Phyllidia varicosa Care Guide
Phyllidia varicosa is a warty Indo-Pacific nudibranch that feeds on sponges and releases toxins when stressed, making it unsuitable for community tanks.
Compiled by Aquairi from published sources · Published · Updated
Overview
Phyllidia varicosa is a dorid nudibranch of the family Phyllidiidae, described by Lamarck in 1801. It is a large sea slug reaching at least 115 mm in length, recognised by three to six longitudinal tuberculate ridges along the back. The ridge bases are blue-grey with yellow-capped tubercles, and a black stripe runs along the sole of the foot. The species is distributed throughout the Indo-West Pacific, including the central Pacific and the Red Sea.
Taxonomy
- Family: Phyllidiidae
- Genus: Phyllidia
- Scientific name: Phyllidia varicosa
- Authority: Lamarck, 1801
Habitat
The species inhabits tropical reefs across the Indo-West Pacific. Like other phyllidiids it is associated with sponge-rich substrates where its prey occurs. Its bright black, white and yellow pattern functions as aposematic (warning) coloration; juvenile sea cucumbers of the species Pearsonothuria graeffei are reported to mimic this colour pattern for protection.
Aquarium requirements
- Water type: saltwater (marine reef)
- Minimum tank volume: 100 L
- Temperature: 24-26 °C (75-79 °F)
- pH: 8.1-8.4
- Specific gravity: 1.024-1.026
- Alkalinity (KH): 8-12 dKH
- Adult size: 4-8 cm in aquarium records; wild specimens reach 11.5 cm
- Lifespan: about 1 year
Diet
Phyllidia varicosa is a specialist carnivore that feeds on sponges. This narrow dietary requirement is the main reason it rarely survives in captivity: most aquariums cannot supply a continuous source of the specific sponges it consumes, and the animal slowly starves.
Compatibility
The slug itself is not aggressive, but when stressed or injured it releases toxic chemicals into the water. In an enclosed aquarium these toxins can harm or kill fish and other invertebrates. Because of its specialist diet and chemical defence, the species is not recommended for mixed community or reef tanks and is best left in the wild.
Phyllidia varicosa Breeding Guide: Toxic Sponge-Feeding Nudibranch
Overview
Phyllidia varicosa is a dorid nudibranch widely distributed throughout the Indo-West Pacific, including the central Pacific and the Red Sea. It grows to at least 115 mm. Its tubercles are blue-grey at the base and capped with yellow, and the foot sole carries a black longitudinal stripe; the warning coloration advertises its toxicity to predators.
Diet and Chemical Defence
P. varicosa lacks a radula and other buccal hard parts and feeds by sucking on sponges, having been recorded feeding on sponges including the genus Hymeniacidon. From Hawaiian specimens the toxic sesquiterpene 9-isocyanopupukeanane was identified in the defensive mucous secretion and was also found in the sponges it eats; extracts deter fish feeding and were reported lethal to fish and crustaceans.
Reproductive Mode
As a dorid nudibranch, P. varicosa is a simultaneous hermaphrodite; like other nudibranchs it cross-fertilizes and deposits egg masses. Detailed spawning data for this species in captivity are not documented in the consulted sources.
Common Challenges
The species depends on specific sponge prey that is rarely available in aquaria, so specimens typically starve. It also secretes toxins that can harm tankmates when the animal is stressed. These factors, together with the dispersing larvae typical of nudibranchs, mean it is not bred in home systems.