Definition
Tachypleus is a genus of horseshoe crabs, closely related to *Limulus*. These arthropods are ancient, often called living fossils, with a horseshoe-shaped carapace. They're more closely related to spiders than crabs. *Tachypleus tridentatus*, found in Asian waters, has blue blood used in medical applications. This genus plays a vital role in ecosystems and human health. Think of them as the eastern cousins of *Limulus*! ๐