Mating is never easy when you have an unsightly bulbous appendage protruding from your head.

But the male Asian Sheepshead Wrasse has even greater problems to contend with.

The female wrasse is endowed with the extraordinary ability to unexpectedly switch gender, a change which not only scuppers any burgeoning relationship with the male but also creates another headache for him - a new love rival.

The gender-bending ability of the wrasse has been captured in detail for the first time for BBC Blue Planet II which airs on Sunday.