Reindeer live in and around the Arctic Circle, where the winter temperature reaches a chilly -70˚C (-94˚F). In order to survive, fur covers their entire bodies except for one part.

What is the only external part of a reindeer not covered in fur?

The Himalayan jumping spider can survive at elevations of 6,700m (22,000ft) and might be the highest living creature on Earth.

But what does its species name – Euophrys omnisuperstes – mean?

The Dragon's Breath Cave in Namibia's Kalahari Desert contains the largest underground lake in the world that is not under a glacier. One of the world's rarest creatures is found only there.

But what type of animal is it?

One of the hardiest creatures in the world is the tardigrade – a microscopic organism that has been around for approximately half a billion years!

They have many nicknames – but which one of these is the taligrade commonly known as?

In Alaska, the incredible wood frog survives the harsh winter by allowing itself to be frozen solid. Then in the spring, it defrosts and happily hops away.

How long can this incredible frog survive frozen in the tundra?

The giant Greenland shark is thought to have the longest known lifespan of any vertebrate species on the planet.

But what age can it get up to?

Russia's iconic Siberian tiger can survive temperatures as low -43°C (-47°F) thanks to its extra thick fur. This mysterious animal has almost mythic status.

But which country made the Siberian tiger its national animal?

The amazingly adaptive leatherback sea turtle is the largest turtle in the world and can be found in practically every ocean on the planet. It's also quite speedy when it wants to be.

But how fast can it swim?

The Mariana Trench in the western Pacific Ocean is the deepest trench in the world.

One creature was spotted at a depth of 8,178m (26,831ft) – but what was it?

Volcanoes aren't a great place to live. They're incredibly hot, spew noxious fumes and are liable to erupt at any moment.

But one surprising creature has decided to make Nicaragua's Masaya Volcano its home – which one?

The hypersalinity and high alkalinity of California's Mono Lake means no fish can live there.

But the Mono Lake brine shrimp thrives – how many are estimated to live there during the warm summer months?