Neomysis integer is a species of opossum shrimp found in shallow marine bays and estuaries of Europe, with a transparent greenish or brownish body and a large cephalothorax.

The exopod (the outermost branch) of the second antenna forms an elongated scale with bristles round its edges and extends forward into a sharp point.

The head and first six segments of the thorax are covered by a protective carapace which extends forward in a triangular plate with a depressed centre between the eyes.

Over the succeeding years, the sea water gradually turned to freshwater and Neomysis integer was the only opossum shrimp that survived.

[4] These opossum shrimps are frequently found in large numbers and filter small food particles out of the water, occasionally consuming larger prey.