The gills of a Pteronarcys (Plecoptera, Pteronarcyidae). Pteronarcys are very sensiti

The gills of a Pteronarcys (Plecoptera, Pteronarcyidae). Pteronarcys are very sensitive to stress, and occur mostly in small-order streams in fast riffles. They also use autohaemorrhaging to ward off predators. Autohaemorrhaging, or reflex bleeding, is when an animal deliberately ejects blood (usually when the blood contains toxic compounds).

Plecoptera, Pteronarcyidae, Pteronarcys. Prince Brook, Oswego County, NY.