American Oceans

Top 10 Biggest Sea Creatures

The ocean is mysterious; less than ten percent of the global ocean is mapped using modern sonar technology.

a person snorkeling with a whale shark

What we know is that some of the largest animals in the world live in oceans around the globe.

If you’re curious about the biggest sea creatures, you’re in the right place. Let’s dive into the fascinating world of life under the sea.

Blue Whale

a blue whale swimming beneath the surface of the water

Scientific name: Balaenoptera musculus
Family: Rorquals
Length: 80 to 90 feet long
Distribution: All oceans except the Arctic

Blue whales are the biggest animals on Earth. It’s difficult to envision the unbelievable size of this creature but to put it in perspective; their bodies are roughly the size of three school buses.

The largest blue whale recorded was a whopping 110 feet and 17 inches long.

These giant beings have long bodies and are generally slender. They have a mottled bluish-gray color, hence their name. They’ve been found in nearly every ocean except for the Arctic Ocean.

Although they may be scary to look at, blue whales aren’t a threat to humans. Instead, these gentle giants feed on krill or small shrimp-like animals in the ocean.

Lion’s Mane Jellyfish

biggest lion’s mane jellyfish sting in tentacles

Scientific name: Cyanea capillata
Family: Cyaneidae
Length: 120 feet from the top to the bottom of its tentacles
Distribution: Arctic and North Pacific Ocean from Alaska to Washington

The Lion’s Mane Jellyfish has tentacles up to 120 feet long, longer than the length of the blue whale.

They have a translucent reddish-brown body with roughly 1,200 brownish tentacles divided into 8 clusters.

Each tentacle is loaded with poison they use to stun prey. They use these powerful stings to capture small fish, crustaceans, and sometimes other jellyfish to feed on.

In cool waters, you can find this enormous creature in the Arctic and North Pacific Ocean, ranging from Alaska to Washington.

Sperm Whale

Sperm whale in Indian ocean

Scientific name: Physeter macrocephalus
Family: Physeteridae
Length: 40-60 feet
Distribution: All deep oceans, from the equator to the edge of the pack ice in the Arctic and Antarctic

Sperm whales are dark gray, with some having white patches on their bellies. They’re the only living cetacean with a single blowhole sitting on the left side of their head.

Found in all deep oceans, hot and cold, sperm whales have one of the widest distributions of marine animal species.

They’re the largest-toothed whale species. Large males may reach over 60 feet, while females reach roughly 40 feet.

Spending their time deep in the ocean, they feed on squid and shark species and other fish swimming in the ocean depths.

Humpback Whale

Young Humpback Whale

Scientific name: Megaptera novaeangliae
Family: Balaenopteridae
Length: 43-52 feet
Distribution: Throughout all major oceans

The humpback whale gets its name from the distinctive hump on its back. They have dark gray or black bodies with white patches on their bellies, pectoral fins, and underneath their tail flukes.

Humpback whales live across the world’s major oceans and can travel considerable distances during the migration season. The largest humpback whale was 89 feet long and weighed 90 tons.

During warmer seasons, humpback whales spend time feeding to build up fat stores that will last them through the winter.

They filter-feed on small fish and small crustaceans, like krill. 

Whale Shark

Whale Sharks gentle harmless giants

Scientific name: Rhincodon typus
Family: Rhincodontidae
Length: 18-33 feet
Distribution: All tropical and warm temperate seas, except in the Mediterranean

These distinctive sharks get their name from their massive size. However, they’re not whales but the world’s largest fish, growing up to 39 feet long.

Despite their large size, many know them as gentle giants.

They’re not aggressive and aren’t a threat to humans. Instead, they filter feed on smaller plants and animals or plankton.

Whale sharks are gray, blue, or brown with pale yellow stripes and spots and white bellies. Each whale shark has a unique marking, making it easier for scientists to track their migration patterns throughout tropical ocean waters.

Basking Shark

basking shark black brown blue top color appearance

Scientific name: Cetorhinus maximus
Family: Cetorhinidae
Length: 20-26 feet
Distribution: throughout the North and South Atlantic Ocean, the Mediterranean Sea, the North and South Pacific Ocean, the Sea of Japan, off Southern Australia, and around New Zealand

Basking sharks are slow-moving migratory sharks. They’re the second largest fish, reaching up to 50 feet long and over 5 tons.

These sharks are grayish-brown and have a mottled appearance.

Like other sharks, these fish are planktonic feeders; they swim with their mouths open and filter small crustaceans and plankton with their tightly set gill rakers.

You can find basking sharks throughout the world’s temperate and arctic waters. 

Giant Squid

Scientific name: Architeuthis
Family: Architeuthidae
Length: 33-43 feet 
Distribution: The exact distribution is unknown, though giant squids have washed up on shores across oceans worldwide

Aptly named, the largest giant squid scientists recorded was nearly 43 feet long and possibly weighed close to a ton.

Although these animals are large, they live deep in the ocean and are rarely seen.

What we know if this creature comes from the dead carcasses fisherman find once their bodies float to the surface.

Their distribution is unknown, but based on their findings, it seems they live in oceans worldwide.

Although nobody has witnessed a giant squid feeding, they’ve cut open deceased squids’ stomachs to get an idea of their feeding. They eat primarily deep-water fish, including other giant squids.


Scientific name: Regalecidae
Family: Regalecidae
Length: 10-36 feet
Distribution: Worldwide

Oarfish are found worldwide and feature long tapering bodies with small protruding mouths and no visible teeth.

Their dorsal fin is directly above their small eyes and runs the length of the entire body.

The longest oarfish is reported to be 36 feet long, though it’s more commonly seen at lengths of roughly 10 feet in length.

These distinctive fish feed on crustaceans, plankton, and squid, using gill rakes to strain them from the water.

Japanese Spider Crab

spider crab

Scientific name: Macrocheira kaempferi
Family: Inachidae
Length: 12 feet
Distribution: Japan’s Pacific coast

Japanese spider crabs get their name from their unique spider-like bodies. Plus, they’re native to Japan’s Pacific coast.

They’re the world’s widest crustacean, with leg spans reaching 12 feet long.

This slow-moving crab spends its time on the seafloor prowling for food. They scavenge for dead or decaying matter like fish, invertebrates, and algae.

Ocean Sunfish

a diver swimming alongside a mola mola sunfish

Scientific name: Mola mola
Family: Molas
Length: 5 ft 11 in
Distribution: Temperate and tropical waters of every ocean worldwide

The ocean sunfish, or mola mola, looks like a science experiment gone wrong. They’re huge and flat silver fish with tiny mouths and large eyes.

It’s the heaviest bony fish in the world, reaching up to 5,000 pounds.

Although not as big as a shark, they reach nearly six feet long, with the largest ocean sunfish weighing 6,000 pounds.

They eat various foods, though their favorite is jellyfish. They’re native to temperate and tropical waters worldwide.

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