At the top of our immortal animals list is a tiny variety of jellyfish known as Turritopsis doohmii, or more commonly, the immortal jellyfish.
The 'immortal' jellyfish, Turritopsis dohrnii
To date, there's only one species that has been called 'biologically immortal': the jellyfish Turritopsis dohrnii. These small, transparent animals hang out in oceans around the world and can turn back time by reverting to an earlier stage of their life cycle.
It's a tardigrade—the most 'indestructible' animal on Earth. Also called water bears, tardigrades can survive up to 30 years without food, live in volcanoes, and endure the vacuum of space. Researchers say they could even survive an asteroid impact like the one that led to the extinction of the dinosaurs.
Why tardigrades are so damn tough. It's important to note: Tardigrades are basically indestructible only when they enter a special state called cryptobiosis. In harsh environments, the animals tuck in their legs and expel all moisture from their bodies. In this state, they're called tuns.
Tardigrades belong to an elite category of animals known as extremophiles, or critters that can survive environments that most others can't. For instance, tardigrades can go up to 30 years without food or water.
Tardigrades are among the most resilient animals known, with individual species able to survive extreme conditions – such as exposure to extreme temperatures, extreme pressures (both high and low), air deprivation, radiation, dehydration, and starvation – that would quickly kill most other known forms of life.
Animals with no natural predators are called apex predators, because they sit at the top (or apex) of the food chain. The list is indefinite, but it includes lions, grizzly bears, crocodiles, giant constrictor snakes, wolves, sharks, electric eels, giant jellyfish, killer whales, polar bears, and arguably, humans.
Jellyfish, starfish, and even corals manage very well without hearts. Starfish do not even have blood, so this explains why no heart is required. Instead, they use small hair-like structures called cilia to push seawater through their bodies and they extract oxygen from the water.
The Scoop. The honey badger has been called the world's most fearless animal because it doesn't hesitate to attack animals much larger than itself- even lions and crocodiles! Honey badgers are found in arid grasslands and savannahs and even rainforests.
Rats and house cats were the easiest presumed pushovers, with two-thirds of participants claiming they could see one off, while grizzly bears, elephants and lions were rightfully respected – only 2 per cent of pollsters claimed they would be able to take one down.
Did anyone know that some animals have blue blood, especially when it is exposed to oxygen? Can you guess what animals might have blue blood? Lobsters, crabs, pillbugs, shrimp, octopus, crayfish, scallops, barnacles, snails, small worms (except earthworms), clams, squid, slugs, mussels, horseshoe crabs, most spiders.
Snails have more teeth than any animal.
This is TRUE. A snail's mouth is no larger than the head of a pin, but can have over 25,000 teeth (but these aren't like regular teeth, they are on its tongue).
Spiders usually have eight eyes (some have six or fewer), but few have good eyesight. They rely instead on touch, vibration and taste stimuli to navigate and find their prey.
It is not for nothing that the honey badger has earned the reputation of being the most fearless animal in the world. Despite its small size, this carnivore is known for its ferocious defensive abilities and aggressive nature.
But simians are not alone; crows, elephants and many other creatures are also known to seek revenge.
Butterflies are not even able to defend themselves. The worst they can do is make one of their predators feel ill after it eats a butterfly. Conservationists have stressed that healthy moth and butterfly populations are essential to most ecosystems.
The quokka, a small marsupial native to Australia, is one such example of a species vulnerable to extinction in the country's harsh surroundings. Known as the “happiest animal in the world” due to its cute and friendly appearance, these creatures are now only found in a few isolated forests and small islands.
Rottnest Island is known worldwide to be the home of the happiest animal on Earth – the Quokka (Setonix brachyurus). Close relatives of Wallabies, these tiny animals are found all over Rottnest Island, where their survival is largely attributed to the exclusion of any natural predators.
Sheep, Goat, Cattle and pig were considered relatively gentle. Was this answer helpful?