Polyphemus are a predatory genus of water flea.

The two species have four pairs of legs with exopodites, or outer branches.

[3] The legs are adapted for catching mobile prey, generally smaller species of water flea such as young Daphnia and Bosmina.

[4] Polyphemus has two compound eyes that are fused to form a single unit, with a zoned set of receptors.

[5] This zoned structure is paired with an eye-control system that allows the Polyphemus to visually distinguish target size to avoid predators and track prey.