Top 10 Largest Sea Creatures On Earth Today
Top 10 Largest Sea Creatures On Earth Today

Top 10 Largest Sea Creatures On Earth Today

VOICE OVER: Rebecca Brayton
Who's up for a swim in the ocean? For this list, we're looking at the biggest sea creatures living today – so there won't be any aquatic dinosaurs to see. Our countdown includes Great White Shark, Saltwater Crocodile, Giant Pacific Octopus, and more!

Top 10 Most Insanely Colossal Sea Creatures

Welcome to WatchMojo and today we’ll be counting down our picks for the top 10 most insanely colossal sea creatures.

For this list, we’re looking at the biggest sea creatures living today – so there won’t be any aquatic dinosaurs to see.

Let us know in the comments which one you think is the king of the deepsea.

#10: Great White Shark

Many of the ocean’s largest creatures are filter feeders, but that’s not true for the great white shark, which is the largest predatory shark in the entire world. Believed to have descended from the largest shark that ever existed, the Megalodon, great white sharks are thought to be very similar, aside from their smaller size. Great whites are certainly not tiny, though, with many females – which are larger – clocking in at lengths of up to 20 feet and weighing as much as 5,000 pounds. Despite their fearsome reputation, the vast majority of these sharks have no interest in eating or attacking humans, with very few isolated cases being recorded each year. They also have quite the lengthy lifespan, sometimes exceeding seventy years old.

#9: Japanese Spider Crab

It’s not as big as many other creatures on our list, but it’s guaranteed to send a chill down your spine. The Japanese spider crab is a deep-sea dwelling crustacean that truly lives up to its name: though it’s certainly a crab, it has the long, thin limbs you’d usually associate with a spider. In fact, from claw to claw, it can measure between 12-15 feet on average, giving it the longest leg-span of any crab in the ocean. If spider crabs freak you out, the good news is you don’t have to worry about running into one! They live so deep that only fishing trawlers encounter them since they’re often eaten in Japan – however, there are also many people out there fighting for their conservation.

#8: Saltwater Crocodile

Though you generally imagine crocodiles living in swamps and rivers, saltwater crocodiles will also live in the ocean’s coastal regions. They’re also the biggest reptiles in the world, with the biggest weighing close to 3000 pounds and getting to be about 20 feet long. These crocodiles are found throughout the seas of northern Australia, Indonesia, and other parts of South Asia. Frighteningly, these formidable reptiles will attack any potential prey that gets too close – including humans. (Hey, we’re not judging. We get hangry too, sometimes!) They’re as big and widespread as they are aggressive, so if you’re ever in this crocodile’s territory, you’d better get out of there before you… croc.

#7: Lion’s Mane Jellyfish

The monstrous lion’s mane jellyfish is an absurdly large sea creature, with the largest-ever recorded specimen’s tentacles measuring 120 feet! Of the larger jellyfish, the bell itself is also huge, with the largest diameter observed found to be 7 feet! Even the smaller of the species are still pretty big, with a bell of about 20 inches -- and that’s just the bell! It’s not just the size you need to be wary of. They also happen to have a very powerful sting, with tentacles that stun prey. Tentacles, by the way, that come in the hundreds! Thankfully, if you do have an encounter with one of these creatures, you probably won’t require medical attention. And unlike other jellyfish, you’ll definitely see this one coming!

#6: Leatherback Turtle

You’re probably used to the small, friendly turtles people sometimes keep as pets – but those have got nothing on the leatherback turtle, which is the biggest sea turtle in the world. They’re found in the Atlantic and Pacific oceans, and along their coasts -- anywhere from Washington to Costa Rica, to Quebec to Gabon. They’re only about four to seven feet long at most, which makes them pretty comparable to the size of humans. Here’s the catch: they can easily surpass 1000 pounds, which is significantly heavier than most humans. The leatherback turtle dives to astonishing depths and feeds on jellyfish. Whether they’re getting a jellyfish or a plastic bag is usually a coin toss, though, which puts these poor guys at risk for extinction.

#5: Giant Squid

Along with the colossal squid, this is one of the most elusive sea creatures out there. For centuries, we only had washed up squid corpses and the strange stories of sailors to tell us that the giant squid does, in fact, exist. It was as recently as this century that the first underwater photos of the giant squid were taken, in their natural habitat: some of the ocean’s deepest points. We still have a lot to learn about this species, but they certainly live up to their name. The longest of them have reached approximately forty feet in total length, but it’s believed that they could attain up to 66 feet! The squid’s other claim to fame is its eyes: one of the biggest in the animal kingdom, at around 11 inches across.

#4: Whale Shark

There’s plenty of fish in the sea, but this is the largest of the species. Don’t worry! Whale sharks are far from the legendary human-eaters we usually think of. They’re yet another exceptionally large filter feeder, subsisting primarily on a diet of plankton and small fish. They grow to a frankly ridiculous size, with females getting to 48 feet on average. Some whale sharks, however, far exceed this, and might even reach upwards of 70 feet long! Plus, their mouths alone can stretch to be over 4 feet wide. They’re extremely heavy too, with their weight likely averaging around a whopping 40,000 pounds. Their lifespan also rivals that of ours. In some cases, whale sharks might live as long as 150 years!

#3: Giant Manta Ray

The ocean’s largest rays, giant manta rays, commonly get to a wingspan of up to 29 feet wide and weigh over 5,000 pounds. It’s not just the ray’s body that’s huge, though; it also has an extraordinary brain-to-mass ratio, making it an exceptionally intelligent animal. The rays can often be seen at shallow depths, especially when feeding, though they’re able to dive far deeper. They’re also completely harmless to humans, despite their similarities to stingrays (which can certainly pose a threat to humans!). Manta rays are gentle giants of the sea, and seeing them up close is likely a privilege few would pass up. But like many marine animals, they’ve been sadly fished to the point of endangerment.

#2: Giant Pacific Octopus

Octopuses have long been known to be some of the world’s smartest creatures, and the giant Pacific octopus is no exception, with the ability to recognize people, solve puzzles, and mimic other species. They’re so smart, in fact, that keeping them in an aquarium is notoriously difficult; they’re genius escape artists. Generally, adults can be somewhere around 16 feet across, though they’re far lighter than many of the other large animals in the sea, weighing in at only 110 pounds. While those are the average numbers, larger giant Pacific octopuses have also been reported -- the biggest being 600 pounds! Sadly, they have extremely short lifespans by our standards – living only between 3 to 5 years, despite their impressive size and brainpower.

Before we unveil our top pick, here are a few Honorable Mentions:

Giant Oarfish
This Bizarre Fish Can Reach Lengths of Over 26 Feet

Sperm Whale
The Largest Toothed Whale in the Ocean!

Killer Whale
The World’s Largest Species of Dolphin!

Sunflower Sea Star
These Huge Starfish Reach Over 3 Feet from One Arm to the Other

Southern Elephant Seal
The Largest Non-Cetacean Marine Mammal!

#1: Blue Whale

Not only is the blue whale the largest animal living on Earth today, but it’s the largest animal ever known to have lived on Earth in its entire history! Despite their incredible size, blue whales are filter feeders that can’t swallow anything larger than a grapefruit. They’re known for their calling songs, which are divided into at least nine different types. Unlike other whales, they live solitary lives, which is a good thing! Even the ocean might not be big enough for huge groups of blue whales together at once, since they have hearts the size of small vehicles, and can possibly reach up to 110 feet in length. That’s about the height of a ten-storey building!
Basking sharks are big