Sea Butterfly: Real Snail or Mythical Creature?

Naked Sea Butterfly

Not only does this species sound completely made-up, it also looks a bit like that, too — and the name doesn’t appear to make a lot of sense to start with. A butterfly, in the sea? There’s no way. But I’m here to tell you that they are one hundred percent real.

Let’s take a look at this fabulous

What is a Sea Butterfly?

‘Sea butterfly’ is a catch-call term for a few different Thecosomata species, some of which are now extinct. These are:

  • Cavoliniidae
  • Clionidae – also known as sea angels
  • Creseidae
  • Cuvierinidae
  • Cymbuliidae
  • Peraclididae
  • Praecuvierinidae – now extinct
  • Limacinidae

One of the most well-known species, thanks in no small part to the game ‘Animal Crossing‘, is known as the naked sea butterfly, common clione, sea angel, or the scientific name Clione limacina. In the game, the ‘naked’ part of the name has been dropped. It is a family game, after all.


Different species look a little different from each other in the sea butterfly family. The only thing they all have in common is that they rarely look like the snails you’re accustomed to seeing.

All sea snails are gastropods, but not all of them have shells. The ones that do have shells, don’t always have shells the whole way through their lives. And sometimes, the shell is basically transparent, so you might not even see it even if it were right in front of you.

It almost sounds made up, doesn’t it?

The sea butterfly looks more like an elephant snail than the actual elephant snail does. It has two elephant ear-like lobes, which are scientifically known as parapodia. These are almost like little flippers, guiding the gastropod as it swims and floats around in the currents of the sea. Some people might refer to them as ‘wings’, hence the butterfly-themed name.

Sea butterfly - Clionidae

The parapodia appear where the actual body (foot) of the snail would be. (The slug-like part.)

The Desmopteridae family of sea butterflies don’t have a shell at all. They’re all wings (parapodia) and no shell.

The Cavoliniidae family, on the other hand, tends to always have shells, at all stages of life.

Sea butterflies in the Cymbulioidea family are very diverse in terms of shell. Some individuals have one but others don’t, and some only develop a shell later on in life. Some will grow a ‘fake’ shell, known as a pseudoconch, make of gelatinous cartilage material.


Just as with different features, different species will grow to different sizes.

The naked sea butterfly can grow to a maximum length of around 2 inches (5 cm), and this is the largest type of sea angel from the Clionidae family.

The majority of them are less than half that size, with many growing to a maximum of around 0.4-inches (1 cm).


There are very few gastropods that have evolved to live a life in the open oceans or seas, but that’s exactly that this one has done. The parapodia help to sail or guide them through the waters, allowing them to live the pelagic lifestyle.

You will find various species of sea butterfly in almost all oceans and seas, from the coldest poles to the hottest tropics, and in all sorts of depths.

Cavoliniidae is found in all warm oceans, traveling between them. This makes the species circumglobal. It also prefers some of the deepest waters, up to 6560 feet (2,000 meters) in depth.


I am going to tell you what they eat, but first I’m going to share the story of how they eat — because that, in itself, is quite fascinating.

Sea butterflies fish for food. They don’t use a rod and fishing line; instead, they use a fishing net created from mucous. The net is much, much bigger than they are, often up to 1.9-inches (5 cm) across.

Most gastropods in that family are lazy feeders, using the net to catch plankton and other, mostly plant-based items.

Can You Have a Sea Butterfly As a Pet?

Sea butterflies are essential for ocean life, which means they should really be left right where they are. As well as being a huge part of the food chain for ocean creatures, they are also a very important part (up to 12%, it is believed) of a process known as oceanic carbon cycle.

They feed fish which then go on to feed mammals such as polar bears, penguins, and humans. Some whales also eat them, along with a range of sea birds. Sea angels also likely wouldn’t exist without them, because sea butterflies are their main food source.

If sea butterflies were to be hunted to extinction for the pet industry (which commonly happens, as is the case with Cuban painted snails), the ocean – and the planet – would be in rather a lot of trouble.

That aside, they have a pattern of behavior that is not well suited to life in captivity. The tend to follow plankton, migrating up and down in the ocean column as day and night passes. You’ll find them on the water’s surface mostly at night. During the day, they can descend to incredible depths. You will not be able to mimic this sort of habitat in an aquarium setting.

Sea Butterfly vs Sea Angel: What’s the Difference?

Sea angels prey on and eat sea butterflies. I’d say that was a pretty big difference. The butterfly uses its parapodia to flipper (or fly) itself away from predators like the sea angel. Sea angels also lose any shell they may have by the time they reach adulthood, whereas some sea butterflies go the other way and acquire a shell later on in life. The two creatures look similar and come from the same family, but they are different in more ways than just prey and predator.


Can a Sea Butterfly Fly?

No, a they cannot fly. Being sea snails, they’d soon dry out in the open air. They can appear to fly or glide in the water, though.

Are Sea Butterflies Rare?

Sea butterflies are actually thought to be one of the most abundant gastropod species around the world. They’re food for a huge array of ocean-swelling creatures, so without them, we’d be without a lot of other sea life, too.

How Much is a Sea Butterfly Worth in Animal Crossing Game?

Nook’s Cranny will give you 1,000 for your sea butterfly. With C.J., you’ll bag 1,500 bells. Just make sure you don’t get it mixed up with a sea moth!

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