The southern sleeper shark, or Whitley's sleeper shark (''Somniosus antarcticus''), is a deepwater

benthopelagic The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of ...

sleeper shark The Somniosidae are a family of sharks in the order Squaliformes, commonly known as sleeper sharks. The common name "''sleeper shark''" comes from their slow swimming, low activity level, and perceived non-aggressive nature. Distribution and hab ...

of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Somniosidae The Somniosidae are a family of sharks in the order Squaliformes, commonly known as sleeper sharks. The common name "''sleeper shark''" comes from their slow swimming, low activity level, and perceived non-aggressive nature. Distribution and hab ...

found in the southern and

subantarctic The sub-Antarctic zone is a physiographic region in the Southern Hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46th parallel south, 46° and 60th parallel south, 60° south of t ...

extremes of the

Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...

, Indian and

Pacific Oceans The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

, and some northern reaches of the

Antarctic The Antarctic (, ; commonly ) is the polar regions of Earth, polar region of Earth that surrounds the South Pole, lying within the Antarctic Circle. It is antipodes, diametrically opposite of the Arctic region around the North Pole. The Antar ...

oceans. It has been recorded near the southernmost areas of South America (such as

Tierra del Fuego Tierra del Fuego (, ; Spanish for "Land of Fire", rarely also Fireland in English) is an archipelago off the southernmost tip of the South America, South American mainland, across the Strait of Magellan. The archipelago consists of the main is ...

and the

Strait of Magellan The Strait of Magellan (), also called the Straits of Magellan, is a navigable sea route in southern Chile separating mainland South America to the north and the Tierra del Fuego archipelago to the south. Considered the most important natura ...

), near

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

, southern Australia,

Tasmania Tasmania (; palawa kani: ''Lutruwita'') is an island States and territories of Australia, state of Australia. It is located to the south of the Mainland Australia, Australian mainland, and is separated from it by the Bass Strait. The sta ...

and New Zealand, as well as more remote locations in the south-central Indian Ocean.

Taxonomy

It was formerly sometimes viewed as

conspecific Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species. Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organism ...

with either the

Greenland shark The Greenland shark (''Somniosus microcephalus''), also known as the gurry shark or grey shark, is a large shark of the family Somniosidae ("sleeper sharks"), closely related to the Pacific and southern sleeper sharks. Inhabiting the North Atl ...

(''Somniosus microcephalus''), or the Pacific sleeper shark (''Somniosus pacificus'').

Habitat

A deepwater species, the southern sleeper shark is known to frequent waters around 400m (1312 feet) to as deep as 1100m (3608 feet).

Description

The southern sleeper shark's body length measures up to . This species differs from the Greenland shark (''S. microcephalus'') with the presence of additional rows of teeth in its lower jaw, a shorter interdorsal region, a more posterior first

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

, and fewer precaudal vertebrae. Compared to both the Greenland and the Pacific sleeper shark (''S. pacificus''), the southern sleeper has lower dorsal fins, which the other two do not.

Diet

The southern sleeper shark feeds primarily on

cephalopod A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...

s, especially

squid A squid (: squid) is a mollusc with an elongated soft body, large eyes, eight cephalopod limb, arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida (though many other molluscs within the broader Neocoleoidea are also ...

— including the

giant In folklore, giants (from Ancient Greek: ''wiktionary:gigas, gigas'', cognate wiktionary:giga-, giga-) are beings of humanoid appearance, but are at times prodigious in size and strength or bear an otherwise notable appearance. The word ''gia ...

and

colossal squid The colossal squid (''Mesonychoteuthis hamiltoni'') is a species of very large squid belonging to the family Cranchiidae, that of the cockatoo squids or glass squids. It is sometimes called the Antarctic cranch squid or giant squid (not to b ...

s — and numerous

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

es. Documented stomach contents of individual sleeper sharks have also, albeit infrequently, contained the remains of

marine mammal Marine mammals are mammals that rely on marine ecosystems for their existence. They include animals such as cetaceans, pinnipeds, sirenians, sea otters and polar bears. They are an informal group, unified only by their reliance on marine enviro ...

s or

seabird Seabirds (also known as marine birds) are birds that are adaptation, adapted to life within the marine ecosystem, marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent ...

s, possibly as a result of scavenging on sunken carcasses or

whale fall A whale fall occurs when the Carrion, carcass of a whale has fallen onto the ocean floor, typically at a depth greater than , putting them in the Bathyal zone, bathyal or abyssal zones. On the sea floor, these carcasses can create complex local ...

s. Based on its generally sluggish nature and the comparative speed of its prey, it is thought to be an

ambush predator Ambush predators or sit-and-wait predators are carnivorous animals that capture their prey via stealth, luring or by (typically instinctive) strategies utilizing an element of surprise. Unlike pursuit predators, who chase to capture prey u ...

. A long female, caught off the coast of

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

, had a whole

southern right whale dolphin The southern right whale dolphin (''Lissodelphis peronii'') is a small and slender species of cetacean, found in cool waters of the Southern Hemisphere. It is one of two species of right whale dolphin (genus ''Lissodelphis''). This genus is char ...

in its stomach. The dogfish is sometimes taken as accidental

bycatch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...

in the

orange roughy The orange roughy (''Hoplostethus atlanticus''), also known as the red roughy, slimehead and deep sea perch, is a relatively large deep-sea fish belonging to the slimehead family (Trachichthyidae). It is bathypelagic, found in cold (), deep () ...

and Patagonian toothfish fisheries; whether or not this poses a threat to the species is currently unknown.

Conservation status

In June 2018 the New Zealand Department of Conservation classified the southern sleeper shark as "Not Threatened" with the qualifiers "Data Poor" and "Uncertain whether Secure Overseas" under the

New Zealand Threat Classification System The New Zealand Threat Classification System is used by the Department of Conservation to assess conservation priorities of species in New Zealand. The system was developed because the IUCN Red List, a similar conservation status system, had s ...

. The IUCN also does not regard it as threatened, noting a widespread distribution and no indication of a declining population, but believes it is not naturally abundant and that much more data and understanding of its population, interactions and biology is needed.

References

{{DEFAULTSORT:Southern sleeper shark Somniosus Fish described in 1939 Fish of the Atlantic Ocean Fish of the Indian Ocean Fish of the Pacific Ocean Taxonomy articles created by Polbot