Ribbon Seal

What is ribbon seal?

The ribbon seal (Histriophoca fasciata) is an earless seal belonging to the family Phocidae, found primarily in the North Pacific and the Bering Sea.¹²

Adult males are distinctively marked with dark brown fur featuring broad, yellowish-white, ribbonlike bands around the neck, front limbs, and posterior body. Females and young seals are generally paler, with less conspicuous markings. Males typically grow to about 1.7 meters (5.6 feet) in length and weigh approximately 95 kg (210 pounds).¹³

These seals are solitary or live in small groups, feeding on fish, squid, and other marine life. While they have historically been valued for their hides by Indigenous peoples and hunted by commercial sealers, their populations are protected by international regulations. As true seals, they are excellent swimmers but move on land by wriggling on their bellies, as they cannot rotate their hind flippers forward.¹³

What is the difference between earless seals and eared seals?

The primary distinction between “eared seals” and “earless seals” lies in their anatomical structure and movement, as both belong to the suborder Pinnipedia but occupy different biological families.⁴

Key Anatomical Differences

• Ears: Eared seals (family Otariidae, which includes sea lions and fur seals) possess visible external ear flaps. In contrast, earless seals (family Phocidae, or “true seals”) lack external flaps and have only small ear holes.⁴
• Flippers and Locomotion: Eared seals have long front flippers and can rotate their hind flippers forward to walk on land. Earless seals have short front flippers, and their hind flippers cannot rotate forward; consequently, they must move on land by flopping on their bellies.⁴
• Swimming Style: When swimming, earless seals propel themselves by moving their hind flippers side-to-side like a fish tail. Eared seals use their long front flippers like oars for propulsion.⁴
• Social Behavior: Eared seals are generally more social and vocal, often communicating through loud barking or bellowing. Earless seals are typically quieter, communicating with soft grunts.⁴

How do ribbon seals survive in the cold waters of the Bering Sea?

Ribbon seals (Histriophoca fasciata) inhabit the frigid waters of the Bering Sea, where they rely on specialized physiological adaptations to maintain their body temperature against the rapid heat-conducting properties of water.¹⁶

Like other marine mammals, ribbon seals utilize a thick layer of blubber—a dense, fat-rich layer of the dermis—to provide essential insulation. Because fat conducts heat poorly, this layer acts as a thermal blanket that prevents the loss of internal body heat to the surrounding environment.⁶

Furthermore, these seals employ countercurrent blood exchange to regulate their temperature. This mechanism allows them to conserve heat by warming cool venous blood returning from the skin’s surface using heat transferred from arterial blood flowing toward the periphery. Conversely, when the animal needs to shed excess heat, it can route blood through superficial veins to release warmth into the environment. These adaptations are critical for survival in environments where water temperatures are significantly lower than the mammal’s core body temperature.⁶

What are some other species of seals found in the Northern Hemisphere?

The Northern Hemisphere is home to a diverse array of seal species, categorized into both earless (family Phocidae) and eared (family Otariidae) seals.

Earless Seals (Family Phocidae)

True seals are particularly abundant in the Northern Hemisphere, with several species inhabiting Arctic and coastal waters:

• Harbour seal: A gregarious, nonmigratory species found throughout the Northern Hemisphere, often seen along coastlines and in some freshwater lakes.⁷
• Harp seal: Known for the large black blotch on their silver-gray fur, these seals are common in northern waters.⁸
• Hooded seal: Found in the North Atlantic and Arctic, males are distinguished by a unique, inflatable nasal appendage.³
• Bearded seal: Named for its bushy whiskers, this Arctic species is known for its rectangular foreflippers.⁹
• Ringed seal: A common, nonmigratory species of North Polar seas, easily identified by the pale rings on its coat.¹⁰
• Baikal seal: A unique, small species found exclusively in Lake Baikal, Russia.⁸

Eared Seals (Family Otariidae)

These seals, which include sea lions and fur seals, are also present in the North Pacific:

• Northern fur seal: Inhabits the North Pacific Ocean.⁸
• Steller sea lion: A large species found in the North Pacific.⁸
• California sea lion: Commonly found along the coasts of the North Pacific ](https://www.britannica.com/animal/sea-lion):** Commonly found along the coasts of the North Pacific.³