Explore the Spanish Series

Logo with the text Biology Crash Course in collaboration with HHMI BiointeractiveHHMI BioInteractive is a proud collaborator on Crash Course Biology and Biología, a new project that reimagines the original Crash Course Biology series that was released in 2012 and makes engaging biology videos available to a wider audience. This new project will consist of two 50-episode series — one in English (Crash Course Biology), and one in Spanish (Crash Course Biología) — covering fundamental topics for general high school and AP-level biology courses.

Through this collaboration, Crash Course Biology and Biología will reflect current priorities in science education while maintaining the levity, humor, and energy that are hallmarks of Crash Course videos. The series will also highlight new scientific advances; emphasize the process of science, including social aspects; and increase access and relevance for all students. 

As part of our commitment to creating more accessible content, the English and Spanish series will be released simultaneously. More than just a direct translation, the Spanish series is adapted from the English series and includes culturally relevant stories and examples presented by a Spanish-speaking scientist. 

What You Can Expect

This page will be the home for Crash Course Biology on BioInteractive. Here, you will find links to all the episodes, which will be released weekly. Most episodes will include links to relevant BioInteractive resources and activities. As always, we look forward to your feedback and ideas for additional resources. 

Image of a man
English Host

Sammy Ramsey

Dr. Sammy Ramsey is an insect researcher, science communicator, and an endowed professor of entomology at the University of Colorado Boulder. His past research has focused on predatory and parasitic insect relationships. As a science communicator, Dr. Sammy uses social media to inspire the next generation of curious minds to fall in love with STEM.
Graphic of a man with biology imagery and the text CC Biology Preview

Preview: Crash Course Biology #00

Welcome to Crash Course Biology! Over the next 50 episodes, we’ll find out how you are connected to every bug, bat, and bacteria that has ever lived. From itty-bitty cells to vast global systems, we’ll see how biology can help us understand ourselves better—and our relationships with the living (and non-living) things all around us. Now I know some of you might be thinking: “Didn’t you already do a Biology series?” Yes, we did. But we’re using everything that we’ve learned over the past decade of Crash Course to make you an even better series. Biology 2.0, if you will. Extra-shiny!

Graphic that has the text 'What is Life?'

Introduction to Biology: Crash Course Biology #01

Biology is the study of life—a four-letter word that connects you to 4 billion years’ worth of family tree. The word “life” can be tricky to define, but a shared set of characteristics helps biologists identify living things. In this episode of Crash Course Biology,  you’ll learn how all of life is connected, and why studying biology can help us better understand ourselves and our relationship to all living things.

Graphic with the text 'The Scientific Method'

The Scientific Method: Crash Course Biology #02

Science offers a way of discovering and understanding the world around us, driven by questions and tested with evidence. And it’s a twisty-turny team effort— you won’t find many lone geniuses out there, or straight lines from hypothesis to conclusion. In this episode of Crash Course Biology, we’ll talk about the big picture of how scientific progress is made, from peer review to mathematical models, with some exploding eggs along the way.

Graphic of two scientists holding a fish with the text "Best job ever"

What Biologists Do: Crash Course Biology #03

A biologist’s natural habitat is anywhere questions about life are being asked—whether the subject is a nematode or a narwhal, a single cell, or a whole ecosystem. In this episode of Crash Course Biology, we’re flipping the microscope around to show how biologists’ work goes down. Along the way, we’ll learn why zebrafish and fruitflies are some of biology’s next top models.

Life's Layers

How Life is Organized: Crash Course Biology #04

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, we’ll uncover the levels of biological organization, discover soil’s superpowers, and find out why the biosphere is kind of like a really, really long train.

Graphic displaying the text 'Solving the mystery'

Why Did All These Elephants Die? (Intro to Ecology): Crash Course Biology #05

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 influence it in turn. In this episode of Crash Course Biology, we’ll get an overview of the field of ecology, see how matter and energy are conserved and transferred through ecosystems, and follow an ecological mystery surrounding the deaths of hundreds of elephants in Botswana, Africa.

Graphic displaying text 'Meet the neighbours'

Community Ecology: Crash Course Biology #06

Community ecology is the study of interactions between different species of living things, and lets ecologists examine the effects of predator-prey relationships, parasites, and mutually beneficial interactions. In this episode of Crash Course Biology, we’ll examine the myriad interspecies interactions with examples, see how keystone species impact their environment and explore how communities rebuild when they are disrupted, through the lens of the 1980 eruption of Mount St. Helens.

Graphic displaying the text 'Saving the bald eagle'

Population Ecology: Crash Course Biology #07

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 Crash Course Biology, we’ll take a look at the methods population ecologists use to study a population and the types of data they collect. We’ll also find out how scientists helped bring the Bald Eagle back from the brink.

Graphic displaying text 'And how we know it's happening

What is Climate Change? : Crash Course Biology #08

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 our climate is like a tangled pair of headphones, and discover that we’ve understood the science behind climate change for much longer than you might think.

Graphic displaying text 'More than polar bears'

The Effects of Climate Change: Crash Course Biology #09

Climate change shakes up all of Earth’s systems, including the living ones. In this episode of Crash Course Biology, we’ll see how climate change’s effects rattle the entire chain of life. Changes felt in one population ripple out to affect entire communities and ecosystems—whether they’re composed of pine trees, puffins, or people.

Graphic displaying text 'Our biosphere'

Conservation Biology: Crash Course Biology #10

Some scientists believe we are in the middle of Earth’s sixth mass extinction: a big, precarious game of Jenga that involves every ecosystem on the planet. In this episode of Crash Course Biology, we’ll see how conservation biology aims to restore habitat and preserve biodiversity. Along the way, we’ll see how environmental damage impacts human communities, and learn about wolves’ return to Yellowstone National Park.

Graphic display text 'too long?'

What a weirdly long giraffe nerve can teach us about evolution.: Crash Course Biology #11

From a single-celled common ancestor, evolution has brought us all of Life’s Greatest Hits — including butterflies, beetles, bacteria, and human beings. In this episode of Crash Course Biology, we’ll learn how evolution explains life’s unity and its diversity. Along the way, we’ll explore the fishy origins of a giraffe’s neck, and find out what a cat’s paw and your own arm have in common.

Graphic displaying the text 'Why some black bears are...white?'

Microevolution: What's An Allele Got to Do With It?: Crash Course Biology #12

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 drive changes in populations. We’ll learn about the Hardy-Weinberg equation, how your alleles make you uniquely you, and how some tigers changed their stripes.

Graphic displaying text 'Survival of the..stickiest?'

Natural Selection: Life's way of Stayin' Alive: Crash Course Biology #13

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 monkeys. We’ll also learn how extra-grippy toes help some lizards survive hurricanes.

Graphic displaying text '99.9% the same'

Why do we have different skin colors? (Population Genetics) : Crash Course Biology #14

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 all (hint: it’s not us), find out why “race” isn’t the biologically valid category we’ve made it out to be, and learn there’s much more in our DNA that we share than that sets us apart.

Graphic displaying text 'horse+zebra=???'

Where Do Species Come From? (Speciation): Crash Course Biology #15

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 discover how a single species can split into two and how a reptile from New Zealand continues to stump scientists.

Grapic displaying text '4.6 billion years ago'

How Did Life Begin?: Evolutionary History: Crash Course Biology #16

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 leaps where life diversified, changed, and just plain persisted.

Graphic displaying text 'More related?'

How We're All Related (Phylogeny): Crash Course Biology #17

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 Biology, we’ll learn why this kingdom-phylum stuff is going out of style and why phylogenetic trees are in.

Graphic displaying text "The biggest family tree ever'

The Tree of Life: Crash Course Biology #18

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 Course Biology, we reveal how the evolutionary relationships between living things define their place on a single, great Tree of Life, and we learn what that tree can tell us about our own place among the planet’s biodiversity.

Graphic displaying text "Nope"

Humans Didn't Evolve From Chimps (Human Evolution): Crash Course Biology #19

What’s a human? And how did we become humans, anyway? In this episode of Crash Course Biology, we’ll meet some of our closest relatives and trace how we evolved into the brainy, inventive, complex species we are today.

Graphic displaying text 'Building blocks of life'

The Tiny Stuff that Makes Big Life: Carbon & Biological Molecules: Crash Course Biology #20

Despite the diverse appearance and characteristics of organisms on Earth, the chemicals that makeup living things are remarkably similar, often identical. In this episode of Crash Course Biology, we’ll look at the building blocks of the four major classes of biomolecules, how those join up to form macromolecules, and how a team of six atoms forms the vast majority of living matter.


A Love Letter to H2O: Water & pH: Crash Course Biology #21

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 helps it sustain life on a larger scale. We’ll see how some water-based solutions can be acidic or basic, and examine how our bodies maintain the narrow pH range necessary for life.

Graphic displaying text 'How do microscopes work?'

How Do Microscopes Work? : Crash Course Biology #22

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 technology. Along the way, we’ll learn about the major types of microscopes and how to use a typical light microscope.