Batwing Sea Slug

Image: Patrick Randall

Batwing, the world's most unlikely superhero, wraps his mighty parapodia about him as he casts his protective eye over the citizens of Sponge City. His pointy head stands to attention as his dark and violent thoughts are interrupted by a shriek of terror far below.

He sets his gory daydreams aside and sighs as he dons his most disarming smile and swoops down to give a wayward youth a good, avuncular talking to.

Just another day in the life of your friendly, neighbourhood, customer focused crime cessation officer.

Image: Patrick Randall
Siphopteron tigrinum

Batwing Sea Slugs are adorable, little slugs belonging to the Gastropteridae family.

A whole lot of them are found in tropical areas like the Indo-Pacific and the Caribbean. Others are found around Africa and a few range from California all the way up to the chill of Alaska.

Image: crawl_ray
Sagaminopteron ornatum

They're absolutely tiny! The biggest scarcely reach an inch long while many others are only a few millimetres in length!

Image: Nathalie Rodrigues
Sagaminopteron psychedelicum

Batwing Sea Slugs are part of a larger group known as the Headshield Slugs, so named because they have a kind of shield on their head (duh).

Most Headshields use this fleshy shield to plough through or under the surface layers of the seabed. They find lots of tasty worms and the like there.

Video: liquidguru

Batwings are different. They don't delve into the sea floor, which is good because they don't have the kind of flat, streamlined body that could effortlessly slip beneath the sand. Also a bunch of them have this strange, herky-jerky way of moving where it looks as if their head is hauling their body forward.

Batwings are often seen crawling on sponges and while no-one knows what most of them eat, it looks like at least some of them feed on tiny worms that live in burrows carved in those sponges. Others might eat flatworms.

Image: Christophe Cadet
Siphopteron michaeli

Without the need to do all that digging , Batwing Sea Slugs are free to use their headshield for other things.

So they turned it into a straw! Naturally.

Image: crawl_ray
Sagaminopteron ornatum going down

Their head shield is rolled up into a tube which constantly draws in water. On the other end is another tube where the water can get out.

Image: Anthony Pearson
Party food!

In between is what looks like some kind of delicious pancake roll, albeit completely the wrong colour. And made of slug.

This roll-up creates a cavity filled with a constant flow of water that helps the Batwing breathe.

Image: DuPont, Anne
Gastropteron chacmol rolled and unrolled

But what can be rolled can also be unrolled!

You know how all slugs and snails are known as gastropods, which means "stomach foot"? Well, the family name Gastropteridae comes from Gastropteron: "stomach wing"!

Video: RAKUFUKU

When disturbed, Batwing Sea Slugs unfurl their stomach wings and take to weird, water-flight.

It looks utterly exhausting! And their globular shape remains entirely unsuitable for getting anywhere quickly. Unless they were one of those cannonball guys. Shame they got rid of that head shield...

Video: TacomaUWS

I presume it all works out just fine for them but man, my arms ache to watch it. And they're not always concerned about staying right way up. They kind of tumble and spin about as they swim.

I sure hope they have a good masseuse.