35 of the Biggest Ocean Animals

The oceans hold many mysteries about the beginnings of life on this planet, and its animals have inspired literature, science and art throughout the ages.

Some have only recently been discovered and some have yet to be, but these 35 ocean animals are currently the biggest and boldest the world has to offer.

Whale Shark

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Length: 40-plus feet

Weight: 11 tons

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The largest ocean fish in the world today, there is no known maximum size for whale sharks. They do get plenty of exercise, as they have to travel long distances to find enough plankton to feed on to stay healthy and reproduce.

No one has ever seen them give birth — where and how they do this is still a mystery. They will, however, gather near the surface to feed, which makes this gentle, but endangered, species popular with tourists.

Basking Shark

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Length: 45 feet

Weight: 1,000 pounds

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Basking sharks are the second largest fish in the world. Scientists don’t know much about them, as they do not stay in any location longer than a couple months. They swim the seas with their mouths open in search of their preferred prey, but while they may look menacing, they are harmless.

Basking sharks can pair off or live in large groups of a hundred and live to be about 50 years old.

Blue Whale

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Length: 100 feet

Weight: 200 tons

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While the whale shark is big, it has nothing on the blue whale, which is the largest animal on the planet. To put things in greater perspective, it has the heart of a small car and needs to eat about 6 tons of krill a day to survive. They are also the loudest animals in the ocean and, in the right conditions, can hear each other from a thousand miles away.

Blue whales are listed as endangered, but their populations are increasing once again — pods have recently rediscovered the island of South Georgia in the Antarctic, decades after commercial whaling ceased there.

Fin Whale

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Length: 80 feet

Weight: 80 tons

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The fin whale is the second largest whale and second largest animal on the planet. It is also critically endangered. Nearly 750,000 of them were killed in the Southern Hemisphere in the 20th century, and they are rarely seen there today.

Also called “razorbacks,” fin whales have a distinctive ridge which runs behind their dorsal fin, giving them their name. They dine on krill, small fish and crustaceans and need a lot of them to keep going — they consume over 2 tons a day. Mostly solitary whales, they spend time alone or in pairs and shun the spotlight of the water’s surface.

Giant Manta Ray

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Length: 29 feet

Weight: 5,300 pounds

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The giant manta lives about 40 years in deeper ocean waters than its counterpart, the reef manta. These highly intelligent animals also have the biggest brains of any fish and can even recognize themselves in the mirror.

They are also agile and cunning in the water — they do barrel rolls while feeding to capture the most prey.

Lion’s Mane Jellyfish

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Length: 120 feet

Weight: 200 pounds

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This billowy giant rivals the blue whale in terms of length, and its hair-like tentacles resemble a lion’s mane (hence its name.) It lives in the cool waters of the Arctic and North Pacific, and like other jellies, reproduces asexually and has bioluminescent abilities, meaning it glows in the dark.

Compared to other ocean animals of its size, it has a short lifespan of only one year.

Sperm Whale

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Length: 62 feet (males), 40 feet (females)

Weight: 39 to 53 tons

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The sperm whale is the biggest of the toothed whales and is identified by its massive square head and smaller, narrow jaw. Also called a cachalot, sperm whales live about 60 years and travel the majority of the world’s oceans in pods or individually.

They feed on cephalopods, such as squid and octopuses.

Killer Whale

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Length: 32 feet (males), 28 feet (females)

Weight: 11 tons

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The killer whale is probably the most well known whale to man, with it black and white coloring, patches behind its eyes and countless movies about them — from “Free Willy” to “Orca.” A powerful carnivore, these highly intelligent animals can also recognize themselves in a mirror.

Contrary to popular belief, they don’t live up to their “killer” name — there is no record of this species killing humans in the wild, although it has happened while in captivity.

Great White Shark

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Length: 13 to 20 feet

Weight: 1,200 to 2,400 pounds

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Unlike the killer whale, the great white has taken human lives in the wild and is known to be an aggressive predator. It is the largest predator fish in the world. Fast and extremely muscular, great whites feed on coastal fishes when they’re young and, as they grow, eat bigger marine mammals.

Their run-ins with humans are rare and usually accidental; they take a bite, realize that humans aren’t their desired prey and move on. However, because they are so powerful, this is often fatal to the bite victim.

Oarfish

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Length: 10 feet

Weight: 600 pounds

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Scientists know little about this seldom seen giant that lives in deep ocean waters. Oarfish are perceived as dangerous, but they’re actually docile and shy. They spend their days swimming in a vertical position looking for prey, such as krill, zooplankton, crustaceans, squids, shrimp and jellyfish.

The giant oarfish has a prominent place in Japanese folklore and is known as the “Messenger From the Sea God’s Palace.”

Japanese Spider Crab

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Length: 13 feet

Weight: 40 pounds

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The Japanese spider crab has an extremely long lifespan of 100 years. They look dangerous, but they’re gentle, calm animals that forage for food such as shellfish and dead animals on the ocean floor.

They rarely run into predators, but when they do, they camouflage their shells with kelp to hide. They are largely found in the deep waters of the northern Pacific.

Ocean Sunfish

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Length: 6 feet

Weight: Up to 5,000 pounds

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This species’ scientific name is mola mola. Mola translates to “millstone,” which makes sense because these fish are large, round and grey. They are the heaviest bony fish in the world and live on a diet of various sea creatures, including squid, crustaceans, smaller fish, eelgrass, sponges, jellies and zooplankton.

Mola mola are called sunfish because they lie on their sides basking in the sun at the surface of the water, with the goal of getting seabirds to eat parasites from their skin.

Giant Pacific Octopus

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Length: 16 to 30 feet

Weight: 110 to 600 pounds

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This brightly colored octopus is the largest of the species and makes its home in the northern Pacific. The giant Pacific is highly intelligent and can mimic other species easily.

It lives a relatively short life (about four years), but that’s still longer than your average octopus. It does, however, leave quite a generational legacy — females lay between 18,000 to 74,000 eggs during their lifetime.

Portuguese Man-of-War

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Length: 8 to 165 feet

Weight: N/A

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Often mistaken for a jellyfish, the Portuguese man-of-war is four organisms in one that work together to survive. While it looks like a harmless plastic bag, it delivers a sting that kills its prey. Humans are subject to stings, too, that aren’t fatal but extremely painful.

If you see one, keep a wide berth — their tentacles average 8-feet long but can reach up to 165 feet in some instances. They have no way to propel themselves through the water — they just go with the flow and are found on beaches all over the world.

Giant Sea Star

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Length: 2 feet

Weight: 13 pounds

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Like other sea stars, the giant sea star can regenerate limbs easily if it loses them, which it sometimes does to avoid predators. They live on a diet of barnacles, snails, mussels and limpets by extending their stomachs into cracks in their prey’s shell and digesting the soft tissue inside.

Giant sea stars are found on the Pacific Coast from Southern California to Canada.

Tiger Shark

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Length: 18 feet

Weight: 2,000 pounds

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The tiger shark is the fourth largest shark in the world. Second only to the great white as a predator shark, tiger sharks are bottomless pits and will eat everything they come across — both living and dead sea animals are on the menu, as are inanimate objects, like trash, metal or plastic.

Adults have no known predators. They live in shallow coastal waters, and their bites have been known to be fatal to humans.

Southern Sunfish

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Length: 11 feet

Weight: Up to 5,000 pounds

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The southern sunfish (mola alexandrini) inhabits the southern Pacific Ocean. A bigger relative of the mola mola, it also catches rays on the surface of the water and waits for seabirds to pull parasites from its skin.

This gentle giant feeds on small fish, plankton, mollusks, brittle stars and algae.

Beluga Sturgeon

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Length: 24 feet

Weight: 3,500 pounds

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One of the largest bony fish in the world, the beluga sturgeon begins its life in freshwater rivers, then moves on to saltwater seas as an adult before returning to those rivers to spawn.

The beluga sturgeon can live more than 100 years and reproduce year after year, yet they are critically endangered. This is because they happen to produce the most expensive caviar in the world.

Megamouth Shark

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Length: 16 feet

Weight: 2,700 pounds

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Not much is known about the megamouth shark, as it is rarely seen by humans. It was discovered in 1976, and only 60 have ever been seen or captured. Its mouth is about 4-feet across, hence its name.

It lives on plankton and only comes to the surface at night. In fact, it lives its life in the dark and spends most of its time 15,000 feet below sea level.

Sharptail Mola

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Length: 11 feet

Weight: 4,400 pounds

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Similar to the ocean sunfish and the southern sunfish, the sharptail mola can be found around the world in tropical and temperate ocean waters. Little is known about it, as it is rarely seen and, unlike its closest relatives, does not come up to the surface unless it’s sick or parasite ridden.

This large, bony fish looks like the other sunfish, but with a distinctive convex forehead. Males live to be 85 years old; females outlive them by another 20 years.

Longcomb Sawfish

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Length: 20 to 24 feet

Weight: 4,400 pounds

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Also known as green or narrowsnout sawfish, they are the longest of their species. They feed on fish, crustaceans and mollusks in the subtropical waters of the Indo-West Pacific and are known for their saw-like snout.

Longcombs live about 50 years and are of no threat to humans, although they will protect themselves by thrashing their saw about, which can cause unintentional injury.

Greenland Shark

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Length: 15 to 21 feet

Weight: 800 to 2,100 pounds

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Despite the massive Greenland shark’s size, it is typically wary of confrontation, so much so that it wasn’t captured on film until 1995.

These sharks stay in the darkest depths of the ocean and are some of the longest living vertebrates on the planet — scientists have discovered they may live to be about 400 years old!

Atlantic Blue Marlin

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Length: 16 feet

Weight: 1 ton

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One of the ocean’s strongest predators, the Atlantic blue marlin is sought after by fishermen in its home waters. It is a massive adversary that uses its long bill to stun prey by slashing it and knocking it unconscious.

When it reaches full size, its only predators are sharks. Blue marlins are not hunted for food by humans; however, they are the targets of sport fishermen. Although they are usually released after being caught, they often die after the fact.

Swordfish

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Length: 15 feet

Weight: 1,400 pounds

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The swordfish is one of the world’s largest bony fish that gets its name from the long, sword-like bill that grows from its head. It stuns its prey by slashing them from side to side with its saw and knocking them unconscious.

Swordfish are some of the fastest fish in the ocean, reaching speeds of up to 50 miles per hour.

Smalleye Stingray

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Length: 7.5 feet

Weight: N/A

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The largest stingray in the ocean, the smalleye lives in both the deep waters and shallow reefs of the Indo-Pacific, from Mozambique to northern Australia.

They are shy creatures that are rarely seen by humans — and it wasn’t until 2009 that one was ever captured on film.

Narwhal

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Length: 17 feet

Weight: 4,200 pounds

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The “unicorn of the sea” is one of the most unusual creatures in the world. The tusk jutting from their heads is actually a tooth, and some narwhals may have more than one.

Narwhals inhibit Arctic waters, spending winters in Baffin Bay-Davis Strait, between Canada and western Greenland, where they feed on Greenland halibut, squid and shrimp.

Pacific Halibut

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Length: 9 feet

Weight: 500 pounds

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The largest species of flatfish, the Pacific halibut makes its home in the North Pacific and is a favorite of many sport and commercial fishermen. They are called “barn doors,” due to their massive size.

They can live to be about 55 years old and reside in a broad variety of ocean depths.

Black Marlin

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Length: 15 feet

Weight: 1,000 pounds

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The black marlin is found in both deep and shallow waters of the subtropical Indo-Pacific. The only marlin with non-retractable fins, its massive size makes it a favorite of sport fishermen.

The black marlin feeds on squid, scad, mackerel and tuna and is one of the fastest fish in the world, sometimes reaching speeds of up to 80 miles per hour.

Goliath Grouper

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Length: 8 feet

Weight: 700 pounds

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The Goliath makes its home on coral reefs and mangrove forests in the Atlantic and swallows its prey whole.

They are a critically endangered species, due to destructive fishing practices, and although they are now protected in many countries, theirs is a slow recovery.

Atlantic Bluefin Tuna

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Length: 6 to 10 feet

Weight: 1,500 pounds

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Atlantic bluefin tuna is the largest of its species. This fish is built to move, reaching speeds of up to 45 miles per hour. They prey on herring, mackerel and even eels and hunt by sight, as they have the sharpest vision of any bony fish.

They can live up to 40 years and are the most endangered of the bluefins — their meat is a highly sought-after delicacy in Asian countries. In fact, one fish sold for more than $1.75 million.

Nomura’s Jellyfish

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Length: 7 feet

Weight: 450 pounds

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Nomura’s jellyfish is second to only the lion’s mane jelly in size. They spawn in the seas between Japan and China and have practically invaded the coast of Japan over the last few years.

They release billions of sperm and eggs whenever they feel threatened that attach to rocks and corals and eventually become millions of jellies. They sting humans and prey alike, and their bites have been known to be fatal.

Colossal Squid

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Length: 46 feet

Weight: 1,100 pounds

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Illustration of Colossal Squid with Diver Comparison

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This deep-sea predator has eyes that are bigger than those of whales. Colossal squid live in the waters of Antarctica, and not much is known about them.

They are seen only when captured accidentally by deep-sea fisheries (they sometimes prey on Chilean sea bass caught on lines set by fishermen) and in the stomachs of sperm whales.

Giant Squid

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Length: 16 to 40-plus feet

Weight: 660-plus pounds

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It’s hard to say just how big a giant squid can get — they are rarely seen alive, and almost everything known about them comes from those that have washed up onshore. Scientists believe they can reach lengths of up to 66 feet, but a living specimen of this size has yet to be recorded.

They swim oceans worldwide preying on deep water fishes and other squids, including those of their own kind.

Giant Barrel Sponge

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Length: 6 feet

Weight: N/A

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This large sponge lives on Caribbean coral reefs where its massive bowl-shaped body gives many other invertebrates and fish shelter. The giant barrel lives its life attached to the reef surface and never moves.

It is practically prehistoric — the species has been around for at least 500 million years, and individual sponges can live up to 2,000 years or even longer.

Great Barrier Reef

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Length: 1,429 miles

Weight: N/A

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Corals are animals, not plants, and we’d be remiss to leave out the largest living coral reef system in the world, the Great Barrier Reef. It covers an area of 133,000 square miles located in the Coral Sea near Queensland, Australia.

It’s made up of 3,000 reefs and is so big, it can be seen from space. Within it stands a single coral reef taller than the Empire State building. At 1,600 feet, it may be the largest creature in the world’s oceans.