Spanish Dancer

Image: moments in nature by Antje Schultner
Hexabranchus sanguineus

Hey look! It's a slug!

Doing... the flamenco?

Image: Thomas Hubauer
She's certainly dressed for flamenco...

We're looking at the Spanish Dancer, a beautiful, seductive sea slug from the hot, sultry waters of the Indo-Pacific.

It's a sexy, sexy slug. Enjoy it while you can, there aren't many slugs you can say that about!

Image: mindgrow
But can she dance the flamenco?

Not only are they lovely to look at, they're also enormous! They can reach over 40 cm (16 in) long, making them one of the biggest nudibranches in the world.

The Spanish Dancer is, more specifically, a Dorid nudibranch, meaning it belongs to the superfamily called Doridoidea. They bear certain peculiarities though, so let's take a closer look! But no touching or they'll throw you out.

Image: jome jome
Rhinophores

Like other nudibranches, the Spanish Dancer sniffs out her surroundings by means of a pair chemosensory organs called rhinophores that stick out of her head like antennae. She smells or tastes the water around her to figure out what's going on and to find tasty sponges to munch on.

Image: divemecressi
See the oral tentacle reaching out like a little hand?

On either side of her mouth are a pair of sensitive oral tentacles. Most nudibranches have oral tentacles that look like actual tentacles but the Spanish Dancer's are quite different. They look like little Mr. Men hands, stubby fingers and all!

I don't suppose they use them to quite the elegant effect of flamenco dancers, but it's nice that they try!

Image: jome jome
Leafy gills

Since this is specifically a Dorid nudibranch we expect to see their gills at the tail end. And there they are! However, in other Dorids the gills are shaped like a single tree. There's a trunk that comes out of the body and then divides up into several branches. The Spanish Dancer is different in that she has 6, separate structures that each emerge from the body on their own. It's like a fluffy tail to set off the rest of their costume.

It's also why their genus name is Hexabranchus, it means "six gills."

The specific name sanguineus means "blood-coloured" and clearly comes from their rich, crimson colour. However, they don't start off like that.

Image: crawl_ray
Baby!

Young Spanish Dancers are pale and spotty. They're probably gawky and clumsy, too. They might even get bullied at slug school. At this tender age they're easily confused with several other species of nudibranch, so at least they have some friends.

Only when they mature into their art will they acquire the deep, passionate colouration of their parents. I bet they can't wait for the slug school reunion!

Spanish Dancers from the Red Sea are especially and uniformly red. Appropriately enough.

Image: Marisa or Robin Agarwal
Hexabranchus aureomarginatus

In other areas they're adorned with white patterns and gold trim. Hawaiian Dancers have even branched out into a local style of their own. They're called Hexabranchus aureomarginatus and may or may not be a separate species.

Image: Thierry Cailleux

A rare few Spanish Dancers eschew crimson altogether and are wholly attired in golden orange. That's some serious luxury.

Image: Chika Watanabe

Spanish dancers usually keep their skirts rolled up out of the way as they go about the task of day to day living.

But a Dancer can't do housework all day!

Image: Thierry Cailleux

The art, darling! The art must be free!

When the passion takes her, she unfurls her gown to its true splendour and leaps up into the waters above.

Video: Frank Lame

Her skirts whirl in a barely controlled frenzy of sensual undulations as she leaves the seabed behind her. She enjoys the titillating feel of tiny, chaotic water eddies which embrace every inch of her body as she rises ever upward.

Does her confidence know no bounds? Will she breach the water's surface and dance her way to the sky? Will she command the attention of the sun itself and teach that shining ball of light the true meaning of beauty?

Video: maikel sanders

Maybe next time. For now, she holds her skirts against her body and allows herself to descend slowly to the sea floor. The sun will have to wait.

Till then, the Spanish Dancer has one more splash of elegance to leave for us and this time it's right there on the seabed.

Spanish Dancers are hermaphrodite... because we all know a good frock when we see it. After a VERY passionate time together they both end up with a clutch of eggs to deposit, but they don't drop them in a hole in the floor. Where's the art in that?

Image: Asbjørn Hansen

Instead, their eggs are embedded in a ribbon of bright red, gelatinous material and carefully attached to a hard surface in a beautiful, spiralling rose pattern. Isn't it just the most wonderful start in life for a young, spotty Dancer?

It's reminiscent of the rose flamenco dancer's wear in their hair but there's one crucial difference: this one is toxic! It protects the eggs from predators and assorted nosey-parkers. As I say, look, don't touch.