With Earth Day coming next week, let’s take a fun look at animals who live not on top of the earth…but inside it.
Mammals, reptiles, insects and many more creatures dig this earth.
Mammals. Many mammals live underground to give birth and raise their young.
Bears come first to mind, as the largest hibernators on our planet. They live roughly half their lives inside their dens.
Badgers, rabbits and foxes occupy dens too.
Many smaller mammals, like this mongoose below, live in burrows. Burrows, like dens, provide protection from predators as well as temperature extremes.
Warthogs, mammals in the pig family, do not have fur and use their burrows to stay warm, give birth and raise their young. They use their ivory tusks to dig for tubers, leaving the burrow-digging to other animals, usually using old aardvark burrows.
In Africa, guides warn you not to stand in front of any holes because it could be a warthog burrow; and those small but ferocious animals come bounding out tusks-first if they sense danger.
You might not guess that river otters use dens. Although they spend a lot of time in the water, they require oxygen to breathe.
Like warthogs and many other mammals, river otters use the burrows of other animals, usually beavers, for giving birth.
While many animals borrow burrows, prairie dogs are the original architects of their underground kingdom.
Found in the grasslands of North America, prairie dogs have short bodies and strong claws perfect for digging. They build extensive underground colonies, called towns, that can span hundreds of acres.
Where I live in Northern California, hibernating chipmunks are starting their springtime surfacing. These adorable little animals are so busy, I love it when they return topside.
This vole had me laughing on a recent day at dusk, as it stealthily scrambled out of his hole, grabbed a morsel from under the bird feeder, then shot back to the burrow. He did this numerous times, one tiny morsel at a time.
Some birds use burrows, too.
Burrowing owls use ground squirrel or prairie dog tunnels for their roosting and nesting.
Kingfishers and bee-eaters also nest underground. Bee-eaters loosen the soil or sand by jabbing with their sharp bills, then use their feet to kick out the loosened debris.
Reptiles. Ectotherms, like lizards and snakes who rely on outside sources for thermoregulation, need the energy of the sun to move. After a winter of hibernating underground, they wake up in spring and come out of the earth.
On warm days lately our western fence lizards and alligator lizards are joining us.
A few years back, we found this California whipsnake, who moves as fast as a whip, foraging on top of the bush because the ground hadn’t warmed up yet that day.
Insects and Others. The world of insects is immense, as you know, but here are a few familiar insects who live inside the earth.
Cicadas come out of their burrows after living underground for years in the larval stage. The underground hibernation can last as long as 17 years for some species.
Beetles often live underground too.
Perhaps the most familiar underground insects to humans are termites and ants.
Termites are colonizing insects, of which there are many kinds. The mound-building termites found in Africa, South America and Australia build above-ground structures that act as ventilation systems for the underground nest. Often the mound outlives the colony.
This is a dormant termite mound in Australia that is over six feet tall. In the background of this harsh and dry habitat you can see smaller mounds across the landscape.
And ants, well they are the most supreme underground beings on this earth. Our planet has tens of thousands of ant species. Highly social insects, they form elaborate organized colonies underground.
Leafcutter ants, my favorite ant species, can be found in tropical parts of the Americas. Next to humans, leafcutter ants form the largest and most complex animal societies on Earth.
In this photo, each ant is carrying a morsel of leaf they have bit off. They are headed, all in the same direction, to their subterranean fungal garden. In just a few years, their nests can grow to 98 feet across (30 m) and contain eight million ants.
Lastly, earthworms, crustaceans and many water-associated creatures also live below earth’s surface. These fiddler crabs were entertaining us during low tide, as they skittered in and out of their burrows.
Underground nests, burrows, and dens benefit the earth in many ways, and they have fascinating creatures to watch.
Whether they come bounding out of their burrow in a deadly pursuit, or languidly emerging after 17 years, underground creatures have elaborate subterranean worlds.
Cheers to Earth Day and all of us who live on and in this planet.
Written by Jet Eliot.
Photos by Athena Alexander.