Crustaceans & Molluscs


Crustaceans are a group of animals which have a hard exoskeleton – they include things like crabs, shrimp, and lobsters. Most of them live in aquatic habitats. You are quite unlikely to spot many crustaceans during your walk but keep your eye out for crayfish holes in the river bank. These are most likely made by the signal crayfish which are a non native invasive species which in many places have out competed our native white clawed crayfish.

Another crustacean we have in the River Thame are Freshwater shrimp. They are very common throughout the catchment, although they prefer unpolluted water. They are thought to be beneficial to ecosystems because they eat dead matter from the riverbed.


Molluscs are an extremely diverse group of animals. Slugs and snails are commonly known molluscs but things like mussels and squid are also a part of the group. The most common form of freshwater molluscs are snails. There are a range of molluscs found in the Thame including duck mussels, orb mussels, freshwater limpets, and mud snails.