Sea Lion

Sea lions are eared seals that are classified into five species and are distinguishable from fur seals in the same pinniped family, Otariidae, by their absence of underfur coated in long guard hairs, as well as their bigger size and less pointed snout. Seal lions, like other otariids, have a pinna on their head (the external part of the ear). Sea lions have traditionally been classified as a separate subfamily, however new research has found that this taxonomic split from fur seals is unnecessary. Seven species are currently recognised, one of which is extinct (the Japanese sea lion), and are classified under the five genera Eumetopias, Otaria, Neophoca, Phocarctos, and Zalophus.

With the notable exception of the Atlantic Ocean, sea lions' range stretches from the subarctic to tropical regions of the global ocean in both the northern and southern hemispheres. They are typically found in shallow waters along the coasts of both countries, where there are many food supplies. The training of sea lions to perform various practical underwater tasks, such as locating and retrieving objects of interest and detecting and attaching a clamp and retrieval line to persons approaching a military ship underwater, is one of the more remarkable examples of a harmonious relationship between humans and marine animals.

What is a Sea Lion?

Sea lions are a type of "eared seal," which are marine mammals that belong to the pinniped family Otariidae and are distinguished by the presence of a pinna (the external part of the ear), the ability to invert their hind-flippers under the body (assisting land movement), proportionally long and relatively muscular fore-flippers, and a swimming motion in which they propel themselves through the water using their long front flippers. There are 16 species of otariids left in the world, divided into seven genera and referred to as either fur seals or sea lions.

Until recently, all sea lions were classified as members of the Otariinae subfamily of Pinnipedia, while fur seals were classified as members of the Arctocephalinae subfamily. This was based on the greatest distinguishing characteristic of fur seals, notably their dense underfur intermixed with "guard" hairs, which are absent in sea lions. Fur seals have a "grizzled appearance" due to their long-haired underfur. Recent genetic data, on the other hand, reveals that the Northern fur seal genus Callorhinus is more closely linked to some sea lion species than to the fur seal genus Arctocephalus.

Despite this, all sea lions have some characteristics, such as coarse, short fur, bigger weight, larger prey, less pointed snouts, shorter fore-flippers, shorter and closer foraging trips, and so on. Their pelage is similarly lighter, with less noticeable vibrissae (whiskers). The distinction between sea lions and fur seals is nevertheless relevant for these reasons, despite the fact that it is not a true taxonomic rank. Fur seals belong to the Otariidae family, with the genera Callorhinus (one surviving species) and Arctocephalus (eight extant species). Sea lions belong to the following five genera: Eumetopias (one extant species), Otaria (one extant species), Neophoca (one extant species), Phocarctos (one extant species), and Zalophus (one extant species) (two extant and one recently extinct species).

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Sea Lion Scientific Classification

• Kingdom: Animalia

• Phylum: Chordata

• Class: Mammalia

• Order: Carnivora

• Clade: Pinnipedia

• Family: Otariidae

• Subfamily: Otariinae

SeaLion Physical Description

Sea lions, like other otariids, can move on all fours by turning their rear limbs forward.

Male sea lions are larger than female sea lions, and male sea lions are larger than female sea lions. Male sea lions range in length from 2 to 3 metres (6.5 to 11 feet) and weigh between 200 and 1,000 kilogrammes (440 to 2,200 pounds), while females are between 1.3 and 2.7 metres (4 to 9 feet) long and weigh between 50 and 270 kilogrammes (110 to 600 pounds).

The Steller sea lion (Eumetopias jubatus), sometimes known as the northern sea lion, is the largest of the eared seals (Otariidae); only the walrus and two elephant seals are larger pinnipeds. Males average 2.8 to 3.3 metres in length and weigh 600 to 1100 kilos (1,300 to 2,500 pounds). Females are only slightly smaller than males, but they have thinner chests, necks, and overall forebody structure; they stand 2.5 metres (8 feet) tall and weigh 300 kilogrammes on average (660 pounds).

Female California sea lions (Zalophus californianus) grow to be 90 kilogrammes (200 lb) and 2 metres (6.5 feet) long, while males grow to be 2.4 metres and 300 kilogrammes. Galápagos sea lions (Zalophus wollebaeki) grow to be 1.5 to 2.5 metres long and weigh 50 to 400 kilogrammes.

Male and female sea lions (bulls and cows) converge on land to give birth to pups. After that, the females go into oestrous and procreate on land once more. This occurs on an annual basis in most cases. The Australian sea lion's breeding cycle, on the other hand, is unique among pinnipeds. It runs for 18 months and is not coordinated between colonies.

Fish, molluscs (squid, clams), and crustaceans (crabs) are eaten by sea lions, and steller sea lions devour other seals. Food is usually swallowed whole, such as by throwing the fish until it can be positioned to be swallowed headfirst while utilising its firm back teeth to crush food with a hard shell. A sea lion's sensitive, long whiskers (vibrissa), which are linked to the upper lip, can aid in the detection of food in the dark.

SeaLion Diving Adaptation

The physiology of sea lions is made up of many different components, and these processes influence many elements of their behaviour. Thermoregulation, osmoregulation, reproduction, metabolic rate, and many other characteristics of sea lion ecology, including their capacity to dive to tremendous depths, are all dictated by physiology. The bodies of sea lions regulate heart rhythm, gas exchange, digestive rate, and blood flow, allowing them to dive for lengthy periods of time while avoiding the negative consequences of high pressure at depth.

Deep dives' high pressures cause gases like nitrogen to build up in tissues, which are subsequently released upon surfacing, potentially resulting in death. Limiting the quantity of gas exchange that occurs when diving is one of the ways sea lions manage the severe pressures. Reduced digesting rate is another method sea lions reduce the oxygen collected at the surface during dives. Digestive necessitates metabolic activity, which consumes energy and oxygen; nevertheless, sea lions can slow down their digestion rate by at least 54%.

Sea Lion Parasites and Diseases

Philophthalmus zalophi, a foot parasite, has behavioural and environmental correlations. The illness has also had an impact on the survival of young Galapagos sea lions (Zalophus wollebaeki).  This illness results in diseases linked to global warming. The researchers have found that sea lions are infected with parasites from the time they are 3 weeks old until they are 4 to 8 months old.

The parasites present in the eye fluke can cause severe eye injury. According to the information gathered, 21 of the 91 people survived, with a total of 70 deaths in just two years. The parasites are affecting the puppies at such an early age, preventing them from reaching reproductive age. The mortality rate of the pups significantly outnumbers the fertility rate. Because most pups do not reach reproductive age, the population does not develop quickly enough to keep the species from becoming endangered. Those pups that do make it must pass on their powerful genes to ensure the survival of their offspring and subsequent generations. Other parasites that can infect sea lions are Anisakis and heartworm.

The Australian sea lions (Zalophus wollebaeki) are also affected, in addition to the Galapagos Islands (Neophoca cinerea). Hookworms were affecting the pups in Australia, but they were also emerging in enormous numbers as the weather warmed. Hookworms also afflicted sea pups in New Zealand (Phocarctos hookeri) at an early age (Uncinaria). The difference is that researchers in New Zealand followed the necessary steps and started treatment. On the pups who received the medication, it appeared to be effective. After that, they detected no signs of the virus. The percentage of puppies who do have it, however, is still quite large, at around 75%. Puppies who were treated grew at a substantially faster rate than those who were not. Overall, parasites and hookworms are causing enough pups to perish, putting them in danger. Sea pups in different parts of the world are affected by parasites. Reproductive success is greatly reduced, as are survival tactics, changes in health, and growth.

In the oceans, climate change has resulted in a rise in hazardous algae blooms. Sardines and other fish take these toxins, which are then eaten by sea lions, causing neurological damage and disorders like epilepsy.

Geographic Variations in Sea Lions

The size of numerous Otariidae species' skulls has been used to assess geographic variation in sea lions; a general difference in size corresponds to a change in latitude and primary productivity. The smallest Australian sea lion skulls were found in Western Australia, whereas the largest skulls were found in cold temperate locations. The Otariidae family is undergoing species divergence, which may be influenced by local conditions such as latitude and resources. Populations of a specific species are typically smaller in the tropics, grow in size as latitude increases, and peak in subpolar regions. Because the metabolic rate is more directly related to body surface area than to body weight, there should be a selective advantage in the relative reduction of body surface area resulting from the increased size in a cool climate and cold waters.

Breeding Methods and Habits of Sea Lions

Sea lions, which are classified into three species of pinnipeds, have a variety of breeding procedures and habits that they use across their families, although they are largely universal. Eared sea lions, also known as otariids, raise their young, mate, and rest on more terrestrial land or ice habitats. Their on-land breeding activity is directly influenced by their abundance and haul-out behaviour. Their seasonal abundance pattern corresponds to their breeding season, which runs from January to March in the southern summer. Newborn puppies, as well as male and female otariids, occupy their rookeries to defend their territory. Males disperse for food and rest at the end of the breeding season, while females remain to care for their young.

Other times of the year, the rookeries have a mix of ages and genders, with monthly haul-out patterns.

Adult males establish territories along the rookeries in early May, beginning the breeding season for Steller sea lions, which live an average of 15 to 20 years. Male sea lions achieve sexual maturity between the ages of 5 and 7 but do not become territorial until they are between the ages of 9 and 13. Late in May, the females arrive, bringing with them an increase in territorial defence via fighting and border displays. After a week, most deliveries consist of one pup with a perinatal period of three to thirteen days.

For reproductive success, Steller sea lions have used a variety of competing techniques. Male sea lions frequently mate with multiple females in order to maximise fitness and success, leaving some guys without a mate at all. Polygamous males are less likely to provide parental care to their offspring. The resource-defence polygyny, or occupying vital female resources, is one strategy employed to monopolise females. During sexually receptive seasons, this entails occupying and defending an area with resources or traits attractive to females. Pupping habitat and access to water are two of these characteristics. Other methods include maybe restricting access of other males to females.

Sea Lion Population

With a population of 165,000, Otaria flavescens (South American sea lion) thrives along the Chilean coast. According to current surveys in northern and southern Chile, the mid-twentieth-century sealing phase, which resulted in a major drop in sea lion population, is now recovering. Less hunting, rapid otariid population growth, regulations on nature reserves, and new food resources are all contributing to the rebound. The amount of sea lions varies according to haul-out patterns at different times of the day, month, and year. Temperature, solar radiation, prey, and water availability all influence migration patterns. According to studies of South American sea lions and other otariids, the peak population on land occurs in the early afternoon, possibly due to haul-out during hot weather. Males, both adult and subadult, do not have distinct annual trends, with the highest abundance being from October to January. During the austral winter months of June to September, females and their pups hauled out.

Information About Various Sea Lion Breeds

Interactions With Humans

Sea lions may be trained in some species and are a popular attraction at zoos and aquariums. A sea lion is usually always the archetypal circus seal performing actions such as throwing and catching balls on its nose and applauding.

The Marine Mammal Program of the United States Navy has trained sea lions for military uses. They've been used in the Persian Gulf to detect and clamp swimmers or divers approaching ships with a rope attached. They can locate and attach recovery lines to things such as mines because of their near-infrared vision and outstanding directional underwater hearing.