Animal Behavior – CrashCourse Biology #25

Behavior is action in response to a stimulus. My cat Cameo is now responding to both an external stimulus the sound of a bag of treats, and an internal stimulus her hunger, or at least her insatiable desire for treats. Sometimes animal behavior can seem really far out, but if you look closely enough, you Read more…

What Did the First Animal Look Like?

[ intro ] One of the central concepts in evolutionary theory is common descent, meaning that all living organisms can be traced back to a single common ancestor. In other words, all life on Earth is related. That means, in theory, you could trace your way from child to parent to connect even the most Read more…

Taxonomy: Life’s Filing System – Crash Course Biology #19

Taxonomy! It’s the science of classifying living things. That sounds exciting. Today we’ll basically be learning the Dewey Decimel System of evolution! It’s like filing! You must be on the edge of your seat. OK, shut up. When it comes down to it, this science doesn’t just categorize organisms, when you look a little deeper, Read more…