23 of the biggest living animals in the world

Of the three species of cassowaries found in tropical regions, Australia’s southern cassowary is the biggest, weighing 55 kilos. Although the bird is known for being the second-heaviest bird on Earth, they’re better known for their hot tempers. In an article on Smithsonian.com, it’s said that cassowaries occasionally get into kick fights with inanimate objects.

Saltwater crocodiles can weigh up to 450 kilos and males can measure up to six metres long. The carnivores prowl beneath the water before attacking water buffalos, monkeys and even sharks. In Australia saltwater crocodiles are now a protected species – as are all endemic species – and have gone from being almost extinct in the 1970s to now being widespread in large numbers.

Also known as killer whales, orcas show no mercy to penguins, sea turtles or even sharks when they get hungry. An average-sized orca can eat about 220 kilos of food a day – this is probably why they can weigh up to 5500 kilos. Orcas are the largest dolphins swimming in the freezing waters near the Polar regions and the equator.

One of the best ways to recognise a sperm whale in the ocean is by their massive heads. Although they do have the largest brains of any living thing on Earth, it’s the fact that their heads are filled with spermaceti that makes their biology so fascinating. To this day, scientists only theorise that spermaceti help sperm whales stay buoyant. There has to be something that keeps all 35 tonnes of sperm whales afloat!

It may have a huge brain, but it can’t match the smarts of these 15 animals that are probably smarter than you.

Under the sea, or well under the Pacific Ocean, live a species of crabs much larger than The Little Mermaid’s Sebastian. Japanese spider crabs can grow up to 3.5-metres wide, supporting a body that’s barely longer than 30cm long. Scuttling around with 20 kilos of meat makes this crustacean a dinner favourite in Japan.

Tipping the scale at 4000 kilos, the name of the largest seals in the world comes from their trunk-like snouts rather than their mammoth bodies. Feeding exclusively at sea, it feasts on fish and squid living near the surface of the water as well as those from the deepest, darkest depths of the ocean.

Dalmatian pelicans aren’t your average beach bird. In fact, they’re much larger than average birds because they can grow up to 1.75 metres in height, weigh up to 15 kilos, and can have a wingspan of three metres. Dalmatian pelicans are one of the few birds that can still fly with this much weight.

If Big Bird from Sesame Street had a real-life equivalent, it would definitely be an ostrich. They are the tallest and heaviest birds of all time. Their 150-kilo bodies make them unable to fly, but they can still outrun you at 70 kilometres per hour. Even an ostrich egg is big: they can even weigh up to 1.5 kilos!

While under the sea there are some pretty large animals, the tallest land animal is the giraffe. Full-grown adults can grow up to six metres tall. To get blood pumping from their hearts all the way to the top of their brains, giraffes have a heart that weighs about 12 kilos, while their half-metre-long tongue is used to eat up to 35 kilos of leaves every day from the tallest trees in the African savanna.

Now, this is a fish you probably won’t pick up at the pet store anytime soon, no matter how big your tank is! In the category of fish with bones (sharks have skeletons made up of cartilage, not bones), sunfish are the heaviest of them all, with the heaviest specimen to be weighed to date a whopping 2300 kg. Like sharks, they have a dorsal fin that often gets mistaken for a shark fin when they swim near the top of warm, tropical oceans.