Heidi Fuchs, a marine biologist at Rutgers University in New Jersey, says she was studying the changing distributions of two species of snails on the east coast of the United States when she realized they had shifted into shallower water.

This migration is baffling because shallow water is often warmer, and warmer water can be lethal for these invertebrates. If they’d simply stayed put, the cooler water offshore should have provided a refuge from temperature increases. Working to figure out what was going on, Fuchs found that while the snails’ spawning habits are changing because of climate change, their adaptations are actually making things worse.