This Bizarre Sea Worm Branches Like a Tree, And Each Segment Has Its Own Butt

Nature is so strange. You can have worms residing in the deep sea that are completely butt-free… when in reef-dwelling segmented worms whose bodies branch like a tree from its head, each and every department finishes in a individual butt.


This species is known as Ramisyllis multicaudata, and it is probably the strangest worm on the earth. It was first identified in 2006, and formally described in 2012. Now, for the 1st time, experts have carried out a specific analyze of its anatomy, ultimately revealing additional about this enigmatic creature – and increasing even much more queries about how it lives its bizarre everyday living.

“Our investigate solves some of the puzzles that these curious animals have posed ever considering the fact that the first branched annelid was discovered at the conclusion of the 19th century,” claimed evolutionary biologist Maite Aguado of the College of Göttingen in Germany.

“Having said that, there is however a very long way to go to completely understand how these interesting animals reside in the wild.”

R. multicaudata appears to be to be the extremely embodiment of introversion. It life symbiotically in sea sponges to shallow depths of 20 meters (66 toes) in the waters off the north coast of Australia, its head buried deep in its residing home.

As it grows, its bristled branching human body, with diameters all over 1 millimeter, extends along channels in the sponge. Only the really ends of those branches – the worm’s numerous posteriors – adhere out, offering the sponge a marginally patterned look.

buttsR. multicaudata in a Petrosia sponge. (Glasby)

It really is a curious existence, and one particular that has puzzled biologists. The worm is pretty fragile, and breaks apart quite simply, earning it terribly tricky to dissect and examine.

However, immediately after painstaking work working with a blend of procedures including histology, digital optical microscopy, immunohistochemistry, confocal laser microscopy, and X-ray computed microtomography, an worldwide staff of biologists has managed to analyze the ins and outs of R. multicaudata‘s anatomy.


By examining the worm enveloped within just the host sponge, they managed to present that the overall, advanced, branching worm is enormous, thoroughly filling the sponge’s canals and cavities. They also acquired a few-dimensional photos of the worms and their inside anatomy, as well as the labyrinthine sponges they call residence.

For the initial time, they were being able to ensure that when the worm’s system divides and branches, so way too do its inner organs. Digestive tracts break up, and the worm’s guts operate by way of the new branches as well as the previous.

Fascinatingly, this peculiarity requires an anatomical structure never ever ahead of witnessed in any other animal – what the researchers have identified as muscle mass bridges. These type anywhere the worm bifurcates, crossing involving the break up organs.

The muscle mass bridges are also proof that the worm splits when it truly is mature, not as a juvenile, and can also be applied to observe which department was the unique and which a person split, which is practical for understanding the animal’s growth.

worm faceGlimpse at the small facial area (base remaining)! (Ponz-Segrelles & Glasby)

When the worm wants to reproduce, it takes advantage of its branches to do so. A department tip will variety with gametes within, named a stolon the stolon will detach from the mother or father worm to swarm and reproduce with other stolons prior to dying, even though the guardian life on.

In their examine, the scientists ended up equipped to ensure that these stolons build brains and eyes when still connected to the dad or mum worm. Then, when the stolon breaks no cost, it is wholly autonomous, ready to swim and breed.


Nevertheless, there is certainly a person secret we still really don’t have an remedy for: With just one particular head, buried deep in a sponge, how and what does R. multicaudata eat?

“This study has concluded that the intestine of these animals could be useful, however no trace of food stuff has ever been seen inside of them and so it is nevertheless a thriller how they can feed their substantial branched bodies,” Aguado stated.

“Other inquiries elevated in this examine are how blood circulation and nerve impulses are influenced by the branches of the system.”

All individuals butts, and the worm’s not even utilizing them… at the very least, not in a way that we can at the moment understand.

Now that the groundwork has been laid, maybe long term exploration will have an less difficult time comprehending how R. multicaudata lives – and how the heck it progressed to turn out to be the bizarre and excellent way it is.

The investigate has been published in the Journal of Morphology.