ANIMALS are known to excrete ammonia, urea, or uric acid as end-products of protein metabolism. So far as we can ascertain, the problem of nitrogenous excretion in arachnids needs more investigation.

Spiders, whose ancestors antedated the dinosaurs, have lived on the earth for millions of years. During that time they have picked up a few tricks besides the fly-catching web. There are spiders ...

Despite their name, horseshoe crabs—bizarre, ancient aquatic critters—don’t look like horseshoes and they’re definitely not crabs. They’re arachnids. Just like spiders, scorpions ...