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A guide to aquatic creatures you'll want to meet at the aquarium - Marine mammals edition

Marine mammals are mammals that live in the sea. They include cetaceans, including dolphins, sirenians, such as dugongs, pinnipeds, such as sea lions, and sea otters. They have thick subcutaneous fat, which is mainly used for insulation. We introduce some unique marine mammals that you might want to encounter at the aquarium.

photo: Megumi Seki / text: Masae Wako

Aquatic Creatures Encyclopedia - Marine Mammals Edition
Ringed seal
Baikal seal
walrus
dugong
African manatee
Sea lions
California sea lions
sea otter
beluga whale
Commelin's dolphin
porpoise
Finless porpoise
Killer whale

Ringed seal

The smallest seal with ring-shaped spots

Ringed seal
Order Carnivora, family Phocidae. Also known as the ring seal. Found in the northern part of the Northern Hemisphere. Body length is about 130 cm. In kanji, it is called "ring-patterned seal." What distinguishes it from the spotted seal is the rounded border on the markings on its back. They give birth on drift ice, and the newborn is covered in pure white down.

©Otaru Aquarium

Baikal seal

It is characterized by its large, black eyes. It is a rare marine animal that only lives in freshwater.

Baikal seal
They are of the family Phocidae in the order Carnivora. They live around Lake Baikal in Siberia. They are the only seal in the world that lives exclusively in freshwater. Their eyes have become large so that they can search for prey in the crystal clear waters of Lake Baikal. They are small, measuring 100-140cm in length, but are good at diving. They are carnivorous.

Photo courtesy of Toba Aquarium

walrus

The large fangs are both weapons and tools for drilling holes in ice.

walrus
This is a pinniped of the family Odontoceti, order Carnivora. It lives mainly in areas of pack ice on the continental shelf. Both males and females have well-developed canine teeth (tusks). They use the dense, stiff baleen around their mouths to search for prey in the ocean. They grow to 3-4 meters in length. Their skin is covered with a thick layer of fat.

Photo courtesy of Toba Aquarium

dugong

Only one in captivity in Japan. The model for the mermaid legend!

dugong
They belong to the Dugongidae family of the Sirenia order. They are found in the Indian Ocean and the western Pacific Ocean. They are approximately 3 meters long. Toba Aquarium is the only place in Japan where they are kept and exhibited. Their body has an elephant-like texture and is covered with sensitive sensory hairs. They feed on seaweed that grows on the seabed and have an intestine that is approximately 10 times longer than their body length.

African manatee

A plump sea cow with a cute face from the front!

African manatee
They are part of the Sirenia order, manatee family, and live on the west coast of the African continent. They move between saltwater and freshwater areas. They are about 4.5m long and mainly eat aquatic plants. They have a tail fin that resembles an oar or a rice paddle, and are good at diving. In Japan, only two of them can be seen, at Toba Aquarium.

Photo courtesy of Toba Aquarium

Sea lions

It has leather-like skin and large black fins.

Sea lions
They are part of the Otariidae family of the Carnivora order. They are found in the North Pacific Ocean. They are the largest species of the Otariidae family, with a maximum total length of 330 cm. Adult males have hair growing on the back of their heads that forms a mane. They mainly live in rocky waters, coming ashore on rocky areas to rest during the day. Their name comes from the Ainu word "tonto," which means tanned leather.

©Otaru Aquarium

California sea lions

The champion of the "sea lion show" who excels at agile movements

California sea lions
They belong to the Otariidae family of the Carnivora order. They mainly live in the northeastern Pacific Ocean and the west coast of North America. They are highly athletic and often perform in aquarium shows. They have been kept and exhibited at Ueno Zoo since before the war. Adult males develop a raised lump on their foreheads.

Photo courtesy of Toba Aquarium

sea otter

There are only three endangered species in Japanese aquariums.

sea otter
This species is a member of the Mustelidae family in the Carnivora order. It lives in the northern part of the North Pacific Ocean. Due to its high-quality fur, it has been overfished and is declining worldwide. It eats shellfish by lying on its back on the surface of the water and cracking them open with a stone placed on its stomach. Its body is very dense, with over 100,000 hairs per square centimeter. This helps with buoyancy and insulation.

beluga whale

The "sea canary" with its diverse voices

beluga whale
They are part of the Artiodactyla order and the Narwhal family. They are also known as beluga whales. They live in the Arctic Ocean and the northern Bering Sea. They have a fatty tissue called a melon on their forehead, which they use for echolocation. They make whistling noises. They are 4-5m long and weigh 1-2 tons.

©Port of Nagoya Public Aquarium

Commelin's dolphin

Your eyes will be glued to their lively swimming. Also known as the panda dolphin

Commelin's dolphin
They belong to the Artiodactyla order, Delphinidae family, and are found in the Kerguelen Islands in the southern Indian Ocean. They are one of the smallest dolphins in the world, with a beautiful black and white contrast. They often swim at high speeds and communicate with their companions by rubbing the small protrusions on the front edges of their pectoral fins together. They are approximately 150cm long.

porpoise

A small, rare northern dolphin

porpoise
They are part of the Phocoena family and belong to the Artiodactyla order. They are found in cold coastal areas of the Northern Hemisphere. They are small dolphins, measuring around 1.7m in length. They live near the surface of the ocean and breathe by blowing water, making a sneezing sound. It is rare to see them exhibited together in groups, and Otaru Aquarium is the only one in Japan that does so.

©Otaru Aquarium

Finless porpoise

A type of dolphin with smooth skin and no dorsal fin

Finless porpoise
They belong to the Artiodactyla order and the Porpoise family. They are found along the coasts of China and Japan. They are a familiar marine mammal that also inhabits Tokyo Bay, Nagoya Port, and Osaka Bay. They are approximately 2 meters long and are the only cetacean designated as a natural monument. They are nervous and difficult to train, but their smiling faces are quite memorable.

Photo courtesy of Toba Aquarium

Killer whale

They are easily identified by their white eye patch. They are at the top of the food chain in the ocean.

Killer whale
They are part of the Artiodactyla order and belong to the Delphinidae family. They live in oceans all over the world, including tropical waters. They are 5-7m long and can swim at speeds of over 50km/h. They have white patterns called eye patches above both eyes, which they use to locate each other. They attack in groups and also eat whales.

©Port of Nagoya Public Aquarium

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