Follow the Trail to Find It
Phestilla viei (Mehrotra, Caballer & Chavanich, 2020) is one of the most cleverly hidden nudibranchs at our macro dive sites in Romblon, Philippines. Its body mimics the surface of its prey coral Pavona explanulata so perfectly that it is nearly invisible. However, there is a reliable way to find it. Look for a linear trail of crescent-shaped egg masses on freshly devoured Pavona coral. Follow the trail to its head — the animal is always there. It belongs to the order Nudibranchia, suborder Aeolidina, family Trinchesiidae. Find it on iNaturalist.
An Obligate Coral Predator
Phestilla viei feeds exclusively on Pavona explanulata coral. It never feeds on any other species — making it an obligate corallivore. Furthermore, it contains symbiotic dinoflagellates (Durusdinium sp.) which give it its brown coloration and may provide supplementary photosynthetic energy. Its cerata are held flat and horizontally, giving the body an extremely flat profile that matches the coral surface. In addition, characteristic bulbous bumps along its pericardium are a key diagnostic feature. It was described in 2020 from Koh Tao, Gulf of Thailand, and named in honour of Mr. Vie Panyarachun — a marine naturalist and citizen science contributor in Thai waters.
Photographing It at Sunset Cove
At Sunset Cove Beach & Dive Resort, our guides find Phestilla viei on Pavona explanulata colonies at 7 to 21 metres depth. Therefore, search any Pavona colony carefully for crescent-shaped egg mass trails. Follow the trail to its end — the animal sits there. For underwater macro photographers in Romblon, the combination of animal and egg mass trail makes a compelling documentary sequence. Consequently, this species rewards patient, methodical searching with one of the most interesting corallivore stories in our Marine Life Encyclopedia.