals, whales are conscious breathers. All mammals sleep, but whales cannot afford to become unconscious for long because they may drown.

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While knowledge of sleep in wild cetaceans is limited, toothed cetaceans in captivity have been recorded to sleep with one side of their brain at a time, so that they may swim, breathe consciously, and avoid both predators and social contact during their period of rest. A study found that sperm whales sleep in vertical postures just under the surface in passive shallow 'drift-dives', generally during the day, during which whales do not respond to passing vessels unless they are in contact, leading to the suggestion that whales possibly sleep during such dives.

All whales are carnivorous and predatory. Odontocetes, as a whole, mostly feed on fish and cephalopods , and then followed by crustaceans and bivalves. All species are generalist and opportunistic feeders. Mysticetes, as a whole, mostly feed on krill and plankton , followed by crustaceans and other invertebrates. A few are specialists. Examples include the blue whale , which eats almost exclusively krill, the minke whale , which eats mainly schooling fish, the sperm whale , which specialize on squid , and the grey whale which feed on bottom-dwelling invertebrates.

The former behaviour is typical when hunting non-schooling fish, slow-moving or immobile invertebrates or endothermic prey. When large amounts of prey are available, whales such as certain mysticetes hunt cooperatively in small groups. Large whales, such as mysticetes, are not usually subject to predation, but smaller whales, such as monodontids or ziphiids, are.

These species are preyed on by the killer whale or orca. To subdue and kill whales, orcas continuously ram them with their heads; this can sometimes kill bowhead whales, or severely injure them. Other times they corral the narwhals or belugas before striking. They are typically hunted by groups of 10 or fewer orcas, but they are seldom attacked by an individual.

Calves are more commonly taken by orcas, but adults can be targeted as well. These small whales are also targeted by terrestrial and pagophilic predators. The polar bear is well adapted for hunting Arctic whales and calves. Bears are known to use sit-and-wait tactics as well as active stalking and pursuit of prey on ice or water.

Whales lessen the chance of predation by gathering in groups. This however means less room around the breathing hole as the ice slowly closes the gap. When out at sea, whales dive out of the reach of surface-hunting orcas. Polar bear attacks on belugas and narwhals are usually successful in winter, but rarely inflict any damage in summer. A study considered whales to be a positive influence to the productivity of ocean fisheries, in what has been termed a "whale pump. This functions as an upward biological pump, reversing an earlier presumption that whales accelerate the loss of nutrients to the bottom.

This nitrogen input in the Gulf of Maine is "more than the input of all rivers combined" emptying into the gulf, some 23, metric tons 25, short tons each year. The whale faeces are liquid and instead of sinking, they stay at the surface where phytoplankton feed off it. Upon death, whale carcasses fall to the deep ocean and provide a substantial habitat for marine life.

Evidence of whale falls in present-day and fossil records shows that deep sea whale falls support a rich assemblage of creatures, with a global diversity of species, comparable to other neritic biodiversity hotspots, such as cold seeps and hydrothermal vents.

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Deterioration of whale carcasses happens though a series of three stages. Initially, moving organisms such as sharks and hagfish , scavenge the soft tissues at a rapid rate over a period of months, and as long as two years. This is followed by the colonization of bones and surrounding sediments which contain organic matter by enrichment opportunists, such as crustaceans and polychaetes , throughout a period of years.

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Finally, sulfophilic bacteria reduce the bones releasing hydrogen sulfide enabling the growth of chemoautotrophic organisms, which in turn, support other organisms such as mussels, clams, limpets, and sea snails. This stage may last for decades and supports a rich assemblage of species, averaging species per site.

Whaling by humans has existed since the Stone Age. Ancient whalers used harpoons to spear the bigger animals from boats out at sea. The most successful whaling nations at this time were the Netherlands, Japan, and the United States.

Killer whale

Commercial whaling was historically important as an industry well throughout the 17th, 18th and 19th centuries. Whaling was at that time a sizeable European industry with ships from Britain, France, Spain, Denmark, the Netherlands and Germany, sometimes collaborating to hunt whales in the Arctic, sometimes in competition leading even to war.

The scale of whale harvesting decreased substantially after when the International Whaling Commission IWC placed a moratorium which set a catch limit for each country, excluding aboriginal groups until Current whaling nations are Norway, Iceland, and Japan, despite their joining to the IWC , as well as the aboriginal communities of Siberia, Alaska, and northern Canada.

National and international authorities have given special treatment to aboriginal hunters since their methods of hunting are seen as less destructive and wasteful.

This distinction is being questioned as these aboriginal groups are using more modern weaponry and mechanized transport to hunt with, and are selling whale products in the marketplace. Some anthropologists argue that the term "subsistence" should also apply to these cash-based exchanges as long as they take place within local production and consumption.

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Whales can also be threatened by humans more indirectly. They are unintentionally caught in fishing nets by commercial fisheries as bycatch and accidentally swallow fishing hooks. Gillnetting and Seine netting is a significant cause of mortality in whales and other marine mammals.

Whales are also affected by marine pollution. High levels of organic chemicals accumulate in these animals since they are high in the food chain. They have large reserves of blubber, more so for toothed whales as they are higher up the food chain than baleen whales. Lactating mothers can pass the toxins on to their young. These pollutants can cause gastrointestinal cancers and greater vulnerability to infectious diseases. Sonar interferes with the basic biological functions of whales—such as feeding and mating—by impacting their ability to echolocate.

Whales swim in response to sonar and sometimes experience decompression sickness due to rapid changes in depth. Mass strandings have been triggered by sonar activity, resulting in injury or death. Whaling decreased substantially after when, in response to the steep decline in whale populations, the International Whaling Commission placed a moratorium which set a catch limit for each country; this excluded aboriginal groups up until Vincent and the Grenadines each year. Conversely, the North Atlantic right whale was extirpated from much of its former range, which stretched across the North Atlantic, and only remains in small fragments along the coast of Canada, Greenland, and is considered functionally extinct along the European coastline.

Any nation may leave as they wish; the IWC cannot enforce any law it makes. Six are considered at risk, as they are ranked Critically Endangered the North Atlantic right whale , " Endangered " blue whale, fin whale, North Pacific right whale, and sei whale , and " Vulnerable " sperm whale. Twenty-one species have a " Data Deficient " ranking. An estimated 13 million people went whale watching globally in , in all oceans except the Arctic.

Whales and Dolphins: Behavior, Biology and Distribution Whales and Dolphins: Behavior, Biology and Distribution
Whales and Dolphins: Behavior, Biology and Distribution Whales and Dolphins: Behavior, Biology and Distribution
Whales and Dolphins: Behavior, Biology and Distribution Whales and Dolphins: Behavior, Biology and Distribution
Whales and Dolphins: Behavior, Biology and Distribution Whales and Dolphins: Behavior, Biology and Distribution
Whales and Dolphins: Behavior, Biology and Distribution Whales and Dolphins: Behavior, Biology and Distribution

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