Creepy sea spiders have evolved to be tough - Science Magazine

The frigid Antarctic waters pack an especially diverse and vibrant array of sea spiders, marine arthropods that grow as large as dinner plates and use their spindly legs for breathing and digestion.

Researchers fear these critters (like the giant Antarctic sea spider Colossendeis megalonyx, pictured above) could suffer as the oceans become warmer and more acidic, but an international collaboration has shown modern sea spiders come from a long line of staunch survivors.

In the study, scientists genetically sequenced all living sea spider families (spanning 89 species, all distantly related to land spiders) to create the first comprehensive family tree.

The results showed which body parts evolved when, and revealed that the ancestors of modern sea spiders are much older and hardier than previously thought.