Horsehair worm in spirit, collected in Scotland, 1905–07

The horsehair worm (Gordius aquaticus) is a species in the phylum Nematomorpha.

Nematomorphs are long thin worm like animals that are parasites in their larval form and free living as adults. They infect certain insects and crustaceans and can be found in marine, freshwater and terrestrial environments.

This specimen was found in Lanarkshire, Scotland and has been preserved in spirit and mounted on white glass.