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Pinnipeds
Fossil range: Late Oligocene - Recent
Common Seal (Phoca vitulina)
Common Seal (Phoca vitulina)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Carnivora
Suborder: Caniformia
(unranked) Pinnipedia
Illiger, 1811
Families

Odobenidae (walruses)
Otariidae (fur seals and sea lions)
Phocidae (true seals)

Pinnipeds ("fin-feet", lit. The Oligocene is a geologic epoch of the Paleogene period and extends from about 33 Chordates ( Phylum Chordata) are a group of Animals that includes the Vertebrates together with several closely related Invertebrates Vertebrates are members of the Subphylum Vertebrata, Chordates with backbones or spinal columns The grouping sometimes includes Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands The diverse order Carnivora (kɑrˈnɪvərə or sometimes /ˌkɑrnɪˈvɔərə/ from Latin carō (stem carn-) "flesh" + vorāre Caniformia, or Canoidea (literally " dog-like " are a Suborder within the order Carnivora. In Biological classification, family ( Latin The walrus ( Odobenus rosmarus) is a large flippered Marine mammal with a discontinuous circumpolar distribution in the Arctic Ocean and The eared seals or otariids are Marine mammals in the family Otariidae - one of three groupings of Pinnipeds. The true seals or earless seals are one of the three main groups of Mammals within the seal Suborder, Pinnipedia. "winged feet") or fin-footed mammals are a widely distributed and diverse group of semi-aquatic marine mammals comprising the families Odobenidae (walruses), Otariidae (eared seals, including sea lions and fur seals), and Phocidae (true seals). Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands The walrus ( Odobenus rosmarus) is a large flippered Marine mammal with a discontinuous circumpolar distribution in the Arctic Ocean and The walrus ( Odobenus rosmarus) is a large flippered Marine mammal with a discontinuous circumpolar distribution in the Arctic Ocean and The eared seals or otariids are Marine mammals in the family Otariidae - one of three groupings of Pinnipeds. The eared seals or otariids are Marine mammals in the family Otariidae - one of three groupings of Pinnipeds. For other uses of the term "sea lion" see Sea lion (disambiguation. Fur seals are any of nine species of Pinnipeds in the Otariidae family The true seals or earless seals are one of the three main groups of Mammals within the seal Suborder, Pinnipedia. The true seals or earless seals are one of the three main groups of Mammals within the seal Suborder, Pinnipedia. Formerly classified as a separate biological suborder, Pinnipedia is now sometimes considered a superfamily within Caniformia, a suborder in the Carnivora order. This article is about the taxonomic rank for the sequence of species in a taxonomic list see Taxonomic order In scientific classification used Taxonomic rank ( rank, category, taxonomic category is an abstract term used in the Scientific classification, or Taxonomy, of organisms Caniformia, or Canoidea (literally " dog-like " are a Suborder within the order Carnivora. The diverse order Carnivora (kɑrˈnɪvərə or sometimes /ˌkɑrnɪˈvɔərə/ from Latin carō (stem carn-) "flesh" + vorāre

Contents

Evolution

Recent molecular evidence suggests that pinnipeds evolved from a bearlike ancestor about 23 million years ago during the late Oligocene or early Miocene epochs, a transitional period between the warmer Paleogene and cooler Neogene period. The Chattian (also known as Chickasawhayan or Late Oligocene) is the second and final of two stages of the Oligocene Epoch. The Oligocene is a geologic epoch of the Paleogene period and extends from about 33 The Miocene is a geological epoch of the Neogene period and extends from about 23 The Paleogene (alternatively Palaeogene) is a geologic period and system that began 65 The Neogene is a geologic period and system starting 2303 ± 0 [1] The earliest fossil pinniped that had been found is Enaliarctos, which lived 24 – 22 million years ago. Enaliarctos is an extinct genus of Pinniped. Five species in the genus Enaliarctos represent the oldest known pinniped fossils and have been recovered It is believed to have been a good swimmer, but to have been able to move on land as well as in water, more like an otter than like modern pinnipeds. There has been longstanding debate as to whether walruses diverged from a common otariid-phocid ancestor, or whether the phocids diverged before a common otariid-odobenid ancestor. The most recent evidence suggest that the latter hypothesis is more likely. [2]

Overview

Comparative anatomy of an otariid seal and a phocid seal.
Comparative anatomy of an otariid seal and a phocid seal.

Pinnipeds are typically sleek-bodied, barrel-shaped and can be rather large. Their bodies are well adapted to the aquatic habitat where they spend most of their lives. Their limbs have evolved into short, wide, flat flippers whence the name (derived from the Latin pinna = "feather", "wing" or "fin", and ped = foot). A flipper is typically flat limb evolved for movement through water Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. The smallest pinniped, the Galapagos fur seal, weighs about 30 kg (65 lb) when full-grown and is 1. The Galapagos Fur Seal ( Arctocephalus galapagoensis) breeds on the Galapagos Islands in the eastern Pacific west of Ecuador. The pound or pound-mass (abbreviation lb, lbm, or sometimes in the United States #) is a unit of Mass 2 m (4 ft) long; the largest, the male southern elephant seal, is over 4 m (13 ft) long and weighs up to 2,200 kg (4,850 lb, more than 2 tons). A foot (plural feet or foot; symbol or abbreviation ft or sometimes &prime – the prime symbol) is a non-SI unit The Southern Elephant Seal ( Mirounga leonina) is one of two Species of Elephant seal. Units of mass There are three similar units of Mass called the ton: Long ton (simply ton in countries such as the United

Otariidae

Eared seals, also called "walking seals" and "otariids", include the animals commonly known as sea lions and fur seals. The eared seals or otariids are Marine mammals in the family Otariidae - one of three groupings of Pinnipeds. For other uses of the term "sea lion" see Sea lion (disambiguation. Fur seals are any of nine species of Pinnipeds in the Otariidae family These are vocal, social animals that are somewhat better adapted to terrestrial habitats with rear flippers that can turn forward such that they can move on all fours on land. Their foreflippers are larger than those of earless seals and are used as a primary source of maneuverablity in the water. Eared seals have external ears, as their name suggests, and more dog-like snouts, further distinguishing them from the true seals. The pinna ( Latin for Feather) is the visible part of the Ear that resides outside of the head (this may also be referred to as the auricle or While sea lions are generally larger than fur seals and lack the dense underfur of the latter, the long-standing division into subfamilies (Arctocephalinae and Otariinae for fur seals and sea lions respectively) has been shown to be unjustified in light of recent genetic evidence suggesting that several fur seal species are more closely related to some sea lions than other fur seals. The iconic ball-balancing circus seal is generally some species of sea lion, most commonly a California sea lion. A circus is most commonly a traveling company of performers that may include acrobats, Clowns trained animals trapeze acts Hoopers, tightrope walkers The California Sea Lion ( Zalophus californianus) is a coastal Sea lion of the northern Pacific Ocean.

Phocidae

Earless seals, also called “true seals" or "phocids" are the most diverse and widespread of the pinnipeds. The true seals or earless seals are one of the three main groups of Mammals within the seal Suborder, Pinnipedia. They lack external ears and more streamlined snouts and are generally more aquatically adapted. They swim with efficient undulating whole body movements using their more developed rear flippers. The efficiency of their swimming and an array of other physiological adaptations make them better built for deep and long diving and long distance migrations. They are, however, very cumbersome on land, moving by wriggling their front flippers and abdominal muscles. True seals generally communicate by slapping the water and grunting, rather than vocalizing.

Odobenidae

The walrus is an exclusively Arctic species - the sole surviving member of the once diverse and widespread Odobenidae family. The walrus ( Odobenus rosmarus) is a large flippered Marine mammal with a discontinuous circumpolar distribution in the Arctic Ocean and The Arctic is the Region around the Earth 's North Pole, opposite the Antarctic region around the South Pole. They are easily recognized by their long tusks and great bulk (up to 2000 kg). While they share with otariids the ability to turn their rear flippers forward, their swimming is more reminiscent of that of true seals, relying more on sinuous whole body movements. They also lack external ears. Unlike eared seals and true seals, which feed primarily by hunting fish and squid in the water column, walrus generally prefer benthic invertebrates, in particular clams. The benthic zone is the ecological region at the lowest level of a Body of water such as an Ocean or a Lake, including the sediment surface and some sub-surface An invertebrate is an Animal lacking a Vertebral column. The group includes 98% of all animal Species — all animals except those in the Chordate Clam is a word which can be used for all some or only a few Species of Bivalve Mollusks the word is a Common name which has It is the development of the unique squirt and suck method of feeding on molluscs that differentiated the original walrus ancestor from the other pinniped lineages. There remains debate as to whether the walrus diverged from the eared seals before or after the true seals.

Adaptations

Flippers

Pinnipeds have shorter limbs than most other mammals. As noted above, their limbs have evolved into flippers with true seals having more developed hind flippers and eared seals having more developed fore flippers. The walrus is intermediate between the two. A pinniped’s fingers and toes are bound together by a web of skin. They also have claws that are found either on the front flippers (earless seals) or back flippers (eared seals). Because water has a much higher density than air, their flippers can be much smaller proportionately in relation to their size than the wings of a bird or bat. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different Additionally pinnipeds are essentially weightless in the water, allowing them to come to a standstill, and perform aquabatic feats in water that would be impossible for atmospheric flying creatures. Neutral buoyancy is a condition in which a physical body's mass equals the mass it displaces in a surrounding medium .

Pinnipeds can hold their breath for nearly two hours underwater
Pinnipeds can hold their breath for nearly two hours underwater

Oxygen conservation

Pinnipeds can conserve oxygen for long period of time underwater. When the animal starts diving its heart rate slows to about one-tenth of the normal rate. The arteries squeeze shut and the sense organs and nervous system are the only organs to continue to receive a normal flow of blood. Pinnipeds are able to resist more pain and fatigue caused by lactic acid accumulation than other mammals. However, once they return to the water surface, they need time to recover and bring their body chemistry back to normal. [3]

Warmth

To keep warm in cold waters, pinnipeds have a layer of blubber under their skin (which also provides buoyancy). The thickness depends on the species. Their blubber can also provide food for the animal. Newborn pinnipeds have no blubber.

Molting elephant seals at Año Nuevo State Park, California
Molting elephant seals at Año Nuevo State Park, California

Some pinnipeds can also can get warm from their fur. History The Quroste Ohlone Native Americans were the first people known to inhabit the Año Nuevo area The white coat of the infant harp seal, may trap the energy of sunlight as heat near the skin. The Harp Seal ( Phoca groenlandica; syn Pagophilus groenlandicus) is a species of earless seal native to the northernmost Atlantic As noted above, fur seal have underfur.

Molting

Like other mammals, pinnipeds have to shed their fur once in a while. Eared seals shed more slowly than earless seals. Most earless seals spend time in the water while molting.

Other adaptations

A pinniped’s eyes are well adapted for seeing both above and below the water. When diving the animal has a clear membrane that covers and protects its eyes. In addition, its nostrils close automatically. Testicles and mammary glands are located in slits under the skin to keep the pinniped’s streamlined shape. They also have whiskers to help navigate and sensors in their skull to absorb sounds underwater and trasmit them to the cochlea. The cochlea is the auditory portion of the Inner ear. Its core component is the Organ of Corti, the sensory organ of hearing, which is distributed along

Feeding

Teeth of a Crabeater seal
Teeth of a Crabeater seal

All pinnipeds are carnivorous, eating fish, shellfish, squid, and other marine creatures. The Crabeater Seal, Lobodon carcinophagus, is a little-known Mammal. A carnivore (ˈkɑrnɪvɔər meaning 'meat eater' ( Latin carne meaning 'flesh' and vorare meaning 'to devour' is any animal with a diet consisting Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two Shellfish is a Culinary and Fisheries term for those aquatic Invertebrate animals that are used as Food: various species of molluscs Squid are marine Cephalopods of the order Teuthida, which comprises around 300 species Most are generalist feeders, but some are specialists. For example; Ross Seals and Southern elephant seals mainly feed on squid. The Ross Seal ( Ommatophoca rossii) is a carnivorous seal of the family Phocidae and only species of the genus Ommatophoca. The Southern Elephant Seal ( Mirounga leonina) is one of two Species of Elephant seal. Crabeater seals eat mostly krill, and Ringed seals feed almost exclusively on crustaceans. The Crabeater Seal, Lobodon carcinophagus, is a little-known Mammal. Structure of crustaceans As Arthropods crustaceans have a stiff Exoskeleton, which must be shed to allow the animal to grow ( Ecdysis or molting Additionally, the Walrus consumes molluscan prey items by sucking the soft parts from the shell. The walrus ( Odobenus rosmarus) is a large flippered Marine mammal with a discontinuous circumpolar distribution in the Arctic Ocean and

Some seals will even eat warm-blooded prey including other seals. The leopard seal, which is probably the most carnivorous and predatory of all the pinnipeds, will eat penguins as well as Crabeater and Ross Seals. The Leopard seal ( Hydrurga leptonyx) is the second largest species of seal in the Antarctic (after the Southern Elephant Seal) and is near the top Penguins ( order Sphenisciformes, family Spheniscidae) are a group of aquatic, flightless Birds living almost The South American sea lion also eats penguin as well as flying seabirds and young South American fur seals. Otaria redirects here If you are looking for the continent in Magic The Gathering, see Otaria. The South American Fur Seal ( Arctocephalus australis) is a species of Fur seal that breeds on the coasts of Chile and Argentina. Steller sea lions have been recorded eating Northern fur seal pups, Common seal pups and birds. The Steller sea lion, Eumetopias jubatus, also known as the northern sea lion, is a Sea lion of the northern Pacific. The Northern Fur Seal, Callorhinus ursinus, is an Eared seal found along the north Pacific Ocean, the Bering Sea and the Sea of Okhotsk

Almost all pinnipeds are potential prey for orcas and larger sharks. The Orca or Killer Whale ( Orcinus orca) less commonly Blackfish or Seawolf, is the largest species of the Oceanic dolphin family Arctic species are an important component of polar bear diet. The polar bear ( Ursus maritimus) is a Bear native to the Arctic Ocean and its surrounding seas

Reproduction

Galápagos sea lion (Zalophus wollebaeki) pup.
Galápagos sea lion (Zalophus wollebaeki) pup. UserPolbot. --> The Galápagos Sea Lion ( Zalophus wollebaeki) is a species of Mammal in the Otariidae

Pinnipeds often come ashore or haul out on ice to breed, often travelling long distances from their feeding grounds to suitable mating grounds with a high level of reproductive synchrony. In Biology, mating is the pairing of opposite- Sex or hermaphroditic Organisms for copulation and in Social animals also to raise their Reproductive synchrony, or synchronous spawning is a term used in Evolutionary biology and behavioural ecology to describe the way in which many species Almost all pinnipeds are polygynous, i. Polygyny (which comes from neo- Greek: πολύ poly "many" + γυνή gyny "woman" is a specific form of Polygamy, e. males breed with up to several dozen females in a season. Males of many species, (e. g. elephant seals, South American sea lions and Northern fur seals) aggressively defend groups of specific females, referred to as harems. Elephant seals are large oceangoing Mammals in the Genus Mirounga, in the Earless seal (Phocidae family. Otaria redirects here If you are looking for the continent in Magic The Gathering, see Otaria. The Northern Fur Seal, Callorhinus ursinus, is an Eared seal found along the north Pacific Ocean, the Bering Sea and the Sea of Okhotsk HAREM is the first evaluation contest of Named entity recognition (NER for Portuguese and its call for participation was announced in September 2004 Males of other species (e. g. most sea lions and Cape fur seals) defend territories on reproductive rookeries while females move freely between them. Some form of competition, either for females or territories, some of which can be violent, is an integral part of the male breeding strategy among most pinnipeds. Otariids, which are generally more land-adapted, tend to form major aggregations in the summer months on beaches or rocky outcrops. Consequently, their reproductive behavior is easier to observe and well studied. Walruses and many phocids, on the other hand, tend to form smaller aggregations, often in remote locations or on ice, and copulate in the water. Their reproductive behavior is therefore generally less well known.

Females have a postpartum oestrus allowing them to mate soon after giving birth. Postnatal ( Latin for 'after birth' from post meaning "after" and natalis meaning "of birth" is the period beginning immediately after Oestrus is also the biological genus name of the gadfly. The estrous cycle (also oestrous cycle; derived from Latin Subsequent implantation of the embryo is delayed (embryonic diapause) thus removing the need to come ashore (haul-out) twice, once to give birth and again later to mate. An embryo (from Greek:, plural, lit "that which grows" from en- "in" + bryein "to swell be full" is a multicellular Embryonic diapause or Delayed implantation is a reproductive strategy used by close to 100 different Mammals in seven different orders. After giving birth, mothers suckle their young for a variable length of time. Amongst the phocids, lactation varies from 4 to 50 days, whereas the otarids may lactate from 4 to 36 months. This reflects the fact that phocid feeding grounds tend to be a long way off-shore, so lactation is associated with maternal fasting. Fasting is primarily the act of willingly abstaining from some or all Food, Drink, or both for a period of time To compensate for the short lactation period, the fat content of phocid milk is higher than in any other species of marine mammal (45 – 60% fat). Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water Milk is an opaque white liquid produced by the Mammary glands of female Mammals (including Monotremes. After lactation most female phocids make extensive migratory movements to feeding grounds for intensive foraging to recoup depleted energy reserves. Lactation describes the secretion of Milk from the Mammary glands the process of providing that milk to the young and the period of time that a Mother On the other hand, otarid feeding grounds are generally closer to shore and females go on foraging trips to maintain lactation. Fat content of otarid milk is lower than that of the phocids, owing to the protracted lactatory period (typically 25 – 50%). Protracted nursing also leads to the formation of social bonds.

Taxonomy

Common Seal or Harbor Seal (Phoca vitulina) underwater
Common Seal or Harbor Seal (Phoca vitulina) underwater

In culture

Seals, sea lions, and walruses are popular animals in the media. The true seals or earless seals are one of the three main groups of Mammals within the seal Suborder, Pinnipedia. The Hawaiian monk seal, Monachus schauinslandi, is an endangered Earless seal that is endemic to the waters off of the Hawaiian Islands The Mediterranean Monk Seal ( Monachus monachus) is believed to be the world's rarest Pinniped and one of the most endangered Mammals of the world The Caribbean Monk Seal or West Indian Monk Seal ( Monachus tropicalis) is an Extinct species of seal. The Northern Elephant Seal ( Mirounga angustirostris) is one of two Species of Elephant seal (the other is the Southern Elephant Seal) The Southern Elephant Seal ( Mirounga leonina) is one of two Species of Elephant seal. The Ross Seal ( Ommatophoca rossii) is a carnivorous seal of the family Phocidae and only species of the genus Ommatophoca. The Crabeater Seal, Lobodon carcinophagus, is a little-known Mammal. The Leopard seal ( Hydrurga leptonyx) is the second largest species of seal in the Antarctic (after the Southern Elephant Seal) and is near the top The Weddell Seal ( Leptonychotes weddellii) is a True seal that occurs in large numbers and inhabit the circumpolar region of the Southern hemisphere, including Acrophoca longirostris is an extinct species of Pinniped whose fossils have been discovered in Peru and Chile. The Bearded Seal ( Erignathus barbatus) also called the Square Flipper Seal, is a medium-sized Pinniped that is found in and near to the Arctic The Hooded Seal ( Cystophora cristata) is an Arctic Pinniped found only in the central and western North Atlantic ranging from Svalbard The Spotted Seal ( Phoca largha) also known as the Larga Seal, inhabits the ice and waters of the north Pacific Ocean and adjacent seas The Ringed Seal ( Pusa hispida) also known as the Jar Seal and as Netsik or Nattiq by the Inuit, is an Earless seal inhabiting Nerpa may refer to Baikal Seal Nerpa Nepal Caspian seals ( Pusa caspica) one of the smallest members of the " True seal " family are unique in that they are found exclusively in the brackish Caspian The Harp Seal ( Phoca groenlandica; syn Pagophilus groenlandicus) is a species of earless seal native to the northernmost Atlantic The Ribbon Seal ( Histriophoca fasciata) is a Pinniped from the True seal family (Phocidae They are often portrayed balancing beach balls on their noses and clapping with their flippers.

Notable fictional seals include:

Because of the creature's name being coincidentally spelled the same as the unrelated word "seal" for a stamp, the confusion of one with the other is an occasional comic gag, as in "Christmas seal", or the live seal produced by Harpo Marx in Horse Feathers when Groucho Marx tries to find the legal seal for a contract document. At the core of the multi-billion dollar Pokémon Media franchise of various electronic games, ongoing anime, several manga series, Arthur Marx (previously Adolph Marx) popularly known as Harpo Marx ( November 23, 1893 &ndash September 28, 1964 Horse Feathers ( 1932) was the fourth Marx Brothers Film. It stars the four Marx Brothers Groucho, Chico, Harpo

Notable fictional walruses include:

At least three professional sports teams in the San Francisco, California, area have been known as the "Seals". The City and County of San Francisco is the fourth most populous city

See also

References

  1. ^ John J. The Order Cetacea (sɪˈteɪʃiə L cetus, whale includes Whales Dolphins and Porpoises Cetus is Not to be confused with order Sirenidae (aquatic salamanders For the Gothic metal band see Sirenia (band Sirenia Nothosaurs (order Nothosauroidea) were Triassic marine Sauropterygian Reptiles that may have lived like seals of today catching Vocal Learning is the ability of Animals to modify vocal signals in form as a result of experience with those of other individuals Flynn et al (2005). "Molecular Phylogeny of the Carnivora". Systematic Biology 54: 317 – 337.  
  2. ^ Ulfur Arnason , Anette Gullberg, Axel Janke, et al (2006). "Pinniped phylogeny and a new hypothesis for their origin and dispersal". Molecular Phylogenetics and Evolution 41: 345–354.  
  3. ^ Encarta article on Seals
 The subject of this article has been identified by the Missing Encyclopedic Articles project as being a high priority for expansion.

Dictionary

pinniped

-noun

  1. Any of various large marine mammals belonging to the former suborder Pinnipedia comprising walruses, eared seals and earless seals.

-adjective

  1. Pertaining to such a mammal.
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