Mystery Mushroom-shaped Deep Sea Jelly Animal

Image: Just et al.

Scientists have finally revealed the Mystery Mushroom-shaped Deep Sea Jelly Animal to an excited and baffled populace! Isn't it exciting and baffling?

Numerous specimens of the mystery animals were collected during a study that explored the continental slope off south-east Australia at depths between 400 and 1000 metres (1,300 to 3,300 ft). That was way back in 1986, and the scientists involved have finally gotten round to publishing the description. Was that thing in development hell or what?

The creatures look like tiny mushrooms, each standing less than a centimetre (0.2 in) tall. At the bottom of the stalk is a mouth, at the other end is a disc filled with branches of the gastrovascular canal, which is where all the food would flow and dissolve into the body. This branching system provides them with their generic name: Dendrogramma. Oddly enough, they found two different species! D. discoides and D. enigmatica.

Now all we have to do is figure out what on earth and sea they actually are...

Image: Just et al.

They initially look like some kind of extremely strange member of cnidaria. They do appear to be diploblastic, which means they have just two layers of cells, an outer skin and an inner gastric layer stuck together with jelly. That's just like cnidarians, but it's also like the comb jellies. So maybe it's an extremely strange comb jelly? It's difficult to tell because the Mystery Mushrooms have no tentacles or stinging cells like jellyfish, no colloblasts like comb jellies and no sense organs at all.

So perhaps it's an extremely strange whole-other-thing-unto-itself? That would be amazing since animals can be divided into five main groups: cnidaria, comb jellies, sponges, Placozoa (tiny, squishy, flat things) and Bilateralia (everything else. Basically all the animals that have a face). Discovering a whole new group would be extraordinary and a great aid in figuring out the ancient, evolutionary roots of animal-kind.

The researchers also suggest a possible connection to a group of pre-Cambrian animals called Trilobozoans, who are also weird and confusing. It's difficult to imagine these things surviving for 500 million while everything around them was utterly transformed, but who knows?

Image: Just et al.

For now, the mystery continues. And it could go on for a long time to come. Due to the method of preserving the specimens it's almost impossible to genetically analyse them. The researchers who first discovered them returned to the site a couple years later but couldn't find them again. No-one else seems to have ever come across them before or since. It isn't even known what side up they go! They were initially collected by - essentially - tying a bucket to a long piece of rope and dragging it across the ocean floor to see what it picks up. No-one has seen a Mystery Mushroom doing its thing.

It's as if a scientist took 30 years to publish a dream he had one time! Or maybe it's just a flatworm living life as a pillar-hermit?