Marine mammals are water-dependent marine mammals and other marine ecosystems for their existence. They include animals such as seals, whales, manatees, sea otters, and polar bears. They do not represent a different taxon or systematic grouping, but rather have polyphyletic relationships because of convergent evolution, because they have no common ancestors. They are also united by their dependence on the marine environment to eat.
Adaptation of marine mammals to aquatic lifestyles varies greatly among species. Cetaceans and sirens are wholly aquatic and therefore compulsory water dwellers. Seals and sea lions are semiotic; they spend most of their time in the water, but must return to the ground for important activities such as mating, breeding and skin changing. In contrast, beavers and polar bears much less adapt to aquatic life. Their food varies greatly; some people may eat zooplankton, others may eat fish, squid, shellfish, seaweed and some may eat other mammals. While the number of small marine mammals compared to those found on land, their role in various ecosystems is huge, especially regarding the maintenance of marine ecosystems, through processes including the setting of prey populations. This role in maintaining the ecosystem makes them a special concern because 23% of marine mammal species are currently threatened.
Marine mammals were first hunted by aborigines for food and other resources. Many are also targets for the commercial industry, leading to a sharp decline in all populations of exploited species, such as whales and seals. Commercial hunting led to the extinction of Steller's sea cow and the seal of Caribbean monks. After commercial hunting has ended, several species, such as gray whales and northern elephants, have recovered in numbers; on the contrary, other species, such as the North Atlantic whale, are highly threatened. In addition to hunting, marine mammals can be killed as bycatch from fisheries, where they are entangled in fixed nets and drowned or starved. Increased sea traffic causes a collision between fast ships and large marine mammals. Habitat degradation also threatens marine mammals and their ability to find and capture food. Sound pollution, for example, can affect mammals that do ecolocation, and the ongoing effects of global warming will degrade the arctic environment.
Video Marine mammal
Taxonomy
The classification of extant species
- Message Cetartiodactyla
- Suborder Whippomorpha
- The Balaenidae family (right whale and bow head), two genera and four species
- Family of Cetotheriidae (pygmy right whale), one species
- The Balaenopteridae family (rorquals), two genera and eight species
- Family Eschrichtiidae (gray whale), one species
- Family Physeteridae (sperm whale), one species
- The Kogiidae family (stunted and dwarfed sperm whales), one genus and two species
- The Monodontidae family (narwhal and beluga), two genera and two species
- Family Ziphiidae (half whale), six genera, and 21 species
- The Delphinidae family (ocean dolphins), 17 genera and 38 species
- The Phocoenidae family (porpoises), two genera and seven species
- Suborder Whippomorpha
- Message Sirenia (sea cow)
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- The Trichechidae family (manate), two species
- The Dugongidae family (dugong), one species
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- Carnivora (carnivore) message
- Subordo Caniformia
- The family of Mustelidae, three species
- The Ursidae family (bear), one species
- Pasteipedia suborder (seal, walrus, seal)
- Family Otariidae (ears seal), seven genera and 15 species
- The Odobenidae family (walrus), one species
- Family Phocidae (earless seal), 14 genera and 18 species
- Subordo Caniformia
- Chiroptera message
- The Vespertilionidae Family
- Myotis vivesi (fish-eating bats)
Evolution - The Vespertilionidae Family
- Cetaceans
- Pinnipeds
- Otter
- Sirenians
- Aquatic animals
- List of semiaquatic tetrapods
- Perrin, W. F.; Wursig, B.; Thewissen, J. G. M. (2009). Sea Mammal Encyclopedia (2nd ed.). San Diego: Academic Press. ISBN 978-0-0809-1993-5. OCLCÃ, 316226747. Ã,
- Center of Marine Mammals Conservation groups that focus on marine mammals
- Society for Marine Mammals The largest organization of marine mammal in the world.
- MarineBio Conservation Society An online education site on marine life
- National Oceanographic and Atmospheric Administration An agency that focuses on ocean and climatic conditions
- Introduction to Desmostylia Paleontology Museum , University of California - extinct marine mammal group
Marine mammals form a diverse group of 129 species that depend on the ocean for their existence. They do not represent a different taxon or systematic grouping, but have polyphyletic relationships. They are also united by their dependence on the marine environment to eat. Despite the apparent morphological diversity between groups, improved feeding efficiency has been a key driver in their evolution. The degree of dependence on the marine environment for existence varies with species. For example, dolphins and whales are entirely dependent on the marine environment for all stages of their lives; feed seals in the sea but breed on land; and polar bears have to eat on land. Twenty-three percent of marine mammal species are threatened.
Cetaceans became aquatic about 50 million years ago (mya). Based on molecular and morphological studies, cetaceans are genetically and morphologically falling strongly in Artiodactyla (ending ungulates). The term "Cetartiodactyla" reflects the idea that whales evolved within ungulates. The term was coined by combining names for two orders, Cetacea and Artiodactyla, into one word. Based on this definition, close relatives of dolphins and dolphins are considered hippopotamus.
Sirenian, seaweed, became aquatic about 40 million years ago. The first appearance of the siren in the fossil record was during the early Eocene period, and in the late Eocene, sirens were significantly diversified. Residents of the river, the estuary, and the waters of the seas near the coast, they can spread rapidly. The most primitive Sirenis, Prorastomus , are found in Jamaica, unlike other marine mammals that originate from the Old World (such as cetacea). The first known quadrupedal sirenia is Pezosiren from the beginning of Eocene. The earliest known seaweed, of the Prorastomidae and Protosirenidae families, are both limited to Eocene, and are pigs, four legs, and amphibians. The first member of the Dugongidae appeared in the late Eocene period. At this point, the cows are fully aquatic.
Pinnip separates from other caniforms 50 mya during Eocene. Their evolutionary relationship with terrestrial mammals was not known until the discovery of the 2007 Puijila darwini at the beginning of the Miocene deposit in Nunavut, Canada. Like a modern beaver, Puijila has a long tail, short limbs and webbed feet instead of fins. The Otariidae lineage (enlarged seal) and Odobenidae (walrus) are almost 28 mya. Phocids (earless seals) are known to have existed at least 15 mya, and molecular evidence supports the divergence of monachinae (monk seal) and the 22 mya Phocinae lineage.
The fossil evidence shows the sea-beavers ( Enhydra ) isolated in the North Pacific about two mya, resulting in extinction Enhydra macrodonta modern marine, Enhydra lutris . The sea otter evolved originally in northern Hokkaid? and Russia, and then spread to the east to the Aleutian Islands, the mainland of Alaska, and along the coast of North America. Compared to cetaceans, sirenians, and pinnipeds, which enter water about 50, 40, and 20 mya, respectively, sea otters are newcomers relative to marine life. In some respects, sea otters more fully adapt to water than pinnips, which must transport land or ice to give birth.
The polar bear is thought to have deviated from the brown bear population, Ursus arctos , which becomes isolated during the glaciation period in the Pleistocene or from eastern Siberia, (from Kamchatka and Kolym Peninsula)). The oldest known polar bear fossils are 130,000 to 110,000 years old jawbone, found at Prince Charles Foreland in 2004. Mitochondrial DNA (mtDNA) from polar bears deviates from brown bears about 150,000 years ago. Furthermore, some clade brown bears, as judged by their mtDNA, are more closely related to polar bears than other brown bear, meaning that polar bears may not be considered species under some species concept.
In general, marine terrestrial amniote invasion has become more common in Kenozoic than in Mesozoic. Factors contributing to this trend include increased productivity of the near-shore marine environment, and the role of endothermy in facilitating this transition.
Maps Marine mammal
Distribution and habitat
Marine mammals are widespread throughout the world, but their distribution is uneven and coincides with the productivity of the oceans. The species richness peaks at about 40 degrees latitude, either north or south. This corresponds to the highest primary production rates in North and South America, Africa, Asia and Australia. The total range of species varies greatly for species of marine mammals. On average most marine mammals have ranges that are equal to or less than one fifth of the Indian Ocean. The observed variation in range size is the result of different ecological requirements of each species and their ability to cope with various environmental conditions. The high level of overlap between the richness of marine mammal species and the area of ​​human impact on the environment is of concern.
Most marine mammals, such as seals and sea otters, inhabit the coast. Seals, however, also use a number of terrestrial habitats, both continents and islands. In temperate and tropical regions, they transport to sandy and pebbled beaches, rocky beaches, shoals, mud plains, tide pools and sea caves. Some species also depend on man-made structures, such as docks, piers, buoys and oil bases. Seals can move further inland and rest in sand dunes or vegetation, and even climb the cliffs. Most cetaceans live in open ocean, and species such as sperm whales can dive to a depth of -1,000 to -2,500 feet (-300 to -760 m) for food. Sirenians live in shallow coastal waters, usually living 30 feet (9.1 m) below sea level. However, they have been known to dive to -120 feet (-37 m) to search for deep water burrows. Sea otters live in protected areas, such as rocky beaches, seaweed forests, and barrier reefs, although they may be among the floating ice or in sandy, muddy, or muddy areas.
Many marine mammals migrate seasonally. The annual ice contains an area of ​​water that appears and disappears throughout the year as weather changes, and the seals migrate in response to these changes. In turn, polar bears must follow their prey. In Hudson Bay, James Bay, and several other areas, the ice melts completely every summer (an event often referred to as "the breakup of pumice ice"), forcing the polar bear to go ashore and wait for months until the next freeze. up. In Chukchi and Beaufort sea, polar bears retreat each summer to the ice in the north that remains frozen all year round. Seals also migrate to other environmental changes, such as El NiÃÆ' Â ± o, and travel seals can use their various environmental features to achieve their goals including geomagnetic, water and wind, sun and moon positions and taste and water temperature. The famous Baleen whales migrate great distances into tropical waters to give birth and raise children, perhaps to prevent predation by killer whales. Gray whales have the longest migration records of any mammal, with a single journey of 14,000 miles (23,000 km) from the Okhotsk Sea to the Baja Peninsula. During the winter, the manatees living at the northern end of their range migrate to warmer waters.
Adaptations
Marine mammals have a number of physiological and anatomical features to address the unique challenges associated with aquatic life. Some of these features are very specific. Marine mammals have developed a number of features for efficient drivers such as torpedo-shaped bodies to reduce barriers; modified limbs for propulsion and steering; tail flukes and dorsal fins for propulsion and balance. Marine mammals are proficient in thermoregulation using dense or fat bristles, circulation adjustments (counter-current heat exchangers); torpedo-shaped bodies, reduced appendages, and large sizes to prevent heat loss.
Marine mammals are able to dive for long periods of time. Both pinnipeds and cetaceans have large and complex vascular systems that serve to store oxygen to support deep dives. Other important reservoirs include muscle, blood, and spleen all of which have the capacity to withstand high oxygen concentrations. They are also capable of bradycardia (reduced heart rate), and vasoconstriction (removing most of the oxygen to vital organs such as brain and heart) to allow longer dive time and overcome oxygen deprivation. If oxygen is depleted, marine mammals can access large glycogen reservoirs that support anaerobic glycolysis of the cells involved during systemic hypoxic conditions associated with prolonged immersion.
Voice runs differently through water, and hence marine mammals have developed adaptations to ensure effective communication, capture prey, and detect predators. The most important adaptation is the development of ecolocation on whales and dolphins. Toothed whales emit the focus of a high-frequency click in the direction directed by their head. Sound is generated by passing air from the bone nares through the phonic lips. These sounds are reflected by the concave bones of the skull and the air sacs at the bottom. The focused beam is modulated by a large fat organ known as the 'melon'. It acts like an acoustic lens because it consists of lipids of different densities.
Marine mammals have evolved various features to feed, especially seen in their teeth. For example, pinnip cheek teeth and odontocetes are specially adapted for catching fish and squid. In contrast, baleen whales have evolved baleen plates to filter plankton feed and small fish from water.
Polar bears, beavers and fur seals have feathers, one of the defining characteristics of a long, oily, waterproof mammal to trap air to provide insulation. In contrast, other marine mammals - such as whales, dolphins, sea dolphins, manates, dugongs, and walruses - have lost long hair because of thick and thick epidermal layers and fatty (fat) fatty layers in response to hydrodynamic requirements. Animals that sail and feed below (such as manate) should be heavier than water to keep contact with the floor or stay submerged. Surface animals (like sea otters) need the opposite, and free-swimming animals that live in open water (such as dolphins) must be able to float neutrally in order to swim up and down the water column. Typically, thick and solid bones are found under low feeders and bone density is associated with mammals that live in deep water. Some marine mammals, such as polar bears and beavers, have held four weight-bearing limbs and can walk ashore as fully ground animals.
Ecology
Diet
All cetaceans are carnivores and predators. Most-toothed whales feed on fish and cephalopods, followed by crustaceans and bivalves. Some may find feeding with other types of animals, such as other whale species or certain pinniped species. One common method of feeding is herding, in which the pod squeezes a fish school into a small volume, known as ball bait. The individual members then take turns hijacking the ball, feeding on the astonished fish. Coralling is the method by which dolphins chase fish into shallow water to catch them more easily. Killer whales and bottlenose dolphins are also known to ride their prey to the beach to eat it. Other whales with blunt snouts and reduced tooth growth depend on suctioning. Despite the carnivores, they have a flora similar to terrestrial herbivores, probably the remains of their herbivorous ancestors.
Baleen whales use their baleen plates to sift the plankton, inter alia, out of the water; there are two types of methods: lunge-feeding and gulp-feeding. The lunge feeders extend the volume of their jaws to a volume greater than the original volume of the whale itself by inflating their mouths. This causes the grooves in their throats to expand, increasing the amount of water that can be stored mouth. They hit a feed bait at high speed to feed, but this is only energy efficient when used against large baits. Gulp-feeder swims with his mouth open, fills it with water and prey. The prey must occur in sufficient quantities to spark the whale's interest, within a certain size range so that the baleen plate can filter it, and slow enough that it can not escape.
Beavers are the only marine animals capable of lifting and turning stones, which they often do with the front paws when looking for prey. Sea otters can pick snails and other organisms from seaweed and dig deep into underwater mud for shells. It is the only marine mammal that catches fish with forepaws rather than with its teeth. Below each other's front legs, the sea otters have loose leather pouches that extend across the chest they use to store the collected food to be brought to the surface. The pouch also holds stones used to break open shells and shells, eg the use of tools. The sea otters eat while floating on their backs, using their front paws to tear the food and bring it to their mouths. Sea otters mainly eat crustaceans and fish.
Pinniped mostly eat fish and cephalopods, followed by crustaceans and bivalves, and then zooplankton and hot-blooded prey (like seabirds). Most species are generalist feeders, but some are specialists. They usually hunt non-school fish, slow-moving or immobile invertebrates or endothermic prey as a group. Species for solitary feeding usually exploit coastal waters, bays and rivers. When large schools of fish or squid are available, pinnip hunts cooperatively in large groups, finding and herding their prey. Some species, such as California and South American sea lions, may be feeding with cetaceans and seabirds.
Polar bears are the most abundant species of carnivorous bears, and the diet consists primarily of the ring ( Pusa hispida ) and the beard ( Erignathus barbatus ) seal. Polar bears hunt primarily at the interface between ice, water, and air; they seldom catch seals on land or in open water. The most common method of hunting polar bears is still hunting: The bear places the seal breathing hole using its sense of smell, and bends nearby for the seal to appear. When the seal exhaled, the bear kissed his breath, reached the hole with the forepaw, and dragged it out onto the ice. Polar bears also hunt by lurking seals that are resting on the ice. After finding the seal, it runs into 100 meters (90 m), and then bends down. If the seal is not noticed, the bear creeps within 30 to 40 feet (9 to 10 m) of the seal and then suddenly rushes to attack. The third hunting method is attacking the birth nest that the female dog made in the snow. They may also eat fish.
Sirenians are referred to as "sea cows" because their diet consists mainly of seaweed. When eating, they swallow whole plants, including roots, although at present it is unlikely they only eat the leaves. Various kinds of seagrasses have been found in the contents of dugong belly, and there is evidence they will eat algae when seagrass is rare. West Indian Manate feeds up to 60 different species of plants, as well as small fish and invertebrates to lower levels.
Keystone species
Sea otter is a classic example of a key species; Their presence affects ecosystems deeper than their size and number. They maintain a population of certain benthic herbivores (seafloor), especially sea urchins, in checks. The sea urchins graze on the stalks of the seaweed, causing the seaweed to drift and die. The loss of habitat and nutrients provided by seaweed forests causes a deep cascade effect on marine ecosystems. North Pacific regions that do not have sea otters often turn into porcupine hedgehogs, with abundant sea urchins and no seaweed forests. The reintroduction of sea otters to British Columbia has led to a dramatic increase in the health of coastal ecosystems, and similar changes have been observed when sea otter populations recovered in the Aleutian and Commander Islands and the Big Sur coast of California. However, some marine forest ecosystems in California are also growing without sea otters, with sea urchin populations apparently controlled by other factors. The role of sea otters in maintaining the forest kelp has been observed to be more important in open coastal areas than in more protected bays and estuaries.
The peak predator influences the dynamics of prey populations and defense tactics (such as camouflage). Polar bears are the top predators in their reach. Some animal species, especially the Arctic fox ( Vulpes lagopus ) and glaucus gulls ( Larus hiperboreus ), routinely scavenge killing polar bears. The relationship between seals ringed and polar bears is so close that the abundance of ring seals in some areas seems to regulate the polar bear density, while polar bear predation in turn governs the density and reproductive success of ringed seals. The evolutionary pressure of polar bear predation on seals may contribute some significant differences between Arctic and Antarctic seals. Compared to Antarctica, where no predominant surface predators, the Arctic seal uses more respiratory holes per individual, appears more agitated when pulled out on the ice, and rarely defecates on ice. Arctic children's fur is white, probably to give camouflage from predators, while Antarctic rats all have dark hairs.
Killer whales are the top predators throughout their global distribution, and can have profound effects on the behavior and populations of prey species. Their food is very extensive and they can eat many vertebrates in the sea including salmon, rays, sharks (even white sharks), large baleen whales, and nearly 20 pinniped species. Whale child predation may be responsible for annual whale migration to where calving in more tropical waters, where killer whale populations are much lower than in polar waters. Prior to whaling, it was thought that large whales were a major food source; However, after their sharp decline, killer whales have expanded their diets, leading to a decrease in smaller marine mammals. The decline in sea otters population of the Aleutian Islands in the 1990s is controversially attributed by some scientists to the predation of whaling killers, albeit without direct evidence. The deterioration of sea otters was accompanied by a decline in seal ports and the population of Steller's sea lions, the preferred prey of killer whales, which in turn may be a substitute for their original prey, which is now reduced due to whale hunting.
Whale pump
A 2010 study considered the whales as a positive influence on marine fisheries productivity, referred to as "whale pumps". Whales carry nutrients like nitrogen from the depths back to the surface. It serves as an upward biological pump, reversing a previous notion that whales accelerate the loss of nutrients to the bottom. The nitrogen input in the Bay of Maine is more than the input of all rivers emptied into the bay, about 25,000 short tons (23,000 tons) every year. Whales defecate at sea level; Their impurities are important for fisheries because they are rich in iron and nitrogen. Whale dung is liquid rather than drowning, they live on the surface where phytoplankton eats it.
After death, whale carcasses fall into the deep sea and provide a substantial habitat for marine life. Current papal evidence falls and the fossil record shows that deepwater whales support a rich collection of creatures, with a global diversity of 407 species, comparable to other nerritic biodiversity hotspots, such as cold seepage and hydrothermal vents. Whale damage occurs through a series of three stages. Initially, moving organisms, such as sharks and hagfish, scavenged soft tissue at a rapid rate for several months up to two years. This is followed by bone colonization and surrounding sediments (containing organic matter) by enrichment opportunists, such as crustaceans and polychaetes, for several years. Finally, sulfophilic bacteria reduce bone release of hydrogen sulphide allows the growth of chemoautotrophic organisms, which in turn, supports other organisms such as shell, shell, limpet, and sea slugs. This stage can last for decades and support a rich collection of species, an average of 185 species per site.
Interaction with humans
Threat
Exploit
Marine mammals are hunted by coastal inhabitants historically for food and other resources. These subsistence hunts still occur in Canada, Greenland, Indonesia, Russia, the United States, and some Caribbean countries. The effect of this is only localized, due to hunting efforts on a relatively small scale. Commercial hunting takes this to a much larger scale and marine mammals are heavily exploited. This led to the extinction of Steller's sea cow (along with subsistence hunting) and the seal of Caribbean monks. Today, historically hunted species populations, such as the blue whale ( Balaenoptera musculus ) and the right North Pacific whale ( Eubalaena japonica ), are much lower than pre-whale levels. Because whales generally have slow growth rates, are slow to reach sexual maturity, and have low reproductive output, population recovery is very slow.
A number of whales are still subject to direct hunting, despite the 1986 ban on whaling under the provisions of the International Whaling Commission (IWC). There are only two countries left to sanction commercial whaling: Norway, where several hundred minke whales are commonly harvested every year; and Iceland, where the quota of 150 fin whales and 100 minke whales per year are set. Japan also harvests several hundred Antarctic and North Pacific minke whales every year, as if for scientific research in accordance with the moratorium. However, the illegal trade in whale and dolphin meat is a significant market in Japan and some countries.
The most feathery feathers in the feather trade are the sea-octopus fur, especially the northern sea otter who inhabit the coastal waters between the Columbia River to the south and Cook Inlet to the north. The feathers of California's southern octopus are poorly valued and therefore less profitable. After the north sea otter hunted to local extinction, maritime fur traders shifted to California until the southern otters were also extinct. British and American maritime fur traders carry their fur to Guangzhou's Guangzhou port (Canton), where they work in established Canton Systems. The feathers of American Russia are largely sold to China through the trade town of Mongolia Kyakhta, which has been opened for Russian trade by the 1727 Kyakhta Agreement.
Commercial sealing is historically as important as the whaling industry. Exploited species include harp seal, hooded seal, Caspian seal, sea elephant, walrus and all species of seals. The sealing scale of the seals decreased substantially after the 1960s, after the Canadian government reduced the length of the hunting season and implemented measures to protect adult females. Some commercially exploited species have increased in number; for example, Antarctic seals may be as much as before harvest. Northern elephant seals were hunted until almost extinct at the end of the 19th century, with only a small population remaining on Guadalupe Island. Since then, the region has undergone a lot of recolonization, but has population constraints. In contrast, the seal of Mediterranean monks has become extinct from most of the previous reach, which stretches from the Mediterranean to the Black Sea and northwest Africa, and only remains in the northeast Mediterranean and some parts of northwest Africa.
Polar bears can be hunted for sport in Canada with special permission and accompanied by local guides. This can be an important source of income for small communities, since guided hunting generates more revenue than selling polar bears on the market. The United States, Russia, Norway, Greenland, and Canada allow subsistence hunting, and Canada distributes hunting licenses to indigenous peoples. The sale of these licenses is a major source of income for many of these communities. Their hides can be used for subsistence purposes, stored as hunting trophies, or can be bought in the market.
Sea traffic and fishery
By-catch is the incidental capture of non-target species in the fishery. Fixed and drifting gill nets cause the highest mortality rates for both cetaceans and pinnip, however, shackles in long lines, seine trawls, and both trap and potted pathways are also common. Tuna seina is very problematic for dolphins by dolphins. By-catch affects all cetaceans, both small and large, in all habitat types. However, smaller and pinniped cetaceans are most vulnerable because their size means that escaping after being entangled is highly unlikely and they are often drowned. While larger cetaceans are able to drag nets with them, nets sometimes adhere closely to the individual and may prevent animals from feeding sometimes leading to starvation. Missing or missing webs and paths cause death through consumption or winding. Marine mammals are also entangled in aquaculture webs, however, this is a rare occurrence and is not common enough to affect the population.
The strike ship caused death for a number of marine mammals, especially whales. In particular, rapid commercial vessels such as container ships can cause major injury or death when they collide with marine mammals. Collisions occur both with large commercial vessels and recreational boats and causing injuries to smaller whales or cetaceans. The highly endangered North Atlantic whale is mainly affected by ship attacks. Tour boats designed to observe whales and dolphins can also have a negative impact on marine mammals by disrupting their natural behavior.
The fishing industry not only threatens marine mammals through side catching, but also through competition for food. Large-scale fisheries have led to depletion of fish stocks that are important prey species for marine mammals. Pinniped is primarily affected by the loss of food supplies directly and in some cases fish harvesting has led to food shortages or food shortages, starvation, and reduced recruitment into the population. As fish stocks have run out, competition between marine mammals and fisheries sometimes causes conflict. The massive destruction of marine mammal populations by commercial fishermen has begun in some areas to protect fish stocks for human consumption.
Aquaculture shells eat up space thus creating competition for space. However, there is little direct competition to harvest aquaculture shells. On the other hand, marine mammals regularly take fish from farms, which creates significant problems for marine farmers. Although there is usually a legal mechanism designed to deter marine mammals, such as anti-predator nets or harassment devices, individuals are often shot illegally.
Habitat loss and degradation
Habitat degradation is caused by a number of human activities. Marine mammals living in coastal environments are likely to be affected by degradation and habitat loss. Developments such as marine waste disposal, mooring, dredging, blasting, disposal, port development, hydroelectric projects, and aquaculture damage the environment and take valuable habitats. For example, extensive shellfish cultivation takes up valuable space used by coastal marine mammals for important activities such as nurseries, foraging and resting.
Contaminants that are dumped into the marine environment accumulate in the bodies of marine mammals when they are accidentally stored in their fat along with energy. Contaminants found in marine mammal tissues include heavy metals, such as mercury and lead, but also polycyclic aromatic organochlorides and hydrocarbons. For example, this may cause disturbing effects on the endocrine system; damaging the reproductive system, and decreasing the individual's immune system, leading to higher death counts. Other pollutants such as oil, plastic debris and waste threaten the livelihoods of marine mammals.
Sound pollution from anthropogenic activity is also a major concern for marine mammals. This is a problem because underwater noise pollution interferes with the ability of some marine mammals to communicate, and finds predators and prey. Underwater explosions are used for a variety of purposes including military activities, construction and oceanographic or geophysical research. They can cause injuries such as lung bleeding, and bruising and ulceration of the gastrointestinal tract. Underwater sounds are generated from shipments, oil and gas industries, research, and military use of sonar and oceanographic acoustic experiments. Acoustic detection devices and acoustic deterrent devices used by aquaculture facilities to frighten marine mammals create harsh and dangerous underwater sounds.
Two changes in the global atmosphere due to anthropogenic activity threaten marine mammals. The first is the increase in ultraviolet radiation due to ozone depletion, and this mainly affects Antarctica and other areas of the southern hemisphere. Increased ultraviolet radiation has the ability to reduce the abundance of phytoplankton, which forms the basis of the food chain in the oceans. The second effect of global climate change is global warming due to increased levels of carbon dioxide in the atmosphere. Sea level rise, changing sea temperatures and currents are expected to affect marine mammals by altering the distribution of important prey species, and altering the suitability of breeding sites and migration routes. The Arctic food chain will be disturbed by near extinction or polar bear migration. Arctic sea ice is the habitat of polar bears. It has declined at a rate of 13% per decade as the temperature has doubled from the world-wide level. By 2050, up to two-thirds of the world's polar bears may disappear if sea ice continues to melt at the current rate.
Protection
The Marine Mammal Protection Act of 1972 (MMPA) was adopted on 21 October 1972 under President Richard Nixon to prevent further depletion and possible extinction of marine mammal stocks. It prohibits taking ("the act of hunting, killing, capturing, and/or harassing marine mammals, or, such attempts") of unauthorized marine mammals issued by the Secretary. The authority to administer the MMPA is shared between the Interior Secretary through the US Fish and Wildlife Services and Services, and the Minister of Commerce, delegated to the National Oceanic and Atmospheric Administration (NOAA). The Marine Mammal Commission (MMC) was established to review existing policies and make recommendations to the Service and NOAA to implement the MMPA better. The service is responsible for ensuring the protection of sea otters and sea otters, walruses, polar bears, three species of manatees, and dugongs; and NOAA was given the responsibility to preserve and manage pinnipeds (not including walruses) and cetaceans.
The 1979 Convention on the Conservation of Wilderness Species of Wildlife Species (CMS) is the only global organization that conserves a variety of animals, including marine mammals. Of the agreements made, three of them dealt with marine mammal conservation: ACCOBAMS, ASCOBANS, and the Wadden Sea Treaty. In 1982, the United Nations Convention on the Law of the Sea (LOSC) adopted a pollution prevention approach to conservation, which many other conventions were also adopted at the time.
The Treaty on the Conservation of Cetaceans in the Black Sea, the Mediterranean Sea and adjacent Atlantic areas (ACCOBAMS), established in 1996, specifically protects cetaceans in the Mediterranean region, and "maintains good status", direct action on whaling. There are 23 member states. The Agreement on the Conservation of Small Cetaceans in the Baltic and North Seas (ASCOBANS) was adopted with ACCOBAMS to build a special protection zone for the increasingly threatened European cetaceans. Other anti-whaling efforts include a ten-year moratorium in 1986 by the IWC on all whaling, and environmental agreements (a type of international law) of the International Convention for Whaling Regulations that control commercial, scientific, and subsistence fishing.
The Agreement on Seal Conservation in the Wadden Sea, enacted in 1991, prohibits the killing or harassment of seals in the Wadden Sea, in particular targeting seal harbor populations.
The 1973 Agreement on the Conservation of Polar Bears between Canada, Denmark (Greenland), Norway (Svalbard), the United States, and the Soviet Union prohibit unmanned polar bear hunting of planes and ice breakers, and protect migration, feeding, and hibernation sites.
Various non-governmental organizations participate in marine conservation activism, where they attract attention and assist in various issues in marine conservation, such as pollution, whaling, bycatch, and so on. Leading organizations include Greenpeace which focuses on overfishing and whaling among other things, and the Sea Shepherd Conservation Society is known for taking direct action tactics to expose illegal activities.
As food
For thousands of years, the indigenous Arctic has depended on whale meat. Meat is harvested from legal and non-commercial hunting that occurs twice a year in spring and autumn. Meat is stored and eaten throughout the winter. Skin and fat (muktuk) taken from the head of the bow, beluga, or narwhal are also appreciated, and eaten raw or cooked. Whaling has also been practiced in the Faroe Islands in the North Atlantic since around the time of the first Norse settlement on the islands. About 1,000 long-finned pilot whales are still killed every year, especially during the summer. Today, dolphin meat is consumed in a small number of countries around the world, including Japan and Peru (where it is referred to as chancho marino, or "sea pig"). In some parts of the world, such as Taiji, Japan, and the Faroe Islands, dolphins are traditionally regarded as food, and killed in harpoon or hunting.
There are human health problems associated with the consumption of dolphins in Japan after tests show that dolphins contain high levels of methylmercury. No cases of mercury poisoning are known to result from eating dolphin meat, although the government continues to monitor people in areas where meat consumption of dolphins is high. The Japanese government recommends that children and pregnant women avoid eating dolphins regularly. Similar concerns arise with the consumption of dolphins in the Faroe Islands, where prenatal exposure to methylmercury and PCBs primarily from pilot whale consumption has resulted in neuropsychological deficits among children.
The Faroe Islands population is exposed to methylmercury mostly from contaminated pilot whales, which contain very high levels of about 2 mg methylmercury/kg. However, the Faroe Islands population also eats fish in significant amounts. The study of 900 Faroese children showed that prenatal exposure to methylmercury resulted in neuropsychological deficits at 7 years of age
Sealed dogs were once the main staple food for the Inuit. They are still an important food source for the Nunavut people and are also hunted and eaten in Alaska. The meat seal is an important food source for small coastal populations. Seal blubber is used to make oil seals, which are marketed as fish oil supplements. In 2001, two percent of Canadian seal crude oil was processed and sold at Canadian health stores.
In captivity
Aquarium
Various species of dolphins are kept in captivity. These small cetaceans are more often stored in amusement parks and dolphinariums, such as SeaWorld. Bottlenose dolphins are the most common dolphin species stored in the dolphinarium because they are relatively easy to train and have long life in captivity. Hundreds of bottlenose dolphins live in captivity all over the world, though numbers must be difficult to determine. Dolphin's "smile" makes them popular, because it is a human-friendly expression; But the smile was due to the lack of facial muscles and the lack of subsequent facial expression.
Organizations such as the World Animal Protection and the Pope and Dolphin Conservation Society campaign against the practice of guarding cetaceans, especially killer whales, are in captivity. In captivity, they often develop pathology, such as the collapse of the dorsal fin seen in 60-90% of male killer whales. Prisoners have greatly reduced life expectancy, on average live only in their 20s. In the wild, females survive for 46 years on average, and up to 70-80 years in rare cases. Wild men who survive babies live 31 years on average, and up to 50-60 years old. Captive breeding usually has little resemblance to wild habitats, and whale groups are foreign to those found in the wild. The captive life is also stressful because of the requirement to perform circus tricks that are not part of the behavior of wild killer whales, as well as limiting pool size. Wild whale killers can travel up to 100 miles (160 km) a day, and critics say the animals are too big and smart to be fit for captivity. Prisoners sometimes act aggressively against themselves, their tank friends, or humans, which critics say are the result of stress. Dolphins are often trained to perform some anthropomorphic behavior, including waving and kissing - the behavior of wild dolphins is rare.
The large size and playful pinnipeds make them a popular attraction. Some exhibits have rocky backdrops with artificial hauls and pools, while others have cages with small, rocky shelter and elevated where animals can dive into their ponds. A more elaborate exhibit contains an underwater pool that can be seen underwater with stone-like cement as a transport area. The most common pinnip species preserved in captivity are the California sea lions because they are abundant and easily trained. These animals are used to perform tricks and entertain visitors. Other species that are popular in captivity include the gray seal and port seals. Larger animals such as walruses and Steller's sea lions are much less frequent. Pinnipeds are a popular attraction because they are "disneyfied", and, consequently, people often anthropomorphize them with strange, funny, or playful traits.
Some organizations, such as the Humane Society of the United States and World Animal Protection, object to keeping pinnipeds and other marine mammals in captivity. They claimed that the exhibit could not be large enough to accommodate animals that had evolved to migrate, and that the pond could never replace the size and biodiversity of the oceans. They also oppose using sea lions for entertainment, claiming the tricks are "excessive variations of their natural behavior" and distracting the audience from an unnatural animal environment.
Sea otters can do well in captivity, and are featured in over 40 public aquariums and zoos. The Seattle Aquarium became the first institution to lift sea otters from conception to adulthood with the birth of Tichuk in 1979, followed by three more puppies in the early 1980s. In 2007, a YouTube video of two cute sea otters holding legs attracted 1.5 million viewers in two weeks, and had over 20 million views in January 2015. Filmed five years earlier at the Vancouver Aquarium, it was the most animal video popular on YouTube. time, although it has since been exceeded. Beavers are often considered to have "happy family life", but this is anthropomorphism.
The oldest manate in captivity is Snooty, at Manatee Manatee Aquarium at the South Florida Museum in Bradenton, Florida. Born at Miami Aquarium and Tackle Company on July 21, 1948, Snooty was one of the first recorded births of manatees. He grew up completely in captivity, and died at the age of 69 years. Manate can also be seen in a number of European zoos, such as Tierpark in Berlin, Nuremberg Zoo, at ZooParc de Beauval in France, and at the Aquarium of Genoa in Italy. The River Safari in Singapore has seven of them.
Military
Bottle nose dolphins and California sea lions are used in the Navy's Naval Naval Program (NMMP) to detect mines, protect ships from enemy soldiers, and recover objects. The Navy has never trained dolphin attacks, because they will not be able to distinguish the allied army from the enemy army. There are five teams of marine mammals, each aiming for one of three tasks: MK4 (dolphin), MK5 (sea lion), MK6 (dolphins and sea lions), MK7 (dolphins), and MK8 (dolphins -Dolphin); MK is short for mark. The dolphin team is trained to detect and mark the mines either sticking to the seabed or floating in the water column, because dolphins can use their echolocative ability to detect mines. The team of sea lions take test kits such as fake mines or bombs dropped from the plane usually outside the range of divers who have to make multiple dives. MK6 protects ports and ships from enemy divers, and operates in the Gulf War and Vietnam War. Dolphins will swim behind enemy divers and put a buoy into their air tank, so they will float to the surface and alert the nearest Navy personnel. Sea lions will handcuff the enemy, and try to surpass their counterattack.
The use of marine mammals by the Navy, even in accordance with the Navy's policies, continues to face opposition. The Navy's policy says that only positive reinforcement will be used when training military dolphins, and that they are being treated in accordance with accepted standards in animal care. The inevitable pressure involved in training is a topic of controversy, because their treatment is not like the natural lifestyle of animals, especially to their limited space when not trained. There is also controversy over the use of muzzles and other inhibitors, which prevent dolphins from finding food while working. The Navy stated that this was to prevent them from ingesting dangerous objects, but conservation activists say this was done to strengthen the coach control over the dolphins, who are distributing food rewards. Transportation facilities are also a problem for conservation activists, as they are transported by aircraft carriers dry, and changing tanks and introducing dolphins into new dolphins is potentially dangerous because they are territorial.
See also
References
Further reading
External links
Source of the article : Wikipedia
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