1. King Cobra
   Green Anaconda
2. Reticulated Python
   Boa Constrictor

the reticulated python, while not as heavy as a green anaconda, does grow to be a longer snake overall. The longest reticulated python currently in captivity is in Kansas City and measures an impressive 25 feet in length. Her name's Medusa!

1. Blue whale
   Sperm Whale
2. Northern Right Whale
   Sei Whale

Blue whales are not just big whales, they're the biggest whales. And not just the biggest whales, they're the biggest animals ever. A full-grown blue whale can hit lengths of nearly 100 feet and the longest on record was 110 feet.

1. Vampire Squid
   Nautilus
2. Lion's Mane Jellyfish
   Manta Ray

You may not have heard of a lion's mane jellyfish before, but they're an extremely impressive animal and possibly the longest thing in the world in a technical sense. While a blue whale has a longer body, the tentacles of the jellyfish can grow to an alleged 196 feet, though such measurements are often estimated.

1. Emerald Boa
   Western Python
2. King Cobra
   Green Anaconda

The green anaconda is the largest snake in the world. The reticulated python may be longer overall, but the anaconda is heavier and its length is nothing to sneeze at. Some have reached measurements of over 26 feet in length.

1. Bootlace Worm
   Bobbit Worm
2. Western Eel
   Rankin's Tube Worm

You may have never seen a bootlace worm in real life and that's just as well. A species of ribbon worm, the bootlace worm lives in the sea and extrudes mucous when threatened. In 1864 one was found that was said to be 180 feet long. Generally, they grow from 16 to 30 feet or so. Either way, at 5 mm thick, that's one long worm.

1. Sting Ray
   Giant Ocean Manta Ray
2. Nautilus
   Sunfish

The giant ocean manta ray is a pretty big beast thanks to that long, whip-like tail that drags behind it. It may not be the longest of all creatures in the world, but with a length of nearly 23 feet, it's pretty impressive nonetheless.

1. Milk Snake
   Coral Snake
2. Black Mamba
   Amethystine Python

The amethystine python, sometimes called the Australian scrub python, is Australia's longest snake. Typical lengths are about 16 feet but some have been said to top 27 feet. It gets its name not from its scales by its eyes which are said to have a milky purple sheen like amethyst.

1. Pickerel
   Beluga Sturgeon
2. Rock Bass
   Sei Salmon

Beluga sturgeon are not actually related to beluga whales in any way. Both names come from the Russian word for "white" which describes the underside of the sturgeon. The largest sturgeon on record was 23 feet 7 inches in length. That's a heck of a fish.

1. Colossal Prawn
   Rock Lobster
2. Japanese Spider Crab
   Horseshoe Crab

Japanese spider crabs don't have the biggest bodies in the world, but they don't need them with those massive legs. In fact, they have the greatest leg span of any creature with an exoskeleton that can reach 18 feet from claw to claw.

1. Honey Fungus
   Sea Sponge
2. Aspergillus
   Death Cap

The honey fungus is a species of parasitic mushroom. There is a specimen of honey fungus in Malheur National Forest in Oregon that is positively massive, covering 3.4 square miles. It's thought to be about 2,400 years old, too.

1. Giant Weta
   Katydid
2. Chan's Megastick
   Horned Beetle

Chan's megastick is one of the longest insects in the world with at least one specimen at the Natural History Museum in London measured 22.3 inches in length. To give that a little perspective, your forearm from elbow to fingertip is probably only about 18 inches or so.

1. African Rock Python
   Pit Viper
2. Brown Taipan
   Black Mamba

The African rock python is the largest snake in all of Africa and can exceed lengths of 20 feet. Thanks to its size it's capable of taking down prey of equally impressive sizes like crocodiles.

1. Thresher Shark
   Killer Whale
2. Great White Shark
   Goblin Shark

No animal in the sea has a reputation like the great white shark, often considered the most dangerous predator in the world even though a lot of that is Hollywood hype thanks to a string of horror movies. A full-grown great white can grow to nearly 23 feet in length.

1. Nile Crocodile
   Gharial
2. Nile Monitor
   Caiman

Gharials are closely related to crocodiles and alligators and are native to India. Unfortunately, the number of gharial left alive in the world is incredibly low, estimated to be under 300 animals in total. Males of the species can grow to nearly 20 feet.

1. Vampire Squid
   Portuguese Man-o-war
2. Colossal Squid
   Giant Siphonophore

Giant siphonophores are very bizarre organisms by human standards. It's not a single organism but a group of smaller organisms each with a different function that come together to form a whole. And they're quite big when they do, coming in at around 160 feet in length.

1. Giant Gippsland Earthworm
   Giant Land Leech
2. Baker's Eel
   Blind Snake

The giant Gippsland earthworm is a massive earthworm found in Australia that typically grows to be over 3 feet long and in some cases will hit over 9 feet in length, which is kind of terrifying for a worm. Word is when they're moving underground it makes an audible sort of sucking sound.

1. Giant Sea Slug
   Bobbit Worm
2. Snake Sea Cucumber
   Silt Eel

The snake sea cucumber is one of the longest sea cucumbers you'll find in the ocean. They grow to around 10 feet in length and sport 15 tentacles that can extend from the cucumber's mouth and allow it to grasp and pull in food.

1. Alligator Gar
   Lamprey
2. Sawtooth Fish
   Oarfish

Oarfish can grow to lengths of 36 feet, making them look very much like long sea snakes. In fact, it's rumored that stories about ancient sea serpents may have been inspired by oarfish which are rarely seen so their appearance would likely be very startling to early sailors.

1. Nautilus
   Giant Octopus
2. Colossal Jellyfish
   Sea Anemone

The giant octopus may not have the size of a giant squid but it's still an impressive beast you probably wouldn't want to run afoul of in the sea. At 11 feet in length and over 150 lbs, this could be a bit of a nightmare in its natural habitat.

1. White Rhino
   Tapir
2. Giant Sloth
   Capybara

Of the two rhino species in the world, the white rhino is the largest with males reaching lengths of nearly 15 feet. The northern white rhinoceros is nearly extinct in the world right now—the last known male died in 2018, though there are still a number of southern white rhinos still alive.

1. Cephalopod
   Blue-Ringed Octopus
2. Giant Squid
   Sea Skate

The giant squid was long considered a creature of legend and it wasn't until 2004 when images of a real one were finally captured. In 2012 a live squid was filmed for the first time.

1. Basking Shark
   Thresher Shark
2. Goblin Shark
   Sand Shark

Basking sharks are filter feeders, meaning they feed on plankton that they suck into their mouths. They can grow to a remarkable size, around 25 feet with some reported as high as 40 feet. Though they're generally passive creatures they are still widely hunted for their fins.

1. Blue Whale
   Sei Whale
2. Northern Right Whale
   Sperm Whale

Sperm whales are one of the larges species of whale in the ocean, reaching lengths of over 65 feet. The whales get their rather awkward name from the oil that the whales used to be hunted for, which was once thought to be sperm.

1. River Monitor
   Caiman
2. Tomistoma
   Tegu

Tomistoma is a member of the same family animals like the crocodile and the alligator. Males can reach lengths of 16 feet or so. As you might expect, you don't want to mess with these creatures either. In 2008, the remains of a fisherman were found inside a female of the species.

1. Largetooth Sawfish
   Hammerhead Shark
2. Marlin
   Greenland Shark

The largetooth sawfish, reaching lengths of around 25 feet, isn't exactly as menacing as it might look. That saw on its face isn't a weapon so much as it's a tool that the fish can use to dig up the soil at the bottom of the sea to hunt for prey.

1. Caiman
   Nile Monitor
2. Komodo Dragon
   Tegu

The Komodo dragon is the largest living species of lizard in the world and can get to about 10 feet in length. For a while there was some debate about whether or not Komodo dragons had a venomous bite or just a mouthful of bacteria, though it's generally accepted now that they do, in fact, have venom.

1. Whale Shark
   Narwhal
2. Sei Whale
   Harbor Porpoise

The largest whale shark ever caught was over 40 feet long. Even the mouth of the whale shark is a dramatic thing. It can reach nearly 5 feet wide and contains up to 350 rows of very small teeth.

1. Forest Worm
   Miller's Centipede
2. Giant African Millipede
   Giant Cicada

Giant African millipedes are not huge, relative to something like a python or a great white shark but compared to most other things that creep on the ground, it's an unsettling size. How big is unsettling for a millipede? About 15 inches.

1. Southern Elephant Seal
   Narwhal
2. Walrus
   Manatee

Southern elephant seals are some very big animals with bull males reaching lengths of nearly 20 feet in some cases. There is also a northern elephant seal species but they are typically smaller overall, perhaps 3 feet shorter in length at their longest.

1. Hercules Beetle
   Rhinoceros Beetle
2. Wallace's Long-Horn Beetle
   Titan Beetle

Wallace's long-horn beetle may not be the biggest beetle out there in terms of body length though, at 3 inches, it's still big for a bug. Toss in those horns though, and this Aussie beetle gets pretty huge.

1. Sei Whale
   Beluga Whale
2. Humpback Whale
   North Pacific Right Whale

The massive North Pacific right whale, capable of reaching lengths of 65 feet or so, has faced a number of threats over the years. Hunting and habitat loss have dropped the whale's wild population down to only a couple hundred.

1. American Alligator
   Saltwater Crocodile
2. Caiman
   Gharial

Saltwater crocodiles are not the sort of animals you ever want to get too close to. Growing up to 20 feet in length, there are up to 200,000 of these creatures in Australia enjoying their lives as apex predators.

1. Sea Anemone
   Sea Slug
2. Giant Barrel Sponge
   Giant Coral Bloom

Giant barrel sponges have a diameter of about 6 feet, which, if you've ever had to buy a kitchen sponge, is pretty big for a sponge. They're also extremely long-lived with some estimated at cracking 2,000 years in age.

1. Portuguese Man O' War
   Vampire Squid
2. Lion's Mane Jellyfish
   Irukandji Jellyfish

The Portuguese man o' war is a fairly unsavory animal to run across if you're a swimmer, thanks to that painful sting. The tentacles can range from 30 feet to over 90 feet in length.

1. Amazonian Giant Centipede
   Giant African Millipede
2. Tomistoma
   Bootlace Worm

The Amazonian giant centipede can grow to be a foot long and possesses an incredibly potent venom. Though not often deadly to humans it is remarkably painful and a single bite could leave you hospitalized for upwards of a week or more.

1. Colossal Squid
   Vampire Squid
2. Nautilus
   Giant Octopus

The colossal squid may grow to 46 feet in length which seems like a good match for those remarkably large eyes. A live specimen may have eyes that are 16 inches in diameter. Hopefully, that means it can see really well.

1. Fluke Worm
   Giant Millipede
2. Bobbit Worm
   Snake Sea Cucumber

The Bobbit worm is a bit of a terrifying predator made all the more frightening by the fact it's so good at hiding. In fact, people have actually discovered these things in their own aquariums after they've hidden away in rocks or coral.

1. Giant Siphonophore
   African Giant Earthworm
2. Chan's Megastick
   Giant Millipede

The African giant earthworm definitely lives up to its name growing to over 4 feet normally and in some extreme cases over 20 feet length. The largest on record was 22 feet. Presumably, no one used it as bait for fishing.

1. Colossal Roundworm
   Giant Flukeworm
2. Whale Tapeworm
   Bobbit Worm

Just about any animal can get a tapeworm in their gut but it makes sense in a way that a whale tapeworm will scale to a whale size. This particular worm is only found in whales that live in Arctic waters and its body can have up to 45,000 segments. Each segment is capable of producing eggs as well.