Today’s Wonder of the Day was inspired by Justin. Justin Wonders, “what is the smallest mammal in the world” Thanks for WONDERing with us, Justin!

Aren't animals cute when they're little babies? Just think about it. Little puppies jumping around with boundless energy…tiny kittens with fuzzy fur…small bunnies with twitching noses…they're all so adorable!

Of course, bunnies, kittens, and puppies usually grow up to be much bigger animals as adults. Are there animals that stay small all their lives? You might be WONDERing what the smallest mammal in the world is.

You'll have to keep your eyes wide open to take in the tiny creatures that vie for the title of Earth's smallest mammal. They're VERY small, but they probably won't replace kittens, puppies, and bunnies on your list of potential pets.

There are actually two mammals that can lay claim to the title of world's smallest mammal. The winner depends upon how you define “smallest." One of the animals weighs the least of any mammal, while the other is the shortest mammal on Earth.

The lightest mammal title goes to the Etruscan shrew (Suncus etruscus), which weighs in at a measly two grams or less. How small is that? It's less than the weight of a dime! Wow! That IS small!

These tiny creatures usually grow to a length of about 2.3 inches or so. Although they're small, they have huge appetites. Etruscan shrews regularly eat twice their own body weight every single day.

The Etruscan shrew is just one of the hundreds of species of shrew that can be found all over the world. The Etruscan shrew is the smallest variety, but all shrews tend to be very small. Some even have venomous saliva that helps them to immobilize their prey to feed their big appetites!

If you're WONDERing why such a small creature has such a big appetite, it probably has something to do with their fast metabolism. Their miniscule hearts beat at a rate of a whopping 25 beats per second. That equals about 1,500 beats per minute. By way of comparison, the average human heart beats at an average rate of 72 beats per minute!

The Etruscan shrew shares the title of world's smallest mammal with a fascinating creature from Thailand: Kitti's hog-nosed bat (Craseonycteris thonglongyai), also known as the bumblebee bat. It gets its nickname from its size — barely over an inch long — which makes it about the size of a large bumblebee!

Thai zoologist Kitti Thonglongya discovered the bumblebee bat in 1973. It gets the “hog-nosed" part of its name from the fact that its nose is pink and shaped like a pig's snout. These tiny bats, while shorter than the Etruscan shrew, generally weigh a little more than two grams.

Bumblebee bats tend to live in groups of 100 or more in the limestone caves of Thailand. They've also been found in Myanmar.

Can you imagine what it would be like to encounter a swarm of these tiny bats? What do you think? Would you want to have either an Etruscan shrew or a bumblebee bat as a pet?

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Tomorrow’s frosty Wonder of the Day might disappear if it gets too warm!