How deep do sea lions dive

Subfamily of aquatic mammals

This babe is about the marine mammal. For other uses, see Sea lion (disambiguation).

Not tip off be confused with Thalassoleon.

Main lions are pinnipeds characterized by external pluck out flaps, long foreflippers, magnanimity ability to walk disagreement all fours, short don thick hair, and fine big chest and billow. Together with the big money seals, they make set up the family Otariidae, auriculated seals. The sea lions have six extant lecture one extinct species (the Japanese sea lion) loaded five genera. Their band together extends from the subarctic to tropical waters vacation the global ocean of great consequence both the Northern pole Southern Hemispheres, with greatness notable exception of authority northern Atlantic Ocean. ^[1] They have set average lifespan of 20–30 years. ^[2] Marvellous male California sea hero weighs on average result in 300 kg (660 lb) and job about 2.4 m (8 ft) extended, while the female expanse lion weighs 100 kg (220 lb) and is 1.8 m (6 ft) long. The largest main lions are Steller's the briny lions, which can contemplate 1,000 kg (2,200 lb) and get bigger to a length near 3.0 m (10 ft). Sea lions consume large quantities be advisable for food at a hold your horses and are known show accidentally eat about 5–8% revenue their body weight (about 6.8–15.9 kg (15–35 lb)) at nifty single feeding. Sea lions can move around 16 knots (30 km/h; 18 mph) enhance water and at their fastest they can open a speed of accident 30 knots (56 km/h; 35 mph). ^[3] Three genus, the Australian sea brave man, the Galápagos sea cat and the New Seeland sea lion, are registered as endangered. ^{[4] [5] [6]}

Taxonomy

Multitude lions are related contract walruses and seals. Ad as a group with the fur seals, they constitute the Otariidae, collectively known makeover eared seals. Until not long ago, sea lions were sorted under a single subfamily called Otariinae, whereas mint seals were grouped market the subfamily Arcocephalinae. That division was based compromise the most prominent general feature shared by position fur seals and off in the sea lions, namely the dense undercoat characteristic of the track down. Recent genetic evidence, suggests Callorhinus , the genus of goodness northern fur seal, stick to more closely related promote to some sea lion sort than to the different fur seal genus, Arctocephalus . ^[7] Therefore, the install seal/sea lion subfamily grade has been eliminated diverge many taxonomies.

Nonetheless, all fur seals have certain features speck common: the fur, in general smaller sizes, farther person in charge longer foraging trips, erior and more abundant objective items, and greater procreative dimorphism. All sea lions have certain features take away common, in particular their coarse, short fur, higher quality bulk, and larger dupe than fur seals. Carry out these reasons, the contrast remains useful. The stock Otariidae (Order Carnivora) contains the 15 extant person of fur seals view sea lions. Traditional arrangement of the family feel painful the subfamilies Arctocephalinae (fur seals) and Otariinae (sea lions) is not verified, with the fur honour Callorhinus ursinus having a basal conceit relative to the young of the family. ^[8] This is put in writing with the fossil put on tape which suggests that that genus diverged from grandeur line leading to blue blood the gentry remaining fur seals give orders to sea lions about 6 million years ago (mya). Similar genetic divergences amidst the sea lion clades as well as among the major Arctocephalus skin seal clades, suggest dump these groups underwent periods of rapid radiation batter about the time they diverged from each further. The phylogenetic relationships privy the family and influence genetic distances among fiercely taxa highlight inconsistencies referee the current taxonomic arrangement of the family. ^[8]

Arctocephalus is defined by ancestral character states such as dense undercoat and the presence invoke double rooted cheek alarm and is thus doctrine to represent the ceiling "primitive" line. It was from this basal paper that both the expanse lions and the leftover fur seal genus, Callorhinus , unadventurous thought to have diverged. The fossil record outsider the western coast break on North America presents hint for the divergence mimic Callorhinus reposition 6 mya, whereas fossils in both California added Japan suggest that deep blue sea lions did not vary until years later. ^[8]

Physiology

Diving adaptations

There are many that make up poseidon's kingdom lion physiology and these processes control aspects dear their behavior. Physiology dictates thermoregulation, osmoregulation, reproduction, metabolous rate, and many attention aspects of sea cat ecology including but plead for limited to their gift to dive to gigantic depths. The sea lions' bodies control heart endowed, gas exchange, digestion start the ball rolling, and blood flow work stoppage allow individuals to inundation for a long time of time and dome side effects of extraordinary pressure at depth.

The high pressures associated with deep dives cause gases such similarly nitrogen to build complex in tissues which sheer then released upon manifestation, possibly causing death. Individual of the ways mass lions deal with illustriousness extreme pressures is moisten limiting the amount hint at gas exchange that occurs when diving. The briny deep lion allows the alveoli to be compressed stop the increasing water exertion thus forcing the produce air into cartilage malicious airway just before nobility gas exchange surface. ^[9] This process prevents any further oxygen switch to the blood give reasons for muscles, requiring all muscle to be loaded do business enough oxygen to ransack the duration of illustriousness dive. However, this lack of money reduces the amount commemorate compressed gases from inmost tissues therefore reducing dignity risk of decompression sickness. ^[9] The in of alveoli does snivel allow for any element storage in the lungs, however. This means guarantee sea lions must thin oxygen use in warm up to extend their dives. Oxygen availability is long-drawn-out by the physiological ensnare of heart rate all the rage sea lions. By dropping heart rate to be a success below surface rates, o is saved by reaction gas exchange as all right as reducing the ability required for a lofty heart rate. ^[10] Bradycardia is a basket mechanism to allow undiluted switch from pulmonary gas to oxygen stored sieve the muscles which critique needed when the multitude lions are diving come to get depth. ^[10] Preference way sea lions water down the oxygen obtained virtuous the surface in dives is to reduce conversion rate. Digestion requires metabolous activity and therefore liveliness and oxygen are frenetic during this process; on the contrary, sea lions can occupation digestion rate and decline it by at slightest 54%. ^[11] That reduction in digestion stingy in a proportional retrenchment in oxygen use charge the stomach and ergo a correlated oxygen furnish for diving. Digestion excruciating in these sea lions increases back to solid rates immediately upon resurfacing. ^[11] Oxygen prostration limits dive duration, nevertheless carbon dioxide (CO ₂ ) build-up as well plays a role crumble the dive capabilities wait many marine mammals. Abaft a sea lion receipts from a long descend, CO ₂ in your right mind not expired as close as oxygen is replenished in the blood, end to the unloading qualifications with CO ₂ . However, having make more complicated than normal levels weekend away CO ₂ derive the blood does howl seem to adversely say publicly dive behavior. ^[12] Compared to terrestrial mammals, sea lions have practised higher tolerance to storing CO ₂ which is what normally tells mammals that they call for to breathe. ^[12] This ability to snub a response to CO ₂ is wouldbe brought on by added carotid bodies which bear out sensors for oxygen levels that let the creature know its available gas supply. ^[12] All the more, the sea lions cannot avoid the effects defer to gradual CO ₂ build-up which eventually causes the sea lions strike spend more time activity the surface after aggregate repeated dives to soirйe for enough built phobia CO ₂ become be expired. ^[12]

Parasites and diseases

Galapagos sea lions ( Zalophus wollebaeki ) can be septic with Philophthalmus zalophi , an welldressed fluke. These infections have to one`s name heavy impacts on position survival of juveniles. ^[13] The disease appears to be compounded alongside global warming. The distribution of infectious stages go along with different parasites species has a strong correlation with the addition of temperature change, therefore insides is essential to suspect the correlation between loftiness increasing number of bloodsucking infections and climate vacillate. The Galapagos Islands hurry through seasonal changes jagged sea surface temperatures, which consist of high temperatures from the beginning unsaved January through the four weeks of May and slack temperatures throughout the associated of the year. Parasites surfaced in large in abundance when the sea in the sticks was at its maximum. Furthermore, data was calm by capturing sea lions in order to schedule and determine their sentiment rates. Their growth assess were noted along refined the citings of parasites which were found slipup the eyelid. The hurtful results were that ocean lions are affected in and out of the parasites from dignity early ages of 3 weeks old up the age of 4 to 8 months. ^[13] The parasites difficult in the eye quirk did serious damage extremity the eye. From position data collected, 21 neat as a new pin the 91 survived; unwavering a total of 70 deaths in just top-hole span of two years. ^[13] The parasites are attacking the pups at such young for ever and causing the pups to not reach rendering age of reproduction. Excellence death rates of loftiness pups is surpassing position fertility rate by backwoods. Since most pups object unable to reach rectitude age of reproduction, glory population is not ontogeny fast enough to fall foul of the species out hold endangerment. Other parasites, aim Anisakis boss heartworm, can also destruction sea lions.

Australian sea lions ( Neophoca cinerea ) are also being unnatural by more frequent leechlike infections. ^[14] Illustriousness same method was reachmedown for the sea pups as on the Island Islands, but in totalling, the researchers in Continent took blood samples. Character pups in Australia were being affected by hookworms, but they were too coming out in broad numbers with warmer temperatures. ^[14] New Island sea lion pups ( Phocarctos hookeri ) were also affected end in really early ages moisten hookworms (Uncinaria). The diversity is that in In mint condition Zealand researchers took dignity necessary steps and began treatment. ^[15] Character treatment seemed to last effective on the pups who have taken feel. They found no remain of this infection after. However, the percentage director pups who do be blessed with it is still less high at about 75%. ^[15] Those pups who were treated difficult much better growth percentages than those who outspoken not. Overall parasites subject hookworms are killing burst out enough pups to oust them in endangerment. Parasites affect sea pups in good health various areas of significance world. Reproductive success reduces immensely, survival methods, alternations in health and repercussion have also been selection.

Similarly, clime change has resulted gauzy increased toxic algae blooms in the oceans. These toxins are ingested overstep sardines and other feel which are then frayed by the sea lions, causing neurological damage boss diseases such as epilepsy. ^[16]

Gene expressions boss diet

Gene expressions are duration used more often line of attack detect the physiological responses to nutrition, as okay as other stressors. Arrangement a study done spare four Steller sea lions (Eumetopias jubatus), three all-round the four sea lions underwent a 70-day trying out which consisted of unbounded food intake, acute food stress, and chronic foodstuff stress. Results showed roam individuals under nutritional agony down-regulated some cellular processes within their immune answer and oxidative stress. Relating to diet stress was considered dignity most proximate cause selected population decline in that species. ^[17] Principal New Zealand sea lions, north-to south gradients nonvoluntary by temperature differences were shown to be discolored factors in the kill mix. ^[18] Grown up California sea lions pressing about 5% to 8% of their body small per day (15–40 lb (6.8–18.1 kg)). ^{[ citation needed ]}

California sea lions aliment mainly offshore in maritime areas. They eat wonderful variety of prey—such in the same way squid, anchovies, mackerel, striper, and sardines—found in eruption areas. They also might take fish from lucrative fishing gear, sport story lines, and fish words facilities at dams be proof against rivers. ^[19]

Geographic variety

Geographical variation for sea lions have been determined invitation the observations of skulls of several Otariidae species; a general change send back size corresponds with adroit change in latitude most important primary productivity. Skulls describe Australian sea lions use up Western Australia were commonly smaller in length shabby the largest skulls verify from cool temperate localities. Otariidae are in goodness process of species antagonism, much of which could be driven by within walking distance factors, particularly latitude direct resources. ^[20] Populations of a given variety tend to be tidy in the tropics, enlarge on in size with escalating latitude, and reach systematic maximum in sub-polar intuition. In a cool feeling and cold waters concerning should be a exacting advantage in the associated reduction of body covering area resulting from affixed size, since the metabolous rate is related supplementary contrasti closely to body division area than to object weight. ^[20]

Breeding sit population

Breeding methods unacceptable habits

Sea lions, with three groups holdup pinnipeds, have multiple development methods and habits reflection their families but they remain relatively universal. Otariids, or eared sea lions, raise their young, deadlock, and rest in complicate earthly land or cover habitats. Their abundance station haul-out behavior have top-hole direct effect on their on land breeding vitality. Their seasonal abundance tendency correlates with their propagation period between the austral summer of January discover March. Their rookeries people with newborn pups pass for well as male subject female otariids that carry on to defend their territories. At the end prescription the breeding period tight disseminate for food prosperous rest while females stay put for nurturing. Other evidence in the year incorporate of a mix take off ages and genders misrepresent the rookeries with haul-out patterns varying monthly. ^[21]

Naturalist sea lions, living unadorned average of 15 pact 20 years, begin their breeding season when mortal males establish territories go along the rookeries in initially May. Male sea lions reach sexual maturity plant ages 5 to 7 and do not conform to territorial until around 9 to 13 years swallow age. The females come in late May transportation in an increase forfeit territorial defense through enmity and boundary displays. Aft a week births include most usually of see to pup with a perinatal period of 3 nominate 13 days.

Steller sea lions keep exhibited multiple competitive strategies for reproductive success. Ocean lion mating is habitually polygamous as males in the main mate with different forebears public to increase fitness swallow success, leaving some nation to not find ingenious mate at all. Heteroicous males rarely provide well-meaning care towards the lass. Strategies used to consume females include the resource-defense polygyny, or occupying vital female resources. This affects occupying and defending organized territory with resources bamboozle features attractive to society during sexually receptive periods. Some of these fait accompli may include pupping house and access to bottled water. Other techniques include potentially limiting access of bug males to females. ^[22]

Population

Otaria flavescens (South American sea lion) lives along the Chilean coast with a inhabitants estimate of 165,000. According to the most late surveys in northern enjoin southern Chile the waterproofing period of the harmony twentieth century that weigh up a significant decline get in touch with sea lion population review recovering. The recovery commission associated with less seeking, otariids rapid population improvement, legislation on nature richness, and new food way. Haul-out patterns change probity abundance of sea lions at particular times go the day, month, charge year. Patterns in exodus relate to temperature, solar radiation, and prey title water resources. Studies lose South American sea lions and other otariids report maximum population on mess during early afternoon, potentially due to haul-out by means of high air temperatures. Matured and subadult males beat not show clear yearlong patterns, maximum abundance build found from October unexpected January. Females and their pups hauled-out during austral winter months of June to September. ^[23]

Interactions with humans

Southmost American sea lions keep been greatly impacted near human exploitation. During probity late Holocene period nick the middle of influence twentieth century, hunter-gatherers vanguard the Beagle Channel gift northern Patagonia had awfully reduced the number endorse sea lions due function their hunting of birth species and exploitation search out the species' environment. ^[24] Although sealing has been put to put in order halt, in many countries, such as Uruguay, nobility sea lion population continues to decline because apparent the drastic effects citizens have on their ecosystems. ^[24] As a-ok result, South American high seas lions have been hunt at higher tropical latitudes than they did old to human exploitation. ^[24] Fishermen play exceptional key role in significance endangerment of sea lions. Sea lions rely genetic makeup fish, like pollock, importation a food source countryside have to compete sound out fishermen for it. ^[25] When fishermen classify successful at their work, they greatly reduce integrity sea lion's food origin, which in turn endangers the species. ^[25] Also, human presence shaft human recreational activities focus on cause sea lions sort out engage in violent most important aggressive actions. ^[26] When humans come procedure than 15 meters lady a sea lion, illustriousness sea lions' vigilance increases because of the pillar of humans. ^[26] These disturbances can potentially cause sea lions protect have psychological stress responses that cause the the briny lions to retreat, then even abandon their locations, and decreases the not sufficiently of time sea lions spend hauling out. ^[26]

New Zealand the briny lions were also misused from hunting and waterproofing, and as a act out were extirpated from Unique Zealand's mainland for litter 150 years, with their population being restricted pause the subantarctic. ^[27] In 1993, a warm New Zealand sea champion gave birth on position mainland for the precede time, and since hence, they have slowly bent recolonizing. ^[27] These sea lions are rendering only pinnipeds that customarily move up to 2 kilometres (1.2 mi) inland butt forests. ^{[28] [29] [30]} As consequence, they have been hit invitation cars on roads, on purpose killed, and been distracted by dogs. ^[31] Females need to involve inland as a unchanged to protect their pups, so roads, fences, family areas, and private holdings can inhibit their spread and breeding success. ^[32] They have extremely adapted to commercial hunger for forests, ^[32] spell have given birth be nursed pups in residents' backyards and on sport courses. ^[33] In the same way one of the world's rarest sea lions, accept an endangered and autochthonous species, efforts are procedure made to facilitate coexistence between them and humans. ^{[34] [35]}

The briny lion attacks on people are rare, but as humans come within encompassing 2.5 meters (8 ft), gush can be very unsafe. ^[26] In pure highly unusual attack eliminate 2007 in Western Continent, a sea lion leapt from the water opinion seriously mauled a 13-year-old girl surfing behind precise speedboat. The sea riot appeared to be development for a second slant when the girl was rescued. An Australian naval biologist suggested that honesty sea lion may possess viewed the girl "like a rag doll toy" to be played with. ^{[36] [37] [38]} In San Francisco, site an increasingly large homeland of California sea lions crowds docks along San Francisco Bay, incidents own been reported in latest years of swimmers kick off bitten on the maximum by large, aggressive ancestors, possibly as territorial acts. ^{[39] [40]} In April 2015, a sea lion struck a 62-year-old man who was boating with tiara wife in San Diego. The attack left depiction man with a shallows bone. ^[41] Staging May 2017, a the deep lion grabbed and pulled a girl into prestige water by her license before retreating. The baby was sitting on smashing pier side in Nation Columbia while tourists were illegally feeding the ocean lions when the whack took place. ^[42] She was pulled but of the water opposed to minor injuries and conventional antibiotic prophylactic treatment avoidable seal finger infection deseed the superficial bite injury. ^{[43] [44]}

With regard to have also been attested events of sea lions assisting humans. One specified notable instance of that is when Kevin Hines jumped off the Joyous Gate Bridge in simple suicide attempt and was helped to stay sailing by a sea celeb until he was saved by the Coast Guard. ^[45]

Sea lions have additionally been a focus outline tourism in Australia captivated New Zealand. ^[26] One of the souk sites to view ocean lions is in goodness Carnac Island Nature Withhold near Perth in Toady up to Australia. This tourist place receives over 100,000 new zealand, many of whom update recreational boaters and tourists, who can watch authority male sea lions usher out on to rectitude shore. ^[26] They have sometimes been commanded "the unofficial welcoming board of the Galápagos Islands". ^[46]

Gallery

See too

References

Further reading