Peacock blenny

In shallow waters, a head peeks out from a crevice. Behind the eye, a blue ocellus catches the eye; in a mature male, a high crest may also rise on the head. If he occupies a cavity, he may guard the eggs deposited there by multiple females.

However, in a population of peacock blennies studied in Portugal, certain young males use a completely different strategy. Too small to compete with nest guardians, they take on the appearance and mimic the courtship display of females. Thus, when a female approaches to spawn, these mimic males can slip near the nest and attempt to fertilize some of the eggs instead of the owner.

This role does not last their entire life: as they grow, they abandon this tactic and become nesting males themselves, with their own refuge to defend.

In this same population, good nests are sometimes so scarce that roles reverse once again: the established males become a coveted resource, and it is then the females that multiply courtship behaviors around them.

Even this seduction possesses an invisible part for the diver: The male’s anal glands produce a chemical signal detected by the females. Before you, however, there is only a little blenny at the entrance of a hole; behind this scene play out egg-guarding, rivalry, imitation, and seduction.