Hexabranchus sanguineus (Spanish Dancer) Care Guide
Hexabranchus sanguineus is a large red dorid nudibranch that swims by undulating its mantle. A sponge specialist, it is difficult to feed in captivity.
Compiled by Aquairi from published sources · Published · Updated
Overview
Hexabranchus sanguineus is a large dorid nudibranch of the family Hexabranchidae. It commonly grows to about 25 cm, with some Red Sea reports reaching 40 cm. The soft, flattened body carries retractable rhinophores at the front and six contractile gills at the rear, plus a pair of oral tentacles with digital lobes. Its common name, Spanish dancer, refers to a swimming display in which it unfurls its mantle edges and propels itself with rhythmic undulations.
Taxonomy
- Family: Hexabranchidae
- Genus: Hexabranchus
- Scientific name: Hexabranchus sanguineus
- WoRMS authority: (Rüppell & Leuckart, 1830)
Habitat
The species occurs in the Red Sea, the western Indian Ocean, French Polynesia and the western Pacific. It lives on rocky and coral reefs rich in sponges, at depths from about 1 to 50 metres. During the day it hides from light in crevices, becoming active at night.
Aquarium requirements
- Water type: saltwater (marine reef)
- Minimum tank volume: 200 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: 15-40 cm
- Lifespan: about 1 year
Diet
Hexabranchus sanguineus is a carnivore that feeds on sponges of the family Halichondriidae. It sequesters defensive compounds from these sponges and transfers them, as macrolides, into its tissues and egg ribbons. Supplying the correct live sponges in an aquarium is impractical, so the animal usually starves in captivity.
Compatibility
The slug is peaceful toward tank mates but its specialised diet makes long-term keeping unrealistic in a standard reef system. It is best housed only in a dedicated sponge tank by experienced aquarists, if attempted at all.
Breeding
The species is hermaphroditic and lays a coiled egg ribbon that ranges in colour from bright red to pink. Defensive chemicals derived from its sponge diet are passed into the egg ribbon, protecting the developing eggs.
Spanish Dancer (Hexabranchus sanguineus) Breeding Guide
Overview
Hexabranchus sanguineus, the Spanish dancer, is a large red dorid nudibranch found in the Red Sea, the Western Indian Ocean, French Polynesia and the Western Pacific. It commonly reaches about 25 cm, with some Red Sea reports to 40 cm. When disturbed it unfolds its mantle edges and swims by contractions and undulations of the body, the motion that inspired its common name.
Diet and Chemical Defence
The Spanish dancer consumes sponges of the family Halichondriidae and derives a potent defensive chemical from them. It transfers these defensive compounds into its egg ribbons via macrolides, providing chemical protection to the otherwise vulnerable eggs. The commensal emperor shrimp Periclimenes imperator is commonly found living on it.
Reproductive Mode and Egg Ribbons
Like all nudibranchs, the Spanish dancer is a hermaphrodite. Its egg ribbons range in colour from bright red to pink and have a spiral shape whose size is related to the size of the animal; this characteristic coiled ribbon is sometimes called a Spanish dancer rose.
Common Challenges
Despite producing conspicuous egg ribbons, the species is an obligate sponge feeder whose specific prey is rarely sustainable in aquaria, so adults usually starve. Its larvae are planktonic and disperse in open water, so rearing offspring to settlement in a closed system is not feasible.