A Newly Described Butterfly Sea Slug
Cyerce blackburnae (Moreno, Gosliner, Wilson, Krug & Valdés, 2025) is one of the rarest butterfly sea slugs at our macro dive sites in Romblon, Philippines. Scientists formally described this species in 2025. It was previously unknown to science. It belongs to the order Sacoglossa, family Caliphyllidae. Furthermore, it is one of nine new Cyerce species scientists described in the same landmark 2025 paper. Its close relatives Cyerce nigra and Cyerce katiae are also in our Marine Life Encyclopedia.
Defence by Autotomy
Like all Cyerce species, Cyerce blackburnae has large, flat, leaf-like cerata. The animal feeds on green algae of the genus Udotea. When a predator attacks, it sheds its cerata. The cerata continue to writhe on the seafloor after separation. As a result, the predator targets the moving cerata instead. Meanwhile, the animal escapes. This strategy is called ceratal autotomy. In addition, the bold colouration on the cerata warns predators of chemical defence compounds.
Finding It at Sunset Cove
At Sunset Cove Beach & Dive Resort, our guides search sandy rubble substrate near Udotea algae patches. The animal reaches 10 to 20 mm in length. Therefore, diopters and high magnification give the best results. Approach very slowly — it sheds its cerata immediately when startled. For underwater macro photographers in Romblon, the leaf-like cerata pattern creates outstanding close-up images. Consequently, this species is one of the most exciting recent discoveries at our dive sites.