The Eurypterida (Sea Scorpions)

Eurypterids were a dominant group of aquatic chelicerates, related to scorpions, spiders, and horseshoe crabs. They’re commonly called “sea scorpions” due to a long-recognised superficial similarity to scorpions, as can be seen above. This has led to several studies stating that eurypterids are scorpions (Versluys & Demoll, 1920), that scorpions …

Spider Vision

This is a requested post on the basics of spider eyes; for more on spiders, check out my spider lecture. Spiders only have ocelli, simple eyes consisting of a lens covering a vitreous fluid-filled pit with a retina (pigment cells + visual cells) at the bottom. The ocelli come in …

Spiders

These are slides from a basic public talk I gave on spiders. It’s not zoology course-level, but good if you know nothing about spiders. PDF version. On the arthropod tree of life, spiders are just one group within the Chelicerata, a group of animals characterised by the possession of a …

Pholcids

When I was living in Germany, my room was in the cellar/basement of a house. The most abundant macroscopic organisms in my room are the subject of this post: pholcids. Anyone who has a dusty, somewhat dark room (e.g. a basement, or a cave) will recognise them: they’re the spiders …