What’s the Biggest Sea Creature of All Time?

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Learn all about the blue whale & 10 other massive sea creatures

Co-authored by Samantha Fulton, BA

Last Updated: June 20, 2026 Fact Checked

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The ocean is home to some of the most majestic and mysterious creatures out there, but do you know which ones are the biggest? In this article, we’ll tell you all about the world’s biggest sea creature, the blue whale. Plus, we’ll give you fun facts about 10 other giant sea creatures, in order from largest to smallest (based on weight). Let’s dive in!

The World’s Largest Sea Creatures

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The world’s largest sea creature is the blue whale. However, there are lots of other sizable sea animals. Here are some of the biggest:

• Whale shark (biggest shark)
• Southern elephant seal (biggest seal)
• Great white shark (biggest predatory fish)
• Giant manta ray (biggest ray)
• Leatherback sea turtle (biggest turtle)

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Section 1 of 2:

What is the biggest sea creature?

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   The blue whale is the biggest sea creature by far. Not only are these majestic creatures the biggest sea creature, they’re the largest animal ever known to have lived on Earth! Blue whales can get up to 100 feet (30.48 meters) long and over 200 tons. Their tongue alone can weigh as much as an elephant.
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   Blue whales almost exclusively eat tiny shrimp-like animals called krill. You’d think they’d consume bigger prey to reach their insane size! During certain times of year, an adult blue whale consumes 4 tons of krill per day.
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   Blue whales live in oceans around the world, except for the Arctic. Sometimes they travel in pods, but they can usually be found alone or in pairs. They’re also among the loudest animals on the planet and can hear each other up to 1000 miles (1609.3 km) away.
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   Blue whales have an average lifespan of 80 to 90 years. The oldest one ever found was estimated to be 110 years old! This lifespan places blue whales among the longest-lived animals on Earth. Scientists find the age of blue whales by counting layers of deceased whales’ wax-like earplugs.

   • Blue whales are currently endangered. To help protect blue whales, you can donate your time/money to organizations like the World Wildlife Fund, contact your local representatives about conservation policies, and do your part to create a cleaner environment.
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   There are plenty of other giant whales in the sea! While the blue whale takes the cake for the biggest sea creature, some of the other largest animals in the ocean are more types of whales. We’ll tell you about other giant sea creatures outside of the whale family in the next section, but here are some of the largest whales in the ocean:

   • Fin Whale: 90 feet (27.43 m), 80 tons
   • Sperm Whale: 60 feet (18.3 m), up to 45 tons
   • North Atlantic Right Whale: 60 feet (18.3 m), up to 70 tons
   • Bowhead Whale: 59 feet (17.98 m), 75-100 tons
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Section 2 of 2:

10 Other Giant Sea Creatures

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   Whale Shark The whale shark is the largest shark and largest fish in the ocean. They are found in all the tropical oceans in the world. These big sharks feed on plankton and travel far and wide to find food to sustain themselves. They have distinct white spots that make them easy to identify in the wild.

   • Average length: Up to 60 feet (18.3 m)
   • Average weight: About 11 tons
   • Conservation status: Endangered
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   Basking Shark The basking shark is the second-largest shark and fish in the ocean. Like the whale shark, they love to feast on plankton and are highly migratory. Basking sharks can be found worldwide in cold or warm seas. They have a huge mouth and gills that almost encircle their entire heads.

   • Average length: 22-29 feet (6.7-8.8 meters)
   • Average weight: 5 tons
   • Conservation status: Vulnerable
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   Southern Elephant Seal Southern elephant seals are the largest seals on the planet and the largest mammals after whales. They can be found primarily in the Southern Ocean. Southern elephant seals enjoy a diet of squid, octopus, fish, and marine mollusks. They are highly social on land and gather in massive breeding colonies. However, they are more solitary during their time out at sea.

   • Average length: Female – 8.5 to 9.8 feet (2.6 to 3 meters); Male – 14 to 19 feet (4.2 to 5.8 meters)
   • Average weight: Female – 880-1980 pounds (400-900 kg); Male – 4900-8800 pounds (2200-4000 kg)
   • Conservation status: Least concern
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   Great White Shark The great white shark is the largest known predatory fish. They have 300 teeth, but they actually don’t chew their food… they swallow their prey whole! Great white sharks love to chow down on a range of other animals, from small fish to large seals and dolphins. They sit at the top of the marine food chain and can switch from a steady cruise to high-speed bursts in pursuit of their prey.

   • Average length: 16-20 feet (4.88-6.09 m)
   • Average weight: 4000-7000 pounds (1814.37-3175.15 kg)
   • Conservation status: Vulnerable
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   Giant Manta Ray The giant manta ray is the world’s largest ray. They are found worldwide in tropical, subtropical, and temperate bodies of water. They are filter feeders and consume large amounts of zooplankton. Giant manta rays are a migratory species and make regular visits to coastlines. They’re usually solitary, but they can be seen in groups at cleaning sites or to feed and mate.

   • Average length: Wingspan up to 26 feet (7.92 m)
   • Average weight: Up to 5300 pounds (2404.04 kg)
   • Conservation status: Endangered
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   Leatherback Sea Turtle Leatherback sea turtles are the largest turtle species in the world. They are highly migratory and cross both the Atlantic and Pacific Oceans. Every summer and fall, these turtles migrate from the Coral Triangle to the California coast to feed on the jellyfish. Leatherback sea turtles are solitary creatures. They are named for their shells, which are leathery, rather than hard.

   • Average length: 53-63 inches (1.35-1.6 m)
   • Average weight: 600-1500 pounds (272.16-680.39 kg)
   • Conservation status: Vulnerable
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   Colossal Squid The colossal squid is the largest known invertebrate. This squid is elusive and very rarely found. It lives in the deep waters of the Southern Ocean, around Antarctica. Its eyes can reach diameters of about 12 inches, allowing it to see its prey in the darkness of the deep sea. Sadly, scientists don’t know much about the behavior of these squids—they’ve really got their cool and mysterious aura down pat.

   • Average length: 33 feet (10 meters)
   • Average weight: 1100 pounds (500 kg)
   • Conservation status: Least concern
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   Lion’s Mane Jellyfish The lion’s mane jellyfish is the largest jellyfish species in the ocean. Their long tentacles resemble, as the name implies, the mane of a lion. But that’s not all—these tentacles have neurotoxins that can affect respiratory function when they come in contact with humans. However, the lion’s mane jellyfish tends to hang out in the open ocean, so you shouldn’t run into any on your next beach vacation.

   • Average length: 120 feet (36.5 meters)
   • Average weight: 450 pounds (204.12 kg)
   • Conservation status: N/A
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   Oarfish The oarfish is the longest of all the bony fish. They can grow to over 30 feet long! They are also, and rather ominously, known as the Doomsday Fish. These fish are deep-sea dwellers, which makes them fairly elusive to humans. They are filter feeders that mainly feast on krill, plankton, and small crustaceans. They float vertically in the deep waters of the mesopelagic zone, which allows them to camouflage because of their reflective bodies.

   • Average length: 10-15 feet (3.05-4.57 m)
   • Average weight: 200 pounds (90.72 kg)
   • Conservation status: Least concern
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    Giant Pacific Octopus The giant Pacific octopus grows the largest of all the octopus species. They live throughout the temperate waters of the Pacific, reaching from southern California to Alaska and west to Japan. These are highly intelligent creatures and are even able to open jars and mimic other octopuses! They mainly eat shrimp, clams, lobsters, and fish.

    • Average length: Up to 16 feet (4.88 m)
    • Average weight: 22 to 110 pounds (9.98-49.9 kg)
    • Conservation status: N/A
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