How does the text define arachnids about tarantula?

The text defines arachnids as a class of joint-legged invertebrates that includes Spiders, scorpions, ticks, and mites. Tarantulas, as a type of spider, are characterized by their eight legs, segmented bodies, and the presence of fangs that can inject venom. Unlike insects, arachnids do not have antennae or wings, and they typically have a more robust body structure. Tarantulas are notable for their size and unique behaviors, distinguishing them within the broader arachnid classification.