Phyllidia coelestis
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- Name / Latin
- Phyllidia coelestis — Phyllidia coelestis
- Brief description
- Phyllidia coelestis is a nudibranch (sea slug) of the family Phyllidiidae. The body is oval, up to 6 cm. Coloration is grey-blue with three longitudinal black lines: two on the sides and one in the centre that forms a characteristic Y-shaped pattern in front of the rhinophores. The back is covered with bright yellow tubercles; the rhinophores are usually yellow. By day it crawls actively over the reef and feeds on sponges; the colour is warning coloration, and many phyllidiids are toxic to predators.
- Size:
- up to 6 cm
- Depth:
- down to 30 m
- Habitat:
- Indian Ocean, Pacific Ocean, Andaman Sea
- Family:
- Phyllidiidae
- Type:
- Mollusc
- Activity:
- Diurnal
- Conservation status:
- Not Evaluated (NE) — species has not been assessed by IUCN
Phyllidia coelestis is a sea slug of the family Phyllidiidae.
This mollusc has an oval body up to 6 cm long. Its colour is a grey-blue base with three longitudinal black bands: two along the sides and a third in the centre that forms a Y-shaped pattern in front of the sensory organs, the rhinophores. These small projections on the head help the mollusc detect smells in the water. The back is covered with bright yellow tubercles, and the rhinophores are also yellow and are made of many thin plates that increase their sensitivity.
Phyllidia coelestis feeds mainly on sponges, from which it takes nutrients. Unlike many other molluscs, it has no radula or jaws — a feature of all members of the family Phyllidiidae.
Like other nudibranchs, this species is a hermaphrodite: one individual has both male and female reproductive organs. When mating, partners exchange spermatophores — capsules containing sperm. After that, each lays eggs, from which larvae later hatch.
Phyllidia coelestis lives in the warm waters of the Indo-Pacific: the western Pacific, the South China and Timor Seas, and the Indian Ocean as far as South Africa. It lives on coral reefs — on their tops and outer slopes — and in lagoons at depths down to 30 metres.
This slug lives on the bottom and is most active by day. Thanks to its bright colour it can move over the reef without fear of predators. The toxic substances in its body make it inedible, and its strong colours warn potential enemies.
