Is there a chance that more species may actually be closer to fish than we originally thought?

With our current understanding of evolutionary history and our strategy of cladistic naming, if we wanted to have both goldfish and sharks under a single group called "fish", then mammals must also be called...

Paul Andersen discusses the specifics of phylogenetics. The evolutionary relationships of organisms are discovered through both morphological and molecular data. A specific type of phylogenetic tree, the cladogram, is also covered.

There are two classes within subphylum Hexapoda. Those are Entognatha and Ectognatha, or Insecta. The latter will take a while to get through, so let's cover the former first. This one contains springtails, bristletails, and other such...

It took a very long time, but we are finally finished with the clade Protostomia, or first mouths. Now it's time to tackle Deuterostomia, or second mouths, a clade containing only three phyla. This will take some time, since one of those...

We spent a lot of time going through the clade Spiralia, as it contains many phyla, but with that complete it's time to move on to its sister clade, Ecdysozoa, the other large category of protostomes. This clade contains most of all the...

With the marine segmented worms covered, let's get a closer look at Oligochaeta and Hirudinea, which include the familiar earthworms, and the leeches. The anatomy and physiology of the common earthworm is actually quite fascinating,...

“Interpreting a Cladogram” will define and explain how to read a cladogram so that the student can tell how closely living things are related.

Explainer: How bat and pangolin coronaviruses may have recombined to create SARS-CoV-2

Now that we know how to construct cladograms, we have to learn some new terminology. These are the terms monophyly, paraphyly, and polyphyly, and they help us distinguish between any old taxon and true clades. Let's learn more about...

Rotifers exist in a wide range of shapes, from globular, sac-like floaters to elongated worm-like swimmers and creepers to sessile types. In this video we'll focus on the four major clades of this phylum - though there is debate around...

Most of the animals we are familiar with are contained in Nephrozoa, as these are the triploblastic and bilaterally symmetrical animals. The phyla we've covered so far are not part of Nephrozoa, and we have one more to cover before we...

In this video, we explore the fascinating world of mammals. From humans to whales and primates, mammals are a diverse group of organisms with unique characteristics. We delve into their evolutionary history, examining their jaw joint,...

Soon we are going to dive into a study of all the different kinds of animals, but first we need some kind of road map. What are all the major divisions of Kingdom Animalia? Below kingdom is phylum, so how many animal phyla are there, and...

It's time to start digging into Nephrozoa, which is going to take a really, really, really long time to cover. The first major clade within that we will tackle is Spiralia. This includes well-known phyla like Mollusca and Annelida, but...