Abstract Biosemiotics holds that all forms of life are capable of interpretation. Regardless of the complexity of the inner world of the organism there is always found some rudimentary negotiation of code duality or the presence of incompatible codes, which necessitates a sort of ‘translation’ of those codes into meaningful action. The bioluminescent anti-predatory behavior known as counterillumination serves as an example of a relatively simple non-human behavior that nonetheless exhibits the traits of semiosis. These traits are described in detail using some semiotic terminology.