8 Fascinating Facts about Ribbon Seals

An adult female ribbon seal (Histriophoca fasciata) rests on an ice floe in the Bering Sea. Photo taken from a small UAS during operations to evaluate body condition in ribbon and spotted seals. Credit: NOAA Fisheries/Gavin M Brady. UAS operations are conducted under authority of NMFS Research Permit #23858 and NOAA NIF #N24-17.

1. Ribbon seals are known for their distinctive coat.

This seal gets its name from its distinct pattern of light-colored ribbons around its neck, fore-flippers, and hips. Ribbon seal pups are not born with these distinct ribbons. They develop over a 3-year period with an annual molt (the process of shedding old fur for new fur).

An adult male ribbon seal (Histriophoca fasciata) rests in the sunshine on an ice floe in the Bering Sea. Credit: NOAA Fisheries/Josh M London. Photo taken while working under authority of NMFS Research Permit #23858.

2. These seals move across the ice differently than other ice seals.

Most ice seals move in caterpillar-like undulations across the ice, but not ribbon seals. They propel themselves forward by alternating their fore-flippers and shifting their head and hips in a side-to-side, snake-like motion.

3. Ice floes are important habitats for ribbon seals, which spend most of their time in the open ocean.

These seals haul out on ice floes (a sheet of floating ice) at the edge of the pack ice (dense, drifting mass of ice) in the Bering Sea. They haul out in spring to give birth, nurse pups, and molt. While ribbon seals are closely tied to sea ice for these periods of their lives, they leave the ice once they finish molting.

An adult female ribbon seal (Histriophoca fasciata) looks around among ice floes in the Bering Sea. Credit: NOAA Fisheries/Josh M London. Photo taken while working under authority of NMFS Research Permit #23858.

4. Seal mothers give birth to a single pup.

Ribbon seals give birth during the spring on ice floes in the Bering Sea, and most pups are weaned by mid-May. At birth, ribbon seal pups are approximately 34 inches long and weigh 21 pounds.

A white-coated ribbon seal pup (Histriophoca fasciata) resting on sea ice. Credit: Jessica M Lindsay/NOAA Fisheries. Photo taken while working under authority of NMFS Research Permit #23858.

5. They reach a length of 6 feet and weigh up to a hefty 330 pounds in adulthood.

Ribbon seals are medium-sized when compared to the other three species of ice-associated seals in the North Pacific. They are larger than ringed seals, smaller than bearded seals, and similar in size to spotted seals.

A closeup of an adult male ribbon seal (Histriophoca fasciata) resting on an ice floe. Photo taken while working under authority of NMFS Research Permit #23858. Credit: Jessica M Lindsay/NOAA Fisheries.

6. They live in the North Pacific Ocean and southern parts of the Arctic Ocean.

Ribbon seals are commonly found in the Sea of Okhotsk and Bering Sea. In U.S. waters off Alaska's coast, they can be found in the Bering Sea, and less frequently in the Chukchi and western Beaufort Seas.

The seascape environment in the Bering Sea where we worked was incredible and somewhat otherworldly; we moved through areas like this regularly. Credit: Heather L Ziel/NOAA Fisheries.

7. Ribbon seals have a diverse diet, feeding on a wide range of prey.

They are known to eat fish, squid, and crabs, but detailed information about their feeding behaviors is scarce. Most of the data we have about what they eat is limited to the spring, a time when they generally eat less.

An adult female ribbon seal (Histriophoca fasciata) swims at the surface among ice floes in the Bering Sea. Credit: NOAA Fisheries / Josh M London.

8. Ribbon seals can live up to 30 years.

We don't fully understand the survival and birth rates of ribbon seals. However, the average lifespan of a ribbon seal is likely around 20 years, with a possible maximum of up to 30 years. Ribbon seals reach sexual maturity between 1 and 5 years of age, depending on environmental conditions.

An adult female ribbon seal (Histriophoca fasciata) hauled out on an ice floe in the Bering Sea. Credit: NOAA Fisheries / Josh M London.