Spanish Dancer (Hexabranchus sanguineus) Breeding Guide

Hexabranchus sanguineus is a large hermaphroditic nudibranch that lays spiral red egg ribbons defended by sponge-derived macrolides. As an obligate sponge feeder with planktonic larvae, it is not a realistic home-bred species.

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.