Zalophus

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Zalophus
Lion de mer Amneville 01.jpg
Californian sea lion
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Clade: Pinnipedia
Family: Otariidae
Subfamily: Otariinae
Genus: Zalophus
Gill, 1866
Type species
Otaria gilliespii (= Otaria californiana )
Lesson, 1828
Zalophus distribution.png
 Z. californiana breeding range

 Z. californiana total range

 Z. wollebaeki range

Zalophus is a genus of the family Otariidae (sea lions and fur seals) of the order Carnivora.

Contents

Description

The seals of the genus Zalophus present a striking sexual dimorphism, since the adult males have a pronounced sagittal crest, and weigh, in the Californian species, between 300 and 380 kg with 240 cm long, and the females 80 to 120 kg with between 180 and 200 cm. As with all ear seals, the males are significantly larger and heavier than the females. The males are dark brown in color, the females are lighter. In contrast to the other ear seals, the males do not have a clearly defined mane. In the Galapagos species the males weigh about 250 kg with a length of 250 to 270 cm, while the females weigh from 60 to 100 kg with a length of between 150 and 170 cm.

They have a streamlined body, with a layer of fat under the skin, to provide warmth and buoyancy. The coat is brown. They have large eyes that help compensate for low light levels in the underwater environment, while their whiskers increase their sense of touch. The nostrils close automatically once they touch the water. Their long front fins rotate outward for better movement on land, and propel them forward in the water, where they stay as long as possible.

Systematics

For a long time, specialists debated whether the 3 taxa that make up this genus would be three full, monotypic species, or instead integrate a single species with three subspecies, in the latter case, by priority, it would be the Zalophus californianus species.

As early as 1953, the zoologist Erling Sivertsen created a new indicative classification, after he investigated and cataloged again, in the Oslo Museum, skulls and archaeological remains, collected by the Norwegian expedition ship MK Norvegia, 5 between 1928 and 1929 A comprehensive study of molecular genetics by the Institute of Genetics at the University of Cologne, the Max Planck Institute for Evolutionary Biology in Plön, and the Department of Behavioral Sciences at the University of Bielefeld, 6 concluded 50 years after the mitochondria and cell nuclei SNPs support a separation into three species.

According to their "molecular clocks", the Galapagos sea lion branch departed from the California sea lion branch 2.3 (± 0.5) million years ago. so that it must be based on the idea that it is an independent species, especially when in The study of the genetics of the population of the Galapagos taxon it does not present the classic "bottleneck" effect, thus reinforcing its condition. full species.

Traditionally, the three populations were listed as subspecies of a common species, but this was controversial. Wilson & Reeder classified the three populations as separate species. A molecular genetic study by Wolf et al. (2007) came to the same conclusion. As a result, the mitochondrial and cell nucleus SNPs justify separation into several species. According to the molecular clock, the Californian and Galápagos sea lions separated around 2.3 (± 0.5) million years ago.

Species

It includes these species, [1] of which one became recently extinct:

ImageNameDistribution
California sea lion in La Jolla (70568).jpg Z. californianus: California sea lion [2] western coast and islands of North America, from southeast Alaska to central Mexico.
Excursion to a lagoon on the N side of Isla Santa Fe - Galapagos Sea Lion (Zalophus californianus) (16492679320).jpg Z. wollebaeki: Galápagos sea lion [3] Ecuadorian coast north to Isla Gorgona in Colombia.
Zalophus japonicus.JPG Z. japonicus: Japanese sea lion [4] Japan and Korea; vagrant to southern Kamchatka Peninsula and Sakhalin Island in Russia

Ecology

These seals go to rest on the coasts. When looking for food, they dive up to 40 meters deep and prey on fish and octopus. During the breeding season, the males establish strictly guarded territories on the coasts and try to gain a harem from several females.

They feed on fish and mollusks. They are very sociable and are found in large groups, on cliffs, coasts, and even on human constructions, such as piers and navigation bowls.

Reproduction

Unlike fur seals ( Arctocephalus ) which live in well-structured social groups, the species of the genus Zalophus form variable groups lacking in organization, 8 although the males are also territorial and usually form harems of about fifteen females each. Males make loud sounds to mark territory. They usually mate between May and January depending on the species. Females give birth to only one young, which is born on land or water after a gestation that lasts between 342 and 365 days. They are the only mammals whose milk does not contain lactose. Females wean their young after 11 to 12 months, but some nurse their one-year-old pups alongside their newborns.

Related Research Articles

<span class="mw-page-title-main">Fur seal</span> Subfamily of mammals

Fur seals are any of nine species of pinnipeds belonging to the subfamily Arctocephalinae in the family Otariidae. They are much more closely related to sea lions than true seals, and share with them external ears (pinnae), relatively long and muscular foreflippers, and the ability to walk on all fours. They are marked by their dense underfur, which made them a long-time object of commercial hunting. Eight species belong to the genus Arctocephalus and are found primarily in the Southern Hemisphere, while a ninth species also sometimes called fur seal, the Northern fur seal, belongs to a different genus and inhabits the North Pacific. The fur seals in Arctocephalus are more closely related to sea lions than they are to the Northern fur seal, but all three groups are more closely related to each other than they are to true seals.

<span class="mw-page-title-main">Eared seal</span> Marine mammals in the family Otariidae

An eared seal, otariid, or otary is any member of the marine mammal family Otariidae, one of three groupings of pinnipeds. They comprise 15 extant species in seven genera and are commonly known either as sea lions or fur seals, distinct from true seals (phocids) and the walrus (odobenids). Otariids are adapted to a semiaquatic lifestyle, feeding and migrating in the water, but breeding and resting on land or ice. They reside in subpolar, temperate, and equatorial waters throughout the Pacific and Southern Oceans, the southern Indian, and Atlantic Oceans. They are conspicuously absent in the north Atlantic.

<span class="mw-page-title-main">California sea lion</span> Species of carnivore

The California sea lion is a coastal eared seal native to western North America. It is one of six species of sea lions. Its natural habitat ranges from southeast Alaska to central Mexico, including the Gulf of California. California sea lions are sexually dimorphic; males are larger than females, and have a thicker neck, and a protruding sagittal crest. They mainly haul-out on sandy or rocky beaches, but they also frequent manmade environments such as marinas and wharves. California sea lions feed on a number of species of fish and squid, and are preyed on by orcas and great white sharks.

<span class="mw-page-title-main">Sea lion</span> Subfamily of aquatic mammals

Sea lions are pinnipeds characterized by external ear flaps, long foreflippers, the ability to walk on all fours, short and thick hair, and a big chest and belly. Together with the fur seals, they make up the family Otariidae, eared seals. The sea lions have six extant and one extinct species 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. They have an average lifespan of 20–30 years. A male California sea lion weighs on average about 300 kg (660 lb) and is about 2.4 m (8 ft) long, while the female sea lion weighs 100 kg (220 lb) and is 1.8 m (6 ft) long. The largest sea lions are Steller's sea lions, which can weigh 1,000 kg (2,200 lb) and grow to a length of 3.0 m (10 ft). Sea lions consume large quantities of food at a time and are known to eat about 5–8% of their body weight at a single feeding. Sea lions can move around 16 knots in water and at their fastest they can reach a speed of about 30 knots. Three species, the Australian sea lion, the Galápagos sea lion and the New Zealand sea lion, are listed as endangered.

<span class="mw-page-title-main">Pinniped</span> Infraorder of mammals

Pinnipeds, commonly known as seals, are a widely distributed and diverse clade of carnivorous, fin-footed, semi-aquatic, and mostly marine mammals. They comprise the extant families Odobenidae, Otariidae, and Phocidae, with 34 extant species and more than 50 extinct species described from fossils. While seals were historically thought to have descended from two ancestral lines, molecular evidence supports them as a monophyletic lineage. Pinnipeds belong to the clade Caniformia of the order Carnivora; their closest living relatives are musteloids, having diverged about 50 million years ago.

<span class="mw-page-title-main">Japanese sea lion</span> Extinct species of sea lion from East Asia

The Japanese sea lion was an aquatic mammal that became extinct in the 1970s. It was considered to be a subspecies of the related California sea lion until 2003. They inhabited the western North Pacific and its marginal seas including the Sea of Okhotsk and the Sea of Japan, especially around the coastal areas of the Japanese Archipelago and the Korean Peninsula. They generally bred on sandy beaches which were open and flat, but sometimes in rocky areas. They were hunted commercially in the 1900s, leading to their extinction.

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The brown hyena, also called strandwolf, is a species of hyena found in Namibia, Botswana, western and southern Zimbabwe, southern Mozambique and South Africa. It is the only extant species in the genus Parahyaena. It is currently the rarest species of hyena. The largest remaining brown hyena population is located in the southern Kalahari Desert and coastal areas in Southwest Africa. The global population of brown hyena is estimated by IUCN at a number between 4,000 and 10,000 and its conservation status is marked as near threatened in the IUCN Red List.

<span class="mw-page-title-main">Northern fur seal</span> Only fur seal in the northern hemisphere

The northern fur seal is an eared seal found along the north Pacific Ocean, the Bering Sea, and the Sea of Okhotsk. It is the largest member of the fur seal subfamily (Arctocephalinae) and the only living species in the genus Callorhinus. A single fossil species, Callorhinus gilmorei, is known from the Pliocene of Japan and western North America.

<span class="mw-page-title-main">Galápagos fur seal</span> Species of carnivore

The Galápagos fur seal is one of eight seals in the genus Arctocephalus and one of nine seals in the subfamily Arctocephalinae. It is the smallest of all of the eared seals. They are endemic to the Galápagos Islands in the eastern Pacific. The total estimated population as of 1970 was said to be about 30,000, although the population has been said to be on the decline since the 1980s due to environmental factors such as pollution, disease, invasive species, and their limited territory. Due to the population having been historically vulnerable to hunting, the Galápagos fur seal has been protected by the Ecuadorian government since 1934

<span class="mw-page-title-main">South American sea lion</span> Species of carnivore

The South American sea lion, also called the southern sea lion and the Patagonian sea lion, is a sea lion found on the western and southeastern coasts of South America. It is the only member of the genus Otaria. The species is highly sexually dimorphic. Males have a large head and prominent mane. They mainly feed on fish and cephalopods and haul out on sand, gravel, rocky, or pebble beaches. In most populations, breeding males are both territorial and harem holding; they establish territories first and then try to herd females into them. The overall population of the species is considered stable, estimated at 265,000 animals.

<span class="mw-page-title-main">Leaf muntjac</span> Species of deer

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<span class="mw-page-title-main">Galapagos hawk</span> Species of bird

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<span class="mw-page-title-main">Galapagos shark</span> Species of shark

The Galapagos shark is a species of requiem shark, in the family Carcharhinidae, found worldwide. It favors clear reef environments around oceanic islands, where it is often the most abundant shark species. A large species that often reaches 3.0 m (9.8 ft), the Galapagos reef shark has a typical fusiform "reef shark" shape and is very difficult to distinguish from the dusky shark and the grey reef shark. An identifying character of this species is its tall first dorsal fin, which has a slightly rounded tip and originates over the rear tips of the pectoral fins.

<span class="mw-page-title-main">Galápagos sea lion</span> Species of carnivore

The Galápagos sea lion is a species of sea lion that lives and breeds on the Galápagos Islands and, in smaller numbers, on Isla de la Plata (Ecuador). Being fairly social, they are often spotted sun-bathing on sandy shores or rock groups, or gliding through the surf. They are the smallest sea lion species.

<span class="mw-page-title-main">Baboon</span> Genus of mammals

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<i>Oxyjulis</i> Species of fish

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References

  1. Don E. Wilson & DeeAnn M. Reeder (editors). 2005. Mammal Species of the World. A Taxonomic and Geographic Reference (3rd ed), Johns Hopkins University Press, 2,142 pp. Online
  2. Seal Specialist Group 1996. Zalophus californianus. In: IUCN 2007. 2007 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 07 March 2008.
  3. Seal Specialist Group 1996. Zalophus wollebaeki. In: IUCN 2007. 2007 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 07 March 2008.
  4. Seal Specialist Group 1996. Zalophus japonicus. In: IUCN 2007. 2007 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 07 March 2008.