Phyllodesmium magnum
Encounter Rate
Spotting Difficulty
Best Season
Year-round
Depth Range
5-30 meters
Phyllodesmium magnum is one of the most extraordinary nudibranchs found in Komodo — a solar-powered sea slug that harnesses the power of the sun through stolen algae. This large aeolid nudibranch, reaching up to 14 centimetres, feeds on Xenia soft corals and has evolved the remarkable ability to retain the coral's symbiotic zooxanthellae algae alive and functioning within its own body tissue. These captured algae continue to photosynthesise inside the nudibranch's cerata (the finger-like appendages covering its back), producing sugars that supplement the animal's nutrition. This makes Phyllodesmium magnum one of the very few animals in the world that can partially photosynthesise. Its translucent body with brownish cerata gives it an appearance that closely resembles the Xenia coral it feeds on, providing excellent camouflage. In Komodo, they are found at sites with healthy Xenia soft coral growth, typically at moderate depths on current-exposed reef walls. Finding one requires a keen eye and knowledge of their specific coral host, but the reward is observing one of evolution's most creative solutions to the challenge of obtaining nutrition.
Average Size
6-10cm
Size Range
3-14cm
Maximum Size
14cm
Feeds on Xenia soft corals and retains the coral's symbiotic zooxanthellae algae alive in its body. The captured algae continue to photosynthesise, providing supplemental nutrition to the nudibranch.
Phyllodesmium magnum is one of the most extraordinary nudibranchs found in Komodo — a solar-powered sea slug that harnesses the power of the sun through stolen algae. This large aeolid nudibranch, reaching up to 14 centimetres, feeds on Xenia soft corals and has evolved the remarkable ability to retain the coral's symbiotic zooxanthellae algae alive and functioning within its own body tissue. These captured algae continue to photosynthesise inside the nudibranch's cerata (the finger-like appendages covering its back), producing sugars that supplement the animal's nutrition. This makes Phyllodesmium magnum one of the very few animals in the world that can partially photosynthesise. Its translucent body with brownish cerata gives it an appearance that closely resembles the Xenia coral it feeds on, providing excellent camouflage. In Komodo, they are found at sites with healthy Xenia soft coral growth, typically at moderate depths on current-exposed reef walls. Finding one requires a keen eye and knowledge of their specific coral host, but the reward is observing one of evolution's most creative solutions to the challenge of obtaining nutrition.
This species plays an important role in the marine ecosystem of Komodo National Park. Responsible diving practices help protect these animals and their habitat for future generations.
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Phyllodesmium magnum eats Xenia soft coral and retains the coral's symbiotic algae (zooxanthellae) alive and functioning in the finger-like cerata on its back. The algae continue to photosynthesise inside the nudibranch, producing sugars that supplement its diet.
