Changes

==Description==

==Description==

Seals on average are generally smaller than the other two families of Pinnipedia ([[sea lion]]s and [[walrus]]), but they include both the smallest and largest members of the suborder.  The smallest species are Baikal<ref>http://www.conservenature.org/learn_about_wildlife/marine_mammals/baikal_seal.htm</ref> and ringed seals<ref>https://www.nationalgeographic.com/animals/mammals/r/ringed-seal/</ref> with lengths between 43.3 and 55.1 inches and a weight of just over 110 pounds. The largest species on record is the southern elephant seal, whose bulls can be 21.3 feet long and over five tons in weight<ref>https://www.nationalgeographic.com/animals/mammals/group/elephant-seals/</ref>. There is very little sexual dimorphism among the species, with the elephant seals a major exception, as bulls are roughly three times larger than females.

Seals on average are generally smaller than the other two families of Pinnipedia ([[sea lion]]s and [[walrus]]), but they include both the smallest and largest members of the suborder.  The smallest species are Baikal<ref>http://www.conservenature.org/learn_about_wildlife/marine_mammals/baikal_seal.htm</ref> and ringed seals<ref>https://www.nationalgeographic.com/animals/mammals/r/ringed-seal/</ref> with lengths between 43.3 and 55.1 inches and a weight of just over 110 pounds. The largest species on record is the southern elephant seal, whose bulls can be 21.3 feet long and over five tons in weight.<ref>https://www.nationalgeographic.com/animals/mammals/group/elephant-seals/</ref>  There is very little sexual dimorphism among the species, with the elephant seals a major exception, as bulls are roughly three times larger than females.

The body shape is designed for effortless swimming.  The head is small compared to the body, and noticeably tapers in front.  External ears are absent. On the upper lip there are 6-10 rows of whiskers, less rigid than those of the walrus. The tail is short but well pronounced. Front flippers make up less than 25% of body length and are noticeably smaller than the hind ones. The rear flippers are always extended backwards; they do not bend at the hip and cannot serve as a support when moving overland, giving seals a "caterpillar"-like form of locomotion when on land.  At sea, however, movement is very fish-like and efficient, with side-to-side sweeps of the rear flippers.  

The body shape is designed for effortless swimming.  The head is small compared to the body, and noticeably tapers in front.  External ears are absent. On the upper lip there are 6-10 rows of whiskers, less rigid than those of the walrus. The tail is short but well pronounced. Front flippers make up less than 25% of body length and are noticeably smaller than the hind ones. The rear flippers are always extended backwards; they do not bend at the hip and cannot serve as a support when moving overland, giving seals a "caterpillar"-like form of locomotion when on land.  At sea, however, movement is very fish-like and efficient, with side-to-side sweeps of the rear flippers.  

==Range and diet==

==Range and diet==

Most of the species are distributed in cold and temperate waters along coastlines north of 30° latitude in the northern hemisphere, and south of 50° latitude in the southern hemisphere.  A few species live in tropical waters, while two inhabit freshwater lakes in Russia, in particular, lakes Baikal<ref>https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/baikal-seal</ref> and Ladoga<ref>http://pubs.aina.ucalgary.ca/arctic/Arctic66-4-417.pdf</ref>.

Most of the species are distributed in cold and temperate waters along coastlines north of 30° latitude in the northern hemisphere, and south of 50° latitude in the southern hemisphere.  A few species live in tropical waters, while two inhabit freshwater lakes in Russia, in particular, lakes Baikal<ref>https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/baikal-seal</ref> and Ladoga.<ref>http://pubs.aina.ucalgary.ca/arctic/Arctic66-4-417.pdf</ref>

They feed on fish, cephalopod mollusks and crustaceans, and krill<ref>https://seaworld.org/animals/all-about/harbor-seal/diet/</ref><ref>https://animalcorner.co.uk/animals/common-seal/</ref><ref>http://www.smru.st-andrews.ac.uk/files/2016/08/Seal-Diet-Leaflet.pdf</ref>; leopard seals feed on warm-blooded prey, attacking penguins and other seals<ref>http://www.antarctica.gov.au/about-antarctica/wildlife/animals/seals-and-sea-lions/leopard-seals</ref>. Seals can dive very well in search of food, with the Weddell seal reaching depths in excess of 1,800 feet, remaining under water for more than an hour<ref>https://www.nationalgeographic.com/animals/mammals/w/weddell-seal/</ref><ref>http://www.antarctica.gov.au/about-antarctica/wildlife/animals/seals-and-sea-lions/weddell-seals</ref>.

They feed on fish, cephalopod mollusks and crustaceans, and krill;<ref>https://seaworld.org/animals/all-about/harbor-seal/diet/</ref><ref>https://animalcorner.co.uk/animals/common-seal/</ref><ref>http://www.smru.st-andrews.ac.uk/files/2016/08/Seal-Diet-Leaflet.pdf</ref> leopard seals feed on warm-blooded prey, attacking penguins and other seals.<ref>http://www.antarctica.gov.au/about-antarctica/wildlife/animals/seals-and-sea-lions/leopard-seals</ref>  Seals can dive very well in search of food, with the Weddell seal reaching depths in excess of 1,800 feet, remaining under water for more than an hour.<ref>https://www.nationalgeographic.com/animals/mammals/w/weddell-seal/</ref><ref>http://www.antarctica.gov.au/about-antarctica/wildlife/animals/seals-and-sea-lions/weddell-seals</ref>  

==Reproduction==

==Reproduction==

Most seals pair-bond during breeding, while elephant seal bulls have extended harems of 20 or more females which they defend from other bulls<ref>http://www.marinebio.net/marinescience/05nekton/esrepro.htm</ref>. The duration of pregnancy is 270-350 days.  Nursing females in search of food swim far into the sea, unlike the female eared seals, which are kept near the shore. Feeding usually stops when the baby is not yet able to feed on its own, and from age 2 to 9-12 weeks it survives on accumulated fat reserves.

Most seals pair-bond during breeding, while elephant seal bulls have extended harems of 20 or more females which they defend from other bulls.<ref>http://www.marinebio.net/marinescience/05nekton/esrepro.htm</ref>  The duration of pregnancy is 270–350 days.  Nursing females in search of food swim far into the sea, unlike the female eared seals, which are kept near the shore. Feeding usually stops when the baby is not yet able to feed on its own, and from age 2 to 9–12 weeks it survives on accumulated fat reserves.

==References==

==References==

[[Category:Mammals]][[Category:Marine Mammals]][[Category:Carnivora]]

[[Category:Mammals]][[Category:Marine Mammals]][[Category:Carnivora]]