Welcome to Episode 109! Today's episode is an important one. It marks the beginning of our four part mega series on the arthropods. In this first part, we introduce the most basal arthropod clade, the arachnids, and explore their evolutionary origins. We'll look at the ecological challenges they faced, and the friends and relatives they made along the way. Today's show will set the stage for the rest of the arachnids we'll look at in upcoming episodes, and the rest of the arthropods that we'll explore in the later parts of this mega series.