Black-faced blenny 2007) and "T. tripteronotum" (Risso, 1810). Besides "T. delaisi", all species are endemic to the Mediterranean Sea. The species "T. delaisi" is subdivided in two subspecies: "T. delaisi delaisi" in the Mediterranean Sea and "T. delaisi xanthosoma" in the Atlantic Ocean. The subspecies can be distinguished by their courtship behaviour: "T. delaisi delaisi" court in free water and "T. delaisi xanthosoma" stay on the ground for courtship behaviour. The speciation process is still under discussion and several hypotheses have been proposed. Black-faced blenny The black-faced blenny ("Tripterygion delaisi") is a small benthic fish from the family Tripterygiidae (triplefin-blennies). It occurs
Grass goby Grass goby The grass goby ("Zosterisessor ophiocephalus") is a species of goby native to the Mediterranean Sea, the Sea of Azov and the Black Sea. It is currently the only known member of its genus. Grass gobies can grow up to long. The head crown, nape, throat, belly, and bases of the pectoral fins are covered by cycloid scales and the gill covers are naked. The abdominal sucker has no blades and does not reach the anus. The mandibulae are protrusive, and the skin soft, with mucus. Their coloration is green-brown, patterned with merging brown spots. The cheeks have round