|90 cm long specimen of the Spanish dancer, at night in Bali|
(Ruppell & Leuckart, 1828)
The Spanish dancer, scientific name Hexabranchus sanguineus (literally meaning "blood-colored six-gills"), is a dorid nudibranch, a very large and colorful sea slug, a marine gastropod mollusk in the family Hexabranchidae.
The Spanish dancer is a large dorid nudibranch which can grow up to a maximum length of 60 cm. However, the commonly observed size is between 20 and 30 cm long. Its body coloration is generally orange-red speckled with multiple small white dots but it also can be uniformly bright red or yellow with red scattered spots. Its body is soft and flattened, the anterior dorsal portion has a pair of retractable rhinophores and the posterior part has six contractile gills inserted independently in the body. The pair of oral tentacles are constituted by a fin flexible membrane provided with large digital lobes.
In a normal situation when the animal is crawling, the edges of its mantle are curled inwards creating a peripheral blister. If the animal is disturbed, it unfolds its edges and can swim through contractions and undulations of the body to move away from the disturbing element. Its common name, Spanish dancer, comes from this particular defense.
The egg ribbon of Hexabranchus sanguineus in the northwest Hawaiian Islands
Spanish dancer in daylight, Dahab
Spanish dancer, a posterior view showing the gill rosette
Encountered at night on the North coast of East Timor
Distribution and habitat
The Spanish dancer is widespread throughout the tropical and subtropical waters of the Indo-Pacific area from the eastern coasts of Africa, Red Sea included, to Hawaii and from south Japan to Australia.
It likes rocky and coral reefs with many sponges and shelters from 1 to 50 meters deep.
During daytime, the Spanish dancer hides away from the light in the crevices of its natural habitat to only come out late at night. It feeds on various species of sponge. Like all nudibranchs, it is hermaphrodite and its bright red to pink egg ribbon has a spiral shape related to the size of the animal so relatively large. The latter is coveted by some other species of nudibranch as Favorinus tsuruganus or Favorinus japonicus. The Emperor shrimp, Periclimenes imperator, is a commensal shrimp that is commonly found living on Hexabranchus sanguineus.
- Rudman, W.B., 1999 (March 31) Hexabranchus sanguineus (Ruppell & Leuckart, 1828). [In] Sea Slug Forum. Australian Museum, Sydney.
- Valdés Á. (2002). "How many species of Hexabranchus (Opisthobranchia : Dorididae) are there?". Molluscan Research 22(3): 289-301. doi:10.1071/MR02012, PDF.
- http://www.seaslugforum.net/hexasang.htm Seaslug forum
- DELUNEL Anthony, WARREN Lindsay, COROLLA Jean-Pierre, MITEL Cédric, in : DORIS, 17/7/2014 : Hexabranchus sanguineus (Rüppell et Leuckart, 1830), http://doris.ffessm.fr/fiche2.asp?fiche_numero=411