Hydrurga leptonyxleopard seal

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Geographic Range

Leopard seals (Hydrurga leptonyx) are predominately found in the circumpolar region of the Antarctic pack ice. Although small numbers can be found just beyond the pack ice on the nearby subantarctic islands year-round, there is greater dispersal into this area during the winter months. (Oritsland, 1970; Rogers, 2009)

Habitat

Leopard seals reside mostly on and around the pack ice of Antarctica, but may also be seen on the subantarctic islands if there is enough ice substrate. These seals are much more agile in the water than on ice, and water is where they spend much of their time. Leopard seals feed on species that reside in the surface waters of the ocean, and thus are found primarily in these waters. (Jessopp, et al., 2004; Laws, 1984; Oritsland, 1970)

  • Terrestrial Biomes
  • icecap

Physical Description

Leopard seals are by far the largest of the antarctic seals. Males can grow up to 3 meters in length and weigh approximately 300 kg. Females are even larger, growing up to 3.8 meters in length and 500 kg. The overall body shape of leopard seals are long and slender, making it very agile in the water. Their coloring varies dorsally to ventrally with a dark grey back, a silvery grey underside, and dark and light spots throughout the entire body. The snout of leopard seals are long on their large head; well-designed for catching and handling prey. (Ray, 1970; Rogers, 2009)

  • Sexual Dimorphism
  • female larger
  • Range mass
    300 to 500 kg
    660.79 to 1101.32 lb
  • Range length
    3 to 3.8 m
    9.84 to 12.47 ft

Reproduction

Little is known about leopard seal mating systems, because they inhabit an extreme environment making direct observation difficult. Much of what is known was observed from captive individuals. Little is known about mate acquisition in leopard seals, but vocalization is thought to play a role as males become highly vocal during the breeding season. Mating occurs in the water in captive environments and wild populations are thought to behave similarly. After mating the female is left alone to wean the pups on the ice. (Rogers, 2009)

Birth of leopard seal pups generally occurs between late October and November, with newborn pups measuring on average 120 cm in length. For the next 4 weeks, the mother nurses her pups on an ice flow. Mating occurs during December and into the beginning of January shortly after the pups are weaned. (Jefferson, et al., 1993; Oritsland, 1970; Rogers, 2009; Siniff, 1991)

  • Breeding interval
    Leopard seals breed once yearly.
  • Breeding season
    The breeding lasts from December to early January.
  • Range number of offspring
    1 (high)
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Average gestation period
    274 days
    AnAge
  • Range weaning age
    4 (high) weeks
  • Average age at sexual or reproductive maturity (female)
    4 years
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    1095 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    4.5 years
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    1461 days
    AnAge

Leopard seals live a solitary life with the exception of a brief mating period, so there is little information describing mating interactions of males and females. It is, however, known that males do not provide any post-fertilization parental investment once they have mated with a female. (Rogers, 2009)

Female leopard seals are solely responsible for their pup once it is born. On the ice floes of Antarctica mother seals are seen nursing and protecting their young for approximately 4 weeks following birth. After these 4 weeks, the pup is weaned and shortly after females begin mating again. After the weaning period, there is not much known about leopard seal development. Juvenile leopard seals have, however, been observed in relatively large numbers on the nearby subantarctic islands. (Rogers, 2009; Siniff, 1991)

  • Parental Investment
  • female parental care
  • pre-fertilization
    • provisioning
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

There are few accounts of the lifespan of leopard seals. However, they have been recorded to live for up to 30 years in the wild, but the lifespan is speculated to be closer to 26 years. (Oritsland, 1970; Rogers, 2009)

Behavior

Leopard seals are a solitary species excluding mating and nursing periods. As mating season approaches, the density of seals on and around packs of ice increases. Density on pack ice also increases when pups are born, as that is where mothers give birth and nurse their young. Otherwise leopard seals predominately inhabit the water. (Laws, 1984; Rogers, 2009; Siniff, 1991)

Home Range

The home range of leopard seals is confined mostly to the pack ice, because of mating. Throughout the year are also found on the nearby subantarctic islands in moderately low numbers. However, this greatly increases during the winter months during the seal migration period. (Jessopp, et al., 2004; Oritsland, 1970; Rogers, 2009)

Communication and Perception

Not much is known regarding communication among leopard seals. However, males are known to vocalize just prior to and during the mating season. It is suspected that these sounds are used for mate attraction. (Opzeeland, et al., 2010)

Food Habits

Leopard seals feed primarily on krill, using their lobodont teeth to filter these small crustaceans from the water. Although krill are their primary food source, leopard seals are also aggressive apex predators eating penguins, young crabeater seals, and squid. (Berkman, 2001; Rogers, 2009)

  • Animal Foods
  • birds
  • mammals
  • fish
  • mollusks
  • aquatic crustaceans

Predation

Leopard seals are apex predators, indicating that they are at the top of the Antarctic food chain. Their only known natural predators are killer whales, however leopard seals are rarely eaten. (Berkman, 2001)

Ecosystem Roles

As apex predators, leopard seals play an important ecological role feeding on large animals that inhabit the extreme antarctic system. (Rogers, 2009)

Economic Importance for Humans: Positive

There are few interactions between humans and leopard seals, however they are used for scientific research and education. (Jefferson, et al., 1993)

  • Positive Impacts
  • research and education

Economic Importance for Humans: Negative

Leopard seals have no observed negative economic effects on humans. (Jefferson, et al., 1993)

Conservation Status

According to the IUCN Red List, leopard seals are at lower risk and of least concern. However, a decline in antarctic pack ice will likely to be impact the species. ("2008 Pacific islands red list for animals", 2008)

Other Comments

The scientific name of leopard seals, Hydrurga leptonyx, literally translated means 'slender-clawed water-worker'. (Rogers, 2009)

Contributors

Anna Hill (author), Michigan State University, Barbara Lundrigan (editor), Michigan State University, Laura Podzikowski (editor), Special Projects.

Glossary

Antarctica

lives on Antarctica, the southernmost continent which sits astride the southern pole.

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

filter-feeding

a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

migratory

makes seasonal movements between breeding and wintering grounds

molluscivore

eats mollusks, members of Phylum Mollusca

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

polar

the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.

polygynous

having more than one female as a mate at one time

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

2008. "2008 Pacific islands red list for animals" (On-line). IUCN.org. Accessed March 11, 2012 at http://cmsdata.iucn.org/downloads/appendix_1_animals_of_the_pacific_islands_listed_on_the_2008_red_list.pdf.

Berkman, P. 2001. Science into Policy : Global Lessons from Antarctica. Burlington, MA: Academic Press.

Jefferson, T., S. Leatherwood, M. Webber. 1993. Marine Mammals of the World. Roome: United Nations Environment Programme, Food and Agriculture Organization of the United Nations.

Jessopp, M., J. Reid, P. Trathan, E. Murphy. 2004. Winter dispersal of leopard seals (Hydrurga leptonyx): environmental factors influencing demographics and seasonal abundance. Journal of Zoology, 263: 251-258.

Laws, R. 1984. Antarctic Ecology Vol. II. London: Academic Press.

Opzeeland, I., S. Parijs, H. Bornemann, S. Frickenhaus, L. Kindermann, H. Klinck, J. Plotz, O. Boebel. 2010. Acoustic ecology of Antarctic pinnipeds. Marine Ecology Progress Series, 414: 267-291.

Oritsland, T. 1970. Biology and Population Dynamics of Antarctic Seals. Pp. 361-366 in M Holdgate, ed. Antarctic Ecology, Vol. I. London: Academic Press.

Ray, C. 1970. Population Ecology of Antarctic Seals. Pp. 398-414 in M Holdgate, ed. Antarctic Ecology, Vol. 1. London, New York: Academic Press.

Rogers, T. 2009. "Leopard seal (H. leptonyx)" (On-line). The Society for Marine Mammalogy. Accessed March 11, 2012 at http://www.marinemammalscience.org/index.php?option=com_content&view=article&id=459&Itemid=298.

Siniff, D. 1991. An Overview of the Ecology of Antarctic Seals. American Zoologist, 31: 143-149.