AnimalsMammals
The sea otter’s warm secret
No blubber, cold water and the densest fur of any mammal — plus an appetite that shapes a whole forest.
Planet Earth Journal — an independent magazine about animals, remarkable places and the natural world
Mammals
The giants that sing and hunt with bubbles
Humpback whales cross oceans, build nets out of air and sing songs that never stay the same for long.
Amphibians
The salamander that never grows up
Famous in aquariums, rare in the wild: the axolotl keeps its gills for life and can regrow limbs, eyes and even parts of its brain.
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Every story is checked against the sources listed beneath it.
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Deserts
Life at the edge of dryness
Some parts of Chile’s Atacama Desert have not seen rain for centuries. Scientists go there to learn how dry a place can be and still hold life.
Mammals
Seeing the night with sound
Many bats find their way and catch insects in the dark by listening to the echoes of their own calls — most of them too high for us to hear.
Natural phenomenon
The ocean’s own light
Rare on land, common in the sea: in parts of the deep ocean, most animals can make their own light.
Mountains
The mountains that are still rising
The Himalaya were born when India crashed into Asia, tens of millions of years ago. The collision has not stopped.
Insects
The dance that tells bees where to fly
In the dark of the hive, a returning bee dances out a map: the direction of the flowers, and how far away they are.
Birds
How a hummingbird survives the night
By day its heart beats around 1,200 times a minute. On a cold Andean night it can drop to 40 — and its body to just above freezing.
Natural phenomenon
A spark several times hotter than the Sun’s surface
Lightning heats the air to tens of thousands of degrees in a few thousandths of a second. Thunder is the sound of that air exploding outward.
Insects
The butterfly that outlives its parents by months
Several short-lived generations fly north each summer. Then one special generation flies thousands of kilometres south — and lives for months.
At Home
Make big windows visible to birds
Birds can see reflected trees and sky in glass, or see straight through it, and fly into it. Markings on the outside break up the reflection.
How to do itIn Your Garden
Open a hedgehog highway
Hedgehogs roam about 2 km a night looking for food, mates and nesting places. Solid fences and walls block their route.
How to do itOutdoors
Watch wildlife from a distance
Interacting with wild animals can harm both them and you, including through injury and disease.
How to do itFact of the day
No. 01MammalsChecked 5 October 2026
Sea otters have the densest fur of any mammal.
They have no blubber, so this coat is what keeps them warm in cold water. That is also why oil is so dangerous: oiled fur loses its insulating power.
Grow Your Forest
A little curiosity. A growing forest.
Answer five nature questions a day, earn seeds and grow your own digital woodland.
Start today’s challengeAlso new: Wild Numbers, a higher-or-lower game with real numbers from nature.