Monk Seals

Monk Seals



COMMON NAME: monk seals
KINGDOM: Animalia
PHYLUM: Chordata
CLASS: Mammalia
ORDER: Pinnipedia
FAMILY: Phocidae
GENUS SPECIES: Monachus spp. (Comes from the Greek word monakhos, meaning "monk" or "solitary")


DESCRIPTION: Monk seals belong to the pinniped family Phocidae (true seals). Seals differ from sea lions (eared seals) in a number of ways, including having shorter, stouter flippers, and no visible earflaps. Monk seals tend to be dark brown to grayish brown on the dorsal side and lighter yellow to whitish ventrally. Pups of both species are blackish in color. Monk seals, along with bearded seals, are the only phocids that have two pairs of abdominal mammae.
SIZE: Mediterranean monk seals can measure up to 2.8 m (9.2 ft.), with no size difference between males and females. Hawaiian monk seal adult males are slightly smaller than females.

Newborn Mediterranean pups average lengths of 85-110 cm (33-43 in.) while Hawaiian monk seal pups may be 1 m (3.4 ft.) long at birth.
MALE Mature male Hawaiian monk seals may reach maximum lengths of 2.1 m (6.9 ft.).
FEMALE Hawaiian monk seal adult females may measure as much as 2.4 m (7.75 ft.).
WEIGHT: Adult Mediterranean monk seals can weigh 240-400 kg (529-881 lb.) and pups of both species weigh as much as 16-18 kg (35-40 lbs.).
MALE Adult Hawaiian monk seal males can weigh up to 230 kg (510 lb.).
FEMALE Hawaiian monk seal adult females may weigh as much as 270 kg (595 lb.).
DIET: Hawaiian monk seals feed primarily on reef fishes, eels, octopuses, and lobsters. Mediterranean monk seals feed on a variety of fishes and octopuses.
GESTATION: May be about 11 months for both species.
ESTRAL PERIOD Hawaiian Monk seals unusually long breeding season lasts from December to mid-August, but most pups are born from March to June.
NURSING DURATION 5-6 weeks; In Mediterranean monk seals possibly as much as 16-17 weeks in some rare cases.
SEXUAL MATURITY: 4-6 years for both species
LIFE SPAN: Probably 25-30 years for both species.
RANGE: Hawaiian monk seals are found throughout the northwestern chain of the outermost Hawaiian Islands and occasionally on the main island group.

Once abundant throughout the Mediterranean Sea, the southern Black Sea, and the northwestern coast of Africa, the Mediterranean monk seals are now scattered through just a small part of their historical range.
HABITAT: Both species inhabit coastal areas. When Mediterranean monk seals haul out, they usually prefer caves or grottos, some with underwater entrances. Hawaiian monk seals typically haul out on sandy beaches.
POPULATION: GLOBAL An estimated 500-1,000 individuals are all that remain of the Mediterranean monk seal, and there are probably only 1,300-1,400 Hawaiian monk seals remaining.
STATUS: IUCN The Mediterranean monk seal is listed as Critically Endangered, the Caribbean monk seal is regarded as Extinct, and the Mediterranean monk seal is listed as Endangered.
CITES Both the Mediterranean monk seal and the Mediterranean monk seal Appendix I. The Caribbean monk seal is listed as Extinct.
USFWS The Hawaiian monk seal is listed as endangered


1. There are two living species of monk seals: Hawaiian monk seal (Monachus schauinslandi) and Mediterranean monk seal (Monachus monachus). A third species, the Caribbean monk seal (Monachus tropicalis) is believed to be extinct-no individuals have been observed since the early 1950s.
2. Scientists believe Hawaiian monk seals to be "living fossils". The anatomy, behavior and physiology of this species of monk seal is only slightly different from monk seals that ranged along the eastern coast of the United States 14-16 million years ago.
3. Mediterranean monk seals are one of the least social pinnipeds when they are on shore, but may be more social in the water. These are considered one of the most critically endangered species of mammal in the world.
4. Tiger sharks often prey upon Hawaiian monk seals as evidenced by shark bite wounds present on many monk seals. Other shark predators include gray reef and white-tipped reef sharks. Predation by sharks possibly helps explain why female Hawaiian monk seals seem to prefer beach sites adjacent to shallow water on which to give birth and raise their pups.


Both Mediterranean and Hawaiian monk seals are endangered. Researchers estimate that the population has declined 60% since the late 1950s. Threats to monk seals are widespread and numerous. All three species of monk seals have suffered a long history of commercial hunting. Pollution and human development have also posed serious threats to monk seal populations. Hawaiian monk seals also succumb to lack of prey, tiger shark attacks, and even violent mobbing interactions with each other.

Monk seals are protected by the Endangered Species Act of 1973 (ESA). Hawaiian monk seals are also protected by the Marine Mammal Protection Act of 1972 and by other federal and local legislation.


Byrum, J. Pinnipeds From Pole to Pole: Seals, Sea Lions and Walruses. SeaWorld Education Department Publication. San Diego. SeaWorld, Inc. 2000.

Jefferson, T.J. Leatherwood, S. and M.A. Webber. FAO Species Identification Guide. Marine Mammals of the World. Rome. FAO, 1993.

Rauzon, M.J. Isles of Refuge: Wildlife and History of the Northwestern Hawaiian Islands. Honolulu. University of Hawai'i Press. 2001.

Reeves, R.R., Stewart, B.S. and S. Stephen. The Sierra Club Handbook of Seals and Sirenians. San Francisco: Sierra Club Books, 1992.

Reeves, R. R., Stewart, B.S., Clapman, P.J., and J.A. Powell (Peter Folkens illustrator). National Audubon Society: Guide to Marine Mammals of the World. New York: Random House, 2002.

Riedman, M. The Pinnipeds: Seals, Sea Lions and Walruses. Berkeley and Los Angeles. University of California Press. 1990. IUCN Animal Info-Mediterranean Monk Seal