Ribbon seals most frequently inhabit the Bering Sea and the Sea of Okhotsk. Both are located near southern Russia, just north of Korea and Japan. The southern-most limit of the ribbon seal range extends as far south as the Aleutian Islands, a chain of volcanic islands located just west of the Alaska Peninsula. The northern-most portion of their range extends to the Chukchi Sea, between Alaska and Siberia. Ribbon seals have been reported as far west as the Beaufort Sea, just beyond the limits of Alaska. Solitary ribbon seals also have been observed along the coast of California. ("Status Review of the Ribbon Seal (Histriophoca fasciata)", 2008; Burns, 1970; MacDonald and Cook, 2009; Macdonald, 2006)
Little is known about the extent of ribbon seal migration. During the breeding season, ribbon seals sometimes migrate to southern portions of the Chukchi Sea. They also are seen frequently in northern portions of the Bering Sea. (Burns, 1970; Macdonald, 2006)
Ribbon seals prefer to remain near food sources, rather than traveling long distances to locate prey. Areas with broken ice chunks support constantly circulating water, which helps to create a stable food source. Ribbon seals can dive to depths of 600 m to obtain food. ("Status Review of the Ribbon Seal (Histriophoca fasciata)", 2008; Fedoseev, 2002; MacDonald and Cook, 2009; Macdonald, 2006; Mizuno, et al., 2002; Simpkins, et al., 2003)
Ribbon seals are found in the Okhotsk Sea, a region that is typically 80 to 90% covered with ice. It is believed that ribbon seals use this area for breeding. Breeding rookeries help reduce predation by larger marine mammals, as many lack the ability to pull themselves onto the thick ice. ("Status Review of the Ribbon Seal (Histriophoca fasciata)", 2008; Fedoseev, 2002; MacDonald and Cook, 2009; Macdonald, 2006; Mizuno, et al., 2002; Simpkins, et al., 2003)
The respiratory system of ribbon seals is unique, they lack lobes in the lungs. These lobes, common in other species, create multiple lung sections divided by thin walls of tissue. Ribbon seals have well-developed air sacs, believed to help with buoyancy and production of sounds. These air sacs do not form until maturation and are considerably smaller in females than in males. (Fedoseev, 2002)
Like other pinnipeds, ribbon seals have cylindrical bodies with limbs modified for swimming. Newborn ribbon seals are white. Body color changes gradually with maturity, with adult males becoming reddish-brown until they molt or shed. After molting, the male coat changes to black. Females are usually lighter than males. Ribbon seals are easily distinguished from other phocids by their unique white bands over their bodies. Markings begin to appear as early as 12 weeks old, although they usually are not distinct until after the seal molts. Each ribbon seal has four white bands, creating a pronounced black and white pattern. One band is around the neck, one around each of the fore-flippers, and one around the lower back before the hind-flippers. The size and exact location of each band varies from seal to seal. These markings are usually more distinct in males than in females. ("Status Review of the Ribbon Seal (Histriophoca fasciata)", 2008; Fedoseev, 2002; Macdonald, 2006; Renouf, 1991; Roest, 1964)
Three developmental stages are recognized in ribbon seals. Newborns typically range in body length from 73 to 98 cm, with a weight of 6 to 10 kg. Juveniles have a body length of 128 to 134 cm, with a weight of 40 to 50 kg. At about 2 to 3 years old, ribbon seals are considered adults, with a body size of roughly 145 to 155 cm and weight of 55 to 70 kg. Over the next few years, ribbon seals continue to grow and can reach a maximum length of 165 to 175 cm and weight of 72 to 90 kg. This increase is due to continuing development and additional accumulation of blubber, as well as changes after reproduction. (Fedoseev, 2002)
Another distinguishing feature of ribbon seals is a higher percentage of body weight attributable to vital organ volume. Major organs contribute to body weight as follows: 22% liver, 17% lungs, 8% heart, 7% diaphragm, and 2.7% kidneys. This is believed to help increase their diving and swimming abilities. (Fedoseev, 2002)
Ribbon seals typically mate in rookeries established on sea ice. Like most true seals, ribbon seals are polygynous. Male ribbon seals use their air sac for vocalizations or phonation during mating, both to attract mates and to establish or defend territories. (Macdonald, 2006)
Male ribbon seals reach reproductive maturity at approximately three to six years of age. Females typically mature earlier, between two to five years of age. Ribbon seals undergo delayed implantation for two to four months. This allows them to wait until sufficient sea ice is present for birthing. Breeding season usually begins in late May, with breeding centering around the annual breakup of ice each spring. Differences in ice conditions affect the duration of pup rearing and the size of individual pups. (Atkinson, 1997; Fedoseev, 2002; Macdonald, 2006)
Female ribbon seals have a gestation period of about 11 months, after which they give birth to a single pup, usually in April. It is rare for females to give birth to two pups. When this occurs, one usually does not survive. Females give birth and raise pups on packed ice. Pups average 73 to 98 cm long and 6 to 10 kg in body weight. Females nurse pups for four to six weeks, after which pups are weaned. Milk for the young is rich in proteins and fats which helps to rapidly increase the weight of the pup. After weaning, adults are able to mate again the following year. (Fedoseev, 2002; Macdonald, 2006)
Female ribbon seals expend considerable energy on parental care, particularly energy for feeding and defending pups from adult males and potential predators. During lactation, females undergo a short fasting period in which they do not leave their pup. After the nursing period, females help pups to become independent by teaching them to dive for food. (Fedoseev, 2002; Macdonald, 2006)
Ribbon seals typically live for 25 to 30 years in the wild. Ribbon seal age can be determined roughly by examining the horn covers on the front claws and the layers found on the tip of the tusks. Little is known about the lifespan of ribbon seals in captivity. (Fedoseev, 2002; Weigl, 2005)
Ribbon seals are diurnal, when they forage for food. Ribbon seals generally occur in small groups. The majority of their time is spent in the water foraging and migrating between breeding areas and areas of lighter sea ice. During the breeding season, ribbon seals of all ages, genders, and sizes are found together. Breeding and molting season overlap, both happening during the spring ice breakup. Adult seals come to the ice in order to breed while juveniles use the ice as a site for molting. ("Status Review of the Ribbon Seal (Histriophoca fasciata)", 2008; Fedoseev, 2002; MacDonald and Cook, 2009; Macdonald, 2006)
Ribbon seal females leave their pups alone for extended periods of time, unlike most true seals. A probable reason for this behavior is their relative lack of predators. This is because they rear their pups on thinning ice, which creates a barrier for many predators. ("Status Review of the Ribbon Seal (Histriophoca fasciata)", 2008; Fedoseev, 2002; MacDonald and Cook, 2009; Macdonald, 2006)
When ribbon seals feel there may be a threat, they scan the area visually for a much longer period than other pinnipeds. Poor eyesight out of water is believed to be the reason for this extended scanning. When on the ice, they use their fore-flippers to dig in and propel them forward. ("Status Review of the Ribbon Seal (Histriophoca fasciata)", 2008; Macdonald, 2006)
There is little known about home range size in ribbon seals.
Ribbon seals have long vibrissae that are sensitive to vibrations in the water and can be used to locate prey. They have well-developed hearing across a broad range of frequencies in water. It is believed that they use a system similar to echolocation for navigating through water and for catching prey. Ribbon seals also have well-developed auditory senses on land, although their hearing occurs across a narrower range of frequencies than in water. Two types of sounds have been recorded for ribbon seals. These sounds are believed to be used for communication with other ribbon seals, but there have been no studies to confirm this. Other pinnipeds make sounds to communicate during hunting or mating. Little research has been conducted on hearing in ribbon seals, but other pinnipeds have poor hearing in water because they are well adapted to spending large amounts of time on land. The water slows down sound waves, making their hearing poor. ("Status Review of the Ribbon Seal (Histriophoca fasciata)", 2008; Richardson, et al., 1995; Watkins and Ray, 1977)
It is thought that ribbon seals have poor vision on land because of their reactions to potential threats. They look for danger, but they scan the land area for longer periods of time than other pinnipeds. Ribbon seals allow human approach more often than other pinnipeds. They are believed to have well-developed vision in water. ("Status Review of the Ribbon Seal (Histriophoca fasciata)", 2008; Burns, 1970; Richardson, et al., 1995; Watkins and Ray, 1977)
Ribbon seal food habits vary depending on their age, time of year, and location. Stomach contents are different during the spring months, when ribbon seals begin whelping. Females undergo a brief fasting during whelping and lactation in order to provide nutrition and protection to the pup. As juveniles, they feed primarily on shrimp and other small crustaceans. Adults eat different types of cephalopods, crustaceans, and fish. Primary diet components are walleye pollock (Theragra chalcogramma) and magistrate armhook squid (Berryteuthis magister). On average, ribbon seals consume 7.7 kg of food per day. ("Status Review of the Ribbon Seal (Histriophoca fasciata)", 2008; Dehn, et al., 2007; Fedoseev, 2002; Macdonald, 2006)
A common predator of ribbon seals is humans (Homo sapiens). From 1956 to 1992, hunting of several species of seals that lived on ice was a popular sport. This drastically decreased population sizes of ribbon seals. Humans still hunt ribbon seals, but it is not as common as it once was. Polar bears (Ursus maritimus), walruses (Odobenus rosmarus), killer whales (Orcinus orca), and pacific sleeper sharks (Somniosus pacificus) also prey on ribbon seals. Ribbon seals have been found in their stomach contents. Polar bears and killer whales are the most likely predators of ribbon seals. Both share the same habitat as ribbon seals and are known to eat other seals. Killer whales are most likely the major predator because they are found throughout the entire ribbon seal range. The range of polar bears typically does not extend further south than St. Matthew Island, so they are less likely to prey on ribbon seals, especially during the spring months when the ribbon seals migrate south. Ribbon seals typically struggle when they are harassed less and often "play dead" until they are released. ("Status Review of the Ribbon Seal (Histriophoca fasciata)", 2008; Burns, 1970; MacDonald and Cook, 2009; Macdonald, 2006)
Ribbon seals are potential prey for species such as polar bears and killer whales. Other species may use the abandoned ice rookeries of ribbon seals as shelter or for breeding. ("Status Review of the Ribbon Seal (Histriophoca fasciata)", 2008; MacDonald and Cook, 2009)
Ribbon seals do not provide known sources of economic benefit to humans, although sport hunting was common in the past.
There are no known adverse effects ofon humans.
There is little data on the current conservation status of. According to the IUCN Redlist, the most recent population study was conducted in the 1970s. At that time, research suggested that populations were declining. A 1979 study estimated the population size as 450,000 to 500,000 individuals. Since that time, Russia has mostly stopped large scale commercial hunting and, in the United States, they are protected by the Marine Mammal Protection Act. These legislative acts were enacted after the last population study, so it is generally believed that population sizes should have increased. Due to the lack of current data, the IUCN Red List notes the current conservation status as "Data Deficient".
Ben Berry (author), Radford University, Kelsey Townsend (author), Radford University, Christine Small (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
the body of water between Europe, Asia, and North America which occurs mostly north of the Arctic circle.
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.
uses sound to communicate
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
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.
an animal that mainly eats meat
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.
The process by which an animal locates itself with respect to other animals and objects by emitting sound waves and sensing the pattern of the reflected sound waves.
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.
parental care is carried out by females
a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.
Found in northern North America and northern Europe or Asia.
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).
makes seasonal movements between breeding and wintering grounds
eats mollusks, members of Phylum Mollusca
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).
an animal that mainly eats fish
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.
having more than one female as a mate at one time
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
breeding takes place throughout the year
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