Phyllidia varicosa
Encounter Rate
Spotting Difficulty
Best Season
Year-round
Depth Range
3-30 meters
Phyllidia varicosa is one of the most commonly encountered and easily recognised nudibranchs in Komodo National Park. Its striking appearance features a black body covered with clusters of raised blue-grey tubercles arranged in longitudinal ridges, outlined by bright yellow or orange borders. Unlike many nudibranchs that are soft and delicate, Phyllidia has a tough, leathery texture that hints at its chemical defences — it produces potent toxins that make it unpalatable to fish and other predators. The toxic mucous it secretes is so potent that it has been known to kill fish in enclosed aquarium environments. In Komodo, these robust nudibranchs are found crawling across reef walls and boulders at most dive sites, feeding on sponges from which they derive their chemical weaponry. They are large enough to spot without a guide — typically 5 to 8 centimetres — and their bold pattern makes them stand out even to divers not specifically looking for macro life. For nudibranch beginners, Phyllidia varicosa is often the gateway species that sparks a lifelong obsession with these fascinating animals.
Average Size
5-8cm
Size Range
2-12cm
Maximum Size
12cm
Feeds on sponges, particularly species of Hymeniacidon. Sequesters toxic compounds from its sponge diet and concentrates them in its skin and mucous secretions.
Phyllidia varicosa is one of the most commonly encountered and easily recognised nudibranchs in Komodo National Park. Its striking appearance features a black body covered with clusters of raised blue-grey tubercles arranged in longitudinal ridges, outlined by bright yellow or orange borders. Unlike many nudibranchs that are soft and delicate, Phyllidia has a tough, leathery texture that hints at its chemical defences — it produces potent toxins that make it unpalatable to fish and other predators. The toxic mucous it secretes is so potent that it has been known to kill fish in enclosed aquarium environments. In Komodo, these robust nudibranchs are found crawling across reef walls and boulders at most dive sites, feeding on sponges from which they derive their chemical weaponry. They are large enough to spot without a guide — typically 5 to 8 centimetres — and their bold pattern makes them stand out even to divers not specifically looking for macro life. For nudibranch beginners, Phyllidia varicosa is often the gateway species that sparks a lifelong obsession with these fascinating animals.
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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They produce highly toxic compounds in their mucous and skin that deter predators. While handling one briefly is unlikely to harm a human, their secretions can irritate skin and eyes. As with all marine life, look but don't touch.
