About Phyllidia coelestis Bergh, 1905
This species of sea slug, scientifically named Phyllidia coelestis Bergh, 1905, can reach a maximum length of 6 cm. It has an elongated, slug-shaped body. Its mantle has a grey-blue base color, and the mantle margin is covered in many small tubercles. Larger tubercles with yellow caps run along the mantle's median line. Three black longitudinal lines are also present on the mantle: two are positioned one on each side of the mantle, and the third runs along the median line, ending in a Y-shape at the anterior portion of the body. This characteristic Y-shaped end to the median black line is a distinctive feature used to identify this species. The rhinophores of this sea slug have lamellae, and are yellow in color. Phyllidia coelestis is found in the tropical Indo-West-Pacific region. It inhabits the external slope of coral reefs, the top of reefs, and reef lagoons, and can be found at depths down to 30 meters. Confirmed recorded locations include the western Pacific Ocean, the South China Sea, the Timor Sea, and across the Indian Ocean as far as South Africa.
