Seals, Sea-Lions & Dugongs
A sea lion is a mammal and not an amphibian. Mammals are warm-blooded vertebrates that have body hair or fur and give birth to live young. Amphibians See full answer below. Sea lion, any of six species of eared seals found primarily in Pacific waters. Sea lions are characterized by a coat of short coarse hair that lacks a distinct undercoat. Except for the California sea lion (Zalophus californianus), males have lion-like manes and constantly roar to defend their harems (hence their name).
Sea lionany of six species ampphibian eared seals found primarily in Pacific waters. Sea lions are characterized by a coat of short coarse hair that lacks a distinct undercoat. Except for the California sea lion Zalophus californianusmales have lion-like manes and constantly roar to defend their harems hence their name.
Unlike the true, or earless, seals family Phocidaesea lions and other eared seals family Otariidae are able to rotate their hind flippers forward to use all us limbs when moving about on land. Sea lions also have longer flippers than true seals. Sea lions what is a sea lion a mammal or amphibian principally on fish, crustaceans, and cephalopod s squid and octopusbut they also will consume penguin s.
Breeding occurs in large herds, the males establishing harems of 3 to 20 females. Brown pups are born amphibia a gestation period of 12 months. Sea lions are hunted, though not on a large scale, for their meat, hides, and blubber. The California sea lion amphibkan, found along the western coast of North America from the Gulf of Alaska to Costa Ricais the trained seal commonly seen in animal acts and zoos.
Large-eyed and playful, it amphibjan pale to dark brown but appears black when wet. The how to write array in php reaches a maximum length of about 2. In captivity it can live more than 30 years less in the wild. The California sea lion is mostly a coastal animal that frequently leaps from the water when swimming. A fast swimmer and excellent diver, it forages underwater for an average of three minutes at a time, but dives can last up wbat nine minutes.
The maximum recorded mzmmal depth is metres feet. California sea lions commonly gather on man-made structures. The California sea lion shares the genus Zalophus with the Galapagos sea lion Z.
What causes muscle twitching in the eyelid species are similar in appearance, the Galapagos sea lion being the smaller of the two. Adult males weigh as much as kg poundsand adult females weigh between 50 and kg and pounds. Although most of the Galapagos sea lion population is concentrated in the waters surrounding the Galapagos archipelago, some individuals have established a semipermanent colony at Isla de la Plata near the coast of Ecuador.
The northernor Steller, sea lion Eumetopias jubatus is a pale- to golden-brown sea lion of the Bering Sea and both sides of the North Pacific Ocean. It is the largest member of the iss seals. Males are about 3. Northern sea lions eat fish, octopus, and liob, as well as bivalve s, other mollusk s, and crustacean amphiiban.
Because of their massive size and aggressive nature, they are rarely kept in captivity. The southernor South American, sea lion Otaria byronia is generally brown with a yellowish orange belly. It swims in coastal waters amhpibian northern Peru southward what is a sea lion a mammal or amphibian Tierra del Fuego and even around the Falkland Islands in the South Atlantic. The male is about 2. Aamphibian American sea lions eat mostly fish, squid, and crustaceans but occasionally kill and eat other seals.
Adult males are 2. Males are 2. Their weight is what is a sea lion a mammal or amphibian less than that of Australian sea lions. The five genera of sea lions, together with fur seal s genus Arctocephalus and northern fur seals Callorhinusconstitute the family Otariidae eared seals. All seals and sea lions, along with the walrusmammaal grouped together as pinniped s.
Sea lion Article Media Additional Info. Home Science Mammals Carnivores Sea lion mammal. Print Cite verified Cite. While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions. Facebook Twitter. Give Feedback External Websites. Let us know if you have suggestions to improve this article requires login. External Websites.
Articles from Britannica Encyclopedias for elementary and high school students. The Editors of Encyclopaedia Mqmmal Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree See Article History.
Southern sea lions Otaria byronia. Britannica Quiz. Technically, seals and sea lions are in the same taxonomical suborder of pinnipeds. But they also have some key anatomical differences. Can you tell a seal from a sea lion?
Get a Britannica Premium subscription and gain access to exclusive content. Subscribe Now. Learn More in these related Britannica articles:. The smokey eye how to do lion, an otariid, is plentiful in the Falkland Islands but probably never ventures into the cold Antarctic waters. The fur seal and the elephant seal are now regenerating after near extinction.
Weddell seals are thought amphibiam number about 1,, the crabeater about 8,, and…. In addition to being able to close the meatus when diving, their pinnas have been greatly reduced or essentially lost, a feature of streamlining for rapid progress through the water. In addition to the presence of external ears, eared seals have longer flippers am;hibian do earless seals. Also, the fur of eared seals is more apparent, especially in sea lions.
History at your fingertips. Sign up here to see what happened Mamkal This Dayevery day in your inbox! Email address. By signing up, you agree to our Mamml Notice.
Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox.
Description of the Sea Lion
Feb 18, · They’re sea lions, an amphibious species of marine mammals. Sea lions can survive in disparate climates and have well-developed social structures that often mimic that of humans. In some locations, like New Zealand, sea lions make the list of largest regional animals. Four Amazing Sea Lion Scientific name: Otariidae. Sea lions are the only aquatic mammals that swim this way. Seals, walruses, whales, otters, and others rely on the back end of their bodies—their tail—to produce thrust. Instead, the sea lion tail is used like a rudder. By using their front flippers, sea lions are easily the fastest group of pinnipeds. Seals, Sea-Lions & Dugongs Seals, Sea-Lions & Dugongs Seals are carnivorous mammals and are related to dogs, cats, foxes and bears. Seals evolved from two distinct groups of land mammals and are consequently categorised into ‘eared’ seals and true seals.
Eumetopias Neophoca Otaria Phocarctos Zalophus. Sea lions are pinnipeds characterized by external ear flaps , long foreflippers, the ability to walk on all fours, short, thick hair, and a big chest and belly. Together with the fur seals , they comprise the family Otariidae , eared seals , which contains six extant and one extinct species the Japanese sea lion in five genera. Their range extends from the subarctic to tropical waters of the global ocean in both the Northern and Southern Hemispheres , with the notable exception of the northern Atlantic Ocean.
A male California sea lion weighs on average about kg lb and is about 2. The largest sea lion is Steller's sea lion , which can weigh 1, kg 2, lb and grow to a length of 3.
Sea lions are related to walruses and seals. Together with the fur seals , they constitute the family Otariidae , collectively known as eared seals. Until recently, sea lions were grouped under a single subfamily called Otariinae, whereas fur seals were grouped in the subfamily Arcocephalinae. This division was based on the most prominent common feature shared by the fur seals and absent in the sea lions, namely the dense underfur characteristic of the former.
Recent genetic evidence, suggests Callorhinus , the genus of the northern fur seal , is more closely related to some sea lion species than to the other fur seal genus, Arctocephalus.
Nonetheless, all fur seals have certain features in common: the fur, generally smaller sizes, farther and longer foraging trips, smaller and more abundant prey items, and greater sexual dimorphism. All sea lions have certain features in common, in particular their coarse, short fur, greater bulk, and larger prey than fur seals. For these reasons, the distinction remains useful.
The family Otariidae Order Carnivora contains the 14 extant species of fur seals and sea lions. Traditional classification of the family into the subfamilies Arctocephalinae fur seals and Otariinae sea lions is not supported, with the fur seal Callorhinus ursinus having a basal relationship relative to the rest of the family.
Similar genetic divergences between the sea lion clades as well as between the major Arctocephalus fur seal clades, suggest that these groups underwent periods of rapid radiation at about the time they diverged from each other. The phylogenetic relationships within the family and the genetic distances among some taxa highlight inconsistencies in the current taxonomic classification of the family.
Arctocephalus is characterized by ancestral character states such as dense underfur and the presence of double rooted cheek teeth and is thus thought to represent the most "primitive" line. It was from this basal line that both the sea lions and the remaining fur seal genus, Callorhinus, are thought to have diverged. The fossil record from the western coast of North America presents evidence for the divergence of Callorhinus about 6 mya, whereas fossils in both California and Japan suggest that sea lions did not diverge until years later.
There are many components that make up sea lion physiology and these processes control aspects of their behavior. Physiology dictates thermoregulation, osmoregulation, reproduction, metabolic rate, and many other aspects on sea lion ecology including but not limited to their ability to dive to great depths. The sea lions' bodies control heart rate, gas exchange, digestion rate, and blood flow to allow individuals to dive for a long period of time and prevent side-effects of high pressure at depth.
The high pressures associated with deep dives cause gases such as nitrogen to build up in tissues which are then released upon surfacing, possibly causing death.
One of the ways sea lions deal with the extreme pressures is by limiting the amount of gas exchange that occurs when diving. The sea lion allows the alveoli to be compressed by the increasing water pressure thus forcing the surface air into cartilage lined airway just before the gas exchange surface.
However, this shunt reduces the amount of compressed gases from entering tissues therefore reducing the risk of decompression sickness.
This means that sea lions must mitigate oxygen use in order to extend their dives. Oxygen availability is prolonged by the physiological control of heart rate in the sea lions. By reducing heart rate to well below surface rates, oxygen is saved by reducing gas exchange as well as reducing the energy required for a high heart rate. Digestion rate in these sea lions increases back to normal rates immediately upon resurfacing.
After a sea lion returns from a long dive, CO 2 is not expired as fast as oxygen is replenished in the blood, due to the unloading complications with CO 2. However, having more than normal levels of CO 2 in the blood does not seem to adversely affect dive behavior. Behavioural and environmental correlates of Philophthalmus zalophi , a foot parasite.
And the infection has impacted the survival of juvenile Galapagos sea lions Zalophus wollebaeki. The number of infectious stages of different parasites species has a strong correlation with temperature change, therefore it is essential to consider the correlation between the increasing number of parasitic infections and climate changes. To test this proposed theory researchers used Galapagos sea lions because they are endemic to the Galapagos islands. Parasites surfaced in large numbers when the sea temperature was at its highest.
Furthermore, data was collected by capturing sea lions in order to measure and determine their growth rates. Their growth rates were noted along with the citings of parasites which were found under the eyelid.
The shocking results were that sea lions are affected the parasites from the early ages of 3 weeks old up until the age of 4 to 8 months. From the data collected, 21 of the 91 survived; with a total of 70 deaths in just a span of two years. The death rates of the pups is surpassing the fertility rate by far.
Since most pups are unable to reach the age of reproduction, the population is not growing fast enough to keep the species out of endangerment. The pups who do survive must pass their strong genes down to make sure their young survive and the generation that follows. Other parasites, like Anisakis and heartworm can also infect sea lions. Along with Galapagos islands, sea lions Zalophus wollebaeki being affected are the Australian sea lions Neophoca cinerea.
The pups in Australia were being affected by hookworms, but they were also coming out in large numbers with warmer temperatures. The difference is that in New Zealand researchers took the necessary steps and began treatment. They found no traces of this infection afterwards. Overall parasites and hookworms are killing off enough pups to place them in endangerment.
Parasites affect sea pups in various areas of the world. Reproductive success reduces immensely, survival methods, changes in health and growth have also been affected. Similarly, climate change has resulted in increased toxic algae blooms in the oceans. These toxins are ingested by sardines and other fish which are then eaten by the sea lions, causing neurological damage and diseases such as epilepsy.
Gene expressions are being used more often to detect the physiological responses to nutrition, as well as other stressors. In a study done with four Steller sea lions Eumetopias jubatus , three of the four sea lions underwent a day trial which consisted of unrestricted food intake, acute nutritional stress, and chronic nutritional stress. Results showed that individuals under nutritional stress down-regulated some cellular processes within their immune response and oxidative stress.
Nutritional stress was considered the most proximate cause of population decline in this species. Geographic variation for sea lions have been determined by the observations of skulls of several Otariidae species; a general change in size corresponds with a change in latitude and primary productivity. Skulls of Australian sea lions from Western Australia were generally smaller in length whereas the largest skulls are from cool temperate localities.
Otariidae are in the process of species divergence, much of which may be driven by local factors, particularly latitude and resources. In a cool climate and cold waters there should be a selective advantage in the relative reduction of body surface area resulting from increased size, since the metabolic rate is related more closely to body surface area than to body weight.
Sea lions, with three groups of pinnipeds, have multiple breeding methods and habits over their families but they remain relatively universal. Otariids, or eared sea lions, raise their young, mate, and rest in more earthly land or ice habitats. Their abundance and haul-out behavior have a direct effect on their on land breeding activity. Their seasonal abundance trend correlates with their breeding period between the austral summer of January to March.
Their rookeries populate with newborn pups as well as male and female otariids that remain to defend their territories. At the end of the breeding period males disseminate for food and rest while females remain for nurturing. Other points in the year consist of a mix of ages and genders in the rookeries with haul-out patterns varying monthly.
Steller sea lions, living an average of 15 to 20 years, begin their breeding season when adult males establish territories along the rookeries in early May. Male sea lions reach sexual maturity from ages 5 to 7 and don't become territorial until around 9 to 13 years of age. The females arrive in late May bringing in an increase of territorial defense through fighting and boundary displays. After a week births consist most usually of one pup with a perinatal period of 3 to 13 days.
Steller sea lions have exhibited multiple competitive strategies for reproductive success. Sea lion mating is often polygamous as males usually mate with different females to increase fitness and success, leaving some males to not find a mate at all. Polygamous males rarely provide parental care towards the pup.
Strategies used to monopolize females include the resource-defense polygyny, or occupying important female resources. This involves occupying and defending a territory with resources or features attractive to females during sexually receptive periods. Some of these factors may include pupping habitat and access to water. Other techniques include potentially limiting access of other males to females. Otaria flavescens South American sea lion lives along the Chilean coast with a population estimate of , According to the most recent surveys in northern and southern Chile the sealing period of the middle twentieth century that left a significant decline in sea lion population is recovering.
The recovery is associated with less hunting, otariids rapid population growth, legislation on nature reserves, and new food resources. Haul-out patterns change the abundance of sea lions at particular times of the day, month, and year. Patterns in migration relate to temperature, solar radiation, and prey and water resources.
Studies of South American sea lions and other otariids document maximum population on land during early afternoon, potentially due to haul-out during high air temperatures. Adult and subadult males do not show clear annual patterns, maximum abundance being found from October to January.
Females and their pups hauled-out during austral winter months of June to September. South American sea lions have been greatly impacted by human exploitation. Sea lions rely on fish, like pollock, as a food source and have to compete with fishermen for it.
Sea lion attacks on humans are rare, but when humans come within approximately 2. The sea lion appeared to be preparing for a second attack when the girl was rescued. An Australian marine biologist suggested that the sea lion may have viewed the girl "like a rag doll toy" to be played with.
The attack left the man with a punctured bone. The child was sitting on a pier side in British Columbia while tourists were illegally feeding the sea lions when the incident took place. Sea lions have also been a focus of tourism in Australia and New Zealand. This tourist site receives over , visitors, many of whom are recreational boaters and tourists, who can watch the male sea lions haul out on to the shore.