Nudibranch spp.

iNaturalist · HTTP://CREATIVECOMMONS.ORG/LICENSES/BY/4.0/

Hilutungan Channel hosts a diverse nudibranch assemblage — Chromodoris, Hypselodoris, and Phyllidiella species are found on virtually every dive, with electric-blue, orange, and spotted specimens visible on coral rubble and sponge surfaces from 8 m down. Nudibranchs are key indicator species for reef health and chemical diversity — their bright aposematic colours advertise toxins sequestered from sponge prey. The channel's sanctuary-protected rubble zones and sponge gardens support one of the highest nudibranch species densities on Mactan Island.