Everywhere you look on Earth, you’ll find wonderful and diverse living things, from tiny tardigrades to soaring sequoias. And incredibly, everything alive today, and everything that’s ever lived, is related. In this episode of Crash...

In this episode of Crash Course Biology, we’ll learn about the ways population genetics reveals how groups of living things evolve—by comparing genetic similarities and differences. We’ll discover the most genetically diverse species of...

There’s an immense world of tiny stuff within us and around us—but how do we know about it? In this episode of Crash Course Biology, we’ll discover how we see what we can’t see, thanks to the help of centuries-old tools and more recent...

This is a love letter to water, life’s solvent, and one of the most wonderful molecules around. In this episode of Crash Course Biology, we’ll learn about how water’s polarity and hydrogen bonding help it sustain life on a larger scale....

Despite the diverse appearance and characteristics of organisms on Earth, the chemicals that make up living things are remarkably similar, often identical. In this episode of Crash Course Biology, we’ll look at the building blocks of the...

Crocodiles, and birds, and dinosaurs—oh my! While classifying organisms is nothing new, phylogeny— or, grouping organisms by their evolutionary relationships—is helping us see life in a whole new light. In this episode of Crash Course...

Humans may have been around for a long time, but life has existed for way longer. In this episode of Crash Course Biology, we’ll journey through deep time to uncover the history of life on Earth. We’ll explore the big, game-changing...

How can you tell two species apart? It’s not always simple. In this episode of Crash Course Biology, we’ll learn about speciation—a process that can happen over millions of years, or within a single generation. Along the way, we’ll...

There are lots of ways that evolution happens, and natural selection is just one of them. In this episode of Crash Course Biology, we’ll find out how this process works and shapes traits in all living things —from ginkgo trees to howler...

Whether we’re talking about tigers, trees, or tarantulas, evolution happens at the level of the population. In this episode of Crash Course Biology, we’ll find out how natural selection, gene flow, genetic drift, and other processes...

Life on Earth has weathered boiling-hot oceans and volcanic-ash-darkened skies—but that’s nothing like the climate change we’re experiencing now. In this episode of Crash Course Biology, we’ll talk about the greenhouse effect, learn why...

When the Bald Eagle population started to decline in the mid-20th century, scientists began to ask why. Population ecology, the study of organisms of the same species, played a big role in answering that question. In this episode of...

Ecology is the study of the interactions of living things with each other and their environment. It’s a field that not only lets us explore the interconnections between living things, but also how our environment affects us, and how we...

Here on Earth, life is dizzyingly diverse—but it’s also surprisingly organized. A sense of order structures life and its processes, from the tiniest cell to the total sum of every living thing. In this episode of Crash Course Biology,...

Humans have been transforming seawater into potable freshwater for millennia. Today, billions of people can’t access clean drinking water, and 87 different countries are projected to be “water-scarce” by 2050. So, how can we use seawater...

When reading "Alice's Adventures in Wonderland," most readers visualize the queen’s croquet game play out in their heads. A few might see the scene in vivid detail. However, a small fraction of readers have a drastically different...

Two species of Demodex mites specifically inhabit human follicles. And not just some people’s— nearly everyone is thought to host mites. One person’s face might harbor hundreds or even thousands of individual mites. On any given day,...

For as long as humans have had lice, we’ve fought hard to get rid of them. Nit combs, the fine-tooth brushes used to remove lice and their sticky eggs, have been found among the ancient remains of cultures across the globe. Today it’s...

Electric eels can emit some of the largest shocks in the animal kingdom - but why don't they shock themselves?

It seems wild that some animals basically trade in their bodies for new ones during their lifetime, but it's actually really common – and it makes a lot of sense.

We've long known that animal pollination is an important way plants reproduce on land, but we're only just finding out animals also pollinate plants underwater.

Plants can tell when competitors are nearby because they can see them.

Join the Amoeba Sisters in this longer review video as they review food chains, food webs, how energy flows through trophic levels (including the 10% rule), ecological relationships (including parasitism, mutualism, and commensalism),...

Charles Darwin introduced the notion of “survival of the fittest,” where the fittest animals are those who can survive long enough to produce healthy offspring. The fittest animal can also be the most stealthy, resourceful, or even the...