Predator-induced rostrum growth in shrimp

What is it about?

Individuals of the amphidromous shrimp Xiphocaris elongata have elongated rostrums below geomorphic barriers where predatory fishes are present and short rostrums in stream reaches above geomorphic barriers where predatory fishes are absent. We tested whether the elongated rostrum in X. elongata is a phenotypic modification induced by kairomones from predatory fish or alarm cues from conspecifics through exposure experiments. Rostrums of X. elongata exposed to a predatory fish grew longer than rostrums not exposed to the predatory fish.

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Why is it important?

Our study demonstrates that the elongated rostrum in the amphidromous X. elongata is a phenotypic response induced by kairomones from predatory fish. Knowledge of how kairomones and alarm cues generate a phenotypic response in prey would contribute to our general understanding of the evolutionary mechanisms responsible for chemical signals.