The Spanish dancer Hexabranchus sanguineus is a dorid nudibranch mollusk. It got its name from their resemblance when swimming, to the skirts of a Spanish Flamenco Dancer. 

Appearance

These unusual mollusks have an elongated oval shape. Their color varies from bright red to orange with red spots.

Spanish dancers can grow up to 60 centimeters in length, making them the largest known nudibranch. When crawling along the bottom, their mantle folds inward to the body. When they are uncomfortable, they throw back their mantle and can swim by rocking their body. From the outside it looks pretty spectacular.

Habitat

These mollusks live in the tropical and subtropical Indian Ocean and the Western Pacific Ocean, from Africa to Hawaii and from Australia to Japan.

The Spanish Dancer is nocturnal and is usually only seen at night. In rare cases, these mollusks can be seen in a dark crevice during the day.

What do they eat?

Mollusks feed mainly on the sponges of Galichondria. They absorb toxins from sponges, which provide them with protection from predators. Over time, these toxins build up in their body, making Spanish dancers a very dangerous treat.

Can it be kept in a home aquarium?

Due to their highly specialized diet of certain types of sponges, Spanish dancers are generally not kept in aquariums. Although they are listed for sale and bought by some aquarists, they will almost certainly not survive long in captivity and will die quickly in the aquarium.