What a fun discovery - and a great eye for finding and appreciating the smaller animal life in the lake! This is a freshwater scud (sometimes called ‘sideswimmers’) which is an aquatic amphipod.

Amphipods represent a large order (or group) of small crustaceans, which characteristically have exoskeletons (outer shells or external ‘skeletons’) and are closely related to shrimp and crayfish, crabs and lobsters. Part of a functioning lake ecosystem, scuds are detritivores feeding on dead organic material playing a role of shredding or breaking down organic matter (like leaves) in rivers and lakes. They are also a very important and favorite food for fish and other aquatic animals.

For fun, wanted to share this great online key – Macroinvertebrates.org - for identifying aquatic macroinvertebrates (aquatic invertebrates that you can typically see with your eyes). Hoping your son finds this helpful in his future lake explorations. Here also is a link to a page on the LifeinFreshwater.net website with more information specifically about freshwater scuds.