Spanish Dancer Nudibranch
The Spanish dancer (Hexabranchus sanguineus) is one of the largest nudibranchs, a shell-less sea slug that can reach 40 centimeters. Its red mantle ruffles during swimming like the skirt of a flamenco dancer.
The Spanish dancer (Hexabranchus sanguineus) is one of the largest nudibranchs, a shell-less sea slug that can reach 40 centimeters. Its red mantle ruffles during swimming like the skirt of a flamenco dancer.
🧬 Field Guide Specimen: Open Spanish Dancer Nudibranch in the CRV Science Field Guide to log the specimen, see its place among the Lophotrochozoa lineages in the Cladogram Explorer, and test your recall in the Red List conservation game.
Swimming Slug
When disturbed, the animal lifts off the reef and swims by rolling waves along its mantle edge, flashing red and white. A rosette of gills on its back is retracted if touched.
Borrowed Chemical Defense
The slug feeds on sponges and stores their distasteful chemicals in its body and in its egg masses, which look like a rose-colored ribbon. Its bright color is a warning to predators. Shrimp that live on the slug share its protection.
Losing the Shell
Nudibranchs are gastropods that lost their shell as adults, an evolutionary shift that favors chemical defenses over armor.
Spanish Dancer Nudibranch at a Glance
| Property | Value |
|---|---|
| Scientific name | Hexabranchus sanguineus |
| Kingdom | Animalia |
| Phylum | Mollusca |
| Class | Gastropoda |
| Clade | Nudibranchia |
| Field Guide group | Lophotrochozoa: Mollusca (Mollusks) |
| Diagnostic feature (Field Guide) | Complete evolutionary shell loss in adult, dorsal exposed branchial plumes, undulating scarlet swimming mantle. |
| Maximum length | About 40 centimeters |
| Diet | Sponges |
See Also
- Natural selection — warning coloration
- Biodiversity — Indo-Pacific reef diversity