8 big beasties from the world’s oceans

The oceans are home to some of the biggest giants to ever grace this earth. With the surrounding water to support them, these colossuses are able to grow to some incredible sizes – some even exceeding the length of a Boeing 737 airplane. 

Here are just some of the biggest, most intriguing beasties living in the deep blue…

#1 Blue Whale

Everyone’s favourite marine giant, the blue whale is the largest animal to have ever lived. Forget the tree-topping Sauropods of the Cretaceous, or the colossal Megalodon sharks that plagued the oceans some two million years ago, this is the winner when it comes to sheer size and bulk. The largest adults can grow up to 98 feet in length and weigh up to a hefty 200 tonnes, their hearts alone the size of a Mini Cooper!



Despite their gigantic size these whales are harmless beasts, choosing to dine on a buffet of tiny crustaceans – up to 40 million per day during bountiful summer feeding seasons. As well as being the largest animal on the planet, they’re also the loudest. The call of a blue whale can reach an ear-busting 188 decibels and can be heard by other whales up to 1,000 miles away. To put those whale moans into perspective, a jet engine only registers at 140 decibels.

#2 Giant Spider Crab

The stuff of nightmares, giant spider crabs – otherwise known as Japanese spider crabs – are some of the largest arthropods in the world, a truly horrifying beastie that you wouldn’t want to dredge up while spending an innocent afternoon crabbing. The largest can grow to a sizeable 20kg, but it’s their leg span that really gets the nerves quivering–adult males boasting an 18-foot leg span.



Living at the bottom of the ocean, these crabs will clamber over one another in giant mounds, transforming into one giant spindly beast quite akin to the aliens from Steven Speilberg’s War of the Worlds.

#3 Sperm Whale

It may not be quite as large as its close cousin – the blue whale – but the sperm whale is still a colossus in its own right. It’s the largest of all the toothed whales, making it the largest toothed predator in the entire world with the biggest exceeding lengths of 67 feet. Perhaps even more impressive, however, is the size of its brain – its huge head housing the largest brain to have ever evolved on planet earth.



Immortalised in the 1851 novel, Moby-Dick, the sperm whale was one of the main targets of the 18thand 19thcentury whaling industry. Targeted for their oil and ambergris, a greasy material from their stomachs used in perfumes, sperm whale carcasses were once a hot commodity all over the world.

#4 Whale Shark

They may be the largest sharks to inhabit our oceans, but their name and size certainly disguise what they really are – full-blown vegetarians. Whale sharks are filter feeders with hundreds of rows of tiny teeth and filter pads which they use to great effect to sift through 1,500 gallons of water an hour, all in search of microscopic plankton to fill their enormous bellies.



An adult whale shark can reach lengths of around 65 feet and amass a weight of up to 12 tonnes, making them the largest fish on the planet. Such a large size makes these sharks quite slow, with many unable to swim at speeds faster than 5 kph – it’s a good job that the microscopic plankton they eat are largely immobile.

#5 Lion’s Mane Jellyfish

Their stings may be as bad as a lion’s bite, but that’s not how these giant jellyfish get their name. Their undersides resemble a giant golden mane, billowing out into the ocean below ready to ensnare any unsuspecting fish or hapless swimmer.

Their tentacles split into eight separate groups, each of which are composed of 70 to 150 strands that can creep their way down to a terrifying 120 feet – longer than both an adult blue whale and Boeing 737 airplane.

#6 Giant Oarfish

Little is known about the giant oarfish, a sinuous, 14-foot sea serpent that lives at the depths of the Pacific Ocean. Of the specimens that have washed up onto popular Californian beaches, scientists have deduced that these creatures are the longest bony fish in the world, reaching lengths of 56 feet and weights of up to 270kg.

Like whale sharks, these beasts are filter feeders that dine on tiny plankton, posing no real threat to humans. Unlike whale sharks however, oarfish are believed to forecast upcoming earthquakes, not only in ancient Japanese mythology, but also by serious scientists.

#7 Giant Squid

The sperm whale’s arch-nemesis, giant squids are the world’s largest known invertebrate – many reaching a length of around 40 feet. These gelatinous giants are very hard to find, with only a few specimens ever recorded.



Marine researchers have found scarring on the bodies of sperm whales which they believe to have been inflicted by giant squid – signs of a vicious rivalry that exists between the two marine animals. Remains of the colossal squids have also been found in the bellies of sperm whales, further evidence that there may be many more of these giant creatures inhabiting the deep ocean. 

#8 Manatee

Perhaps the cutest beastie on this list, manatees are the marine equivalent of cows – large, lumbering creatures that graze on whatever plant matter they can find. Despite their size and bulk, manatees are in fact quite graceful swimmers, able to navigate their forested mangrove swamps and brackish, silty estuarine environments with ease.



They’re naturally curious animals, something that can prove quite detrimental for those populations living alongside humans at the coastline. They can easily become entangled in plastic debris, cut up by boat engines, or even drowned by weighted fishing nets. Such dangers have caused the populations of manatees to dramatically decline over recent years, posing a severe threat of extinction.

To help save the manatees, as well as many of the other animals on this list, head over to 4Ocean and read about all the clean-up events you can get involved with. You can also head to our shop to purchase your very-own Save the Manatees bracelet, each one pulling a pound of plastic from the coastlines that manatees call their home.

Will Newton