Meet The Worm With Hundreds Of Butts That Can Detach And Grow Brains


Jack Dunhill

Social Media Coordinator and Staff Writer

clockMay 7 2021, 17:05 UTC
booty worm

Fragment of the branched worm. Image Credit: Ponz-Segrelles G, Glasby CJ, Helm C, et al. Integrative anatomical study of the branched annelid Ramisyllis multicaudata (Annelida, Syllidae). Journal of Morphology. 2021;1-17.

Australia truly is the land of ridiculous creatures. From vicious magpies to moths too big to fly, the land of the upside-down is home to freakish sights of nature that would seem out of place anywhere else in the world.  

Now entering the stage, however, could be the weirdest of them all – the worm with one hundred buttholes.  


Making a home in the internal canals of sea sponges, Ramisyllis multicaudata is an insane marine worm that is just one of only two known species with a branching body of one head and multiple rear ends. Native to Darwin, Australia, these worms use their unique body shape to spread out across the many tunnels within the sponge and live symbiotically with their host.  

In a new study published by an international team in the Journal of Morphology, researchers looked within to understand the internal workings of this branching worm, and how it can spread throughout the labyrinth that it calls home. Alongside this, they also uncovered a peculiar system of fertilization that involves the detachment of reproductive units which then develop their own brain to find their way through the sponge’s canals. 

The Ramisyllis multicaudata was first discovered in the late 19th Century, and their distinctive appearance and behavior led them to be well documented. Despite this, their internal anatomy and why their bodies are branched in this way have not been understood. In an attempt to characterize its’ internal workings, the researchers used an array of microscopy, histochemical, and observational techniques to understand how these worms live and use their bodies to their advantage. 

They discovered that the worm branched an extreme number of times, resulting in a slew of anuses that could be in the hundreds. 


“We were able to count more than 500 [branches] in one specimen, but we think that they can easily reach 1,000,” said M. Teresa Aguado, author of the study and evolutionary biologist at the University of Göttingen, reports Gizmodo

Impressively, these branches are all theoretically self-sufficient, as with every division into a new branch comes with a division of internal organs too. This way, each section of their body has a fully-functioning set of internal organs, connected to the previous by a muscular bridge. This is the first time such behavior has been recorded. 

A sample of the worm dissected out of a sponge. Image Credit: Ponz-Segrelles G, Glasby CJ, Helm C, et al. Integrative anatomical study of the branched annelid Ramisyllis multicaudata (Annelida, Syllidae). Journal of Morphology. 2021;1-17.

However, this is not the most incredible bit about the worm that the researchers uncovered. Every time the animal wishes to reproduce, the posterior ends develop into reproductive units called stolons. As these develop, they also form a new brain and even eyes, and can then detach and travel through the sponge canals to reproduce. Not only does this animal have hundreds of butts, but it also has hundreds of butts that turn into independent, reproducing worm parts. 

Now, the researchers hope to understand more how these worms live and reproduce, as their incredible morphology still has a lot to reveal. 


"Our research solves some of the puzzles that these curious animals have posed ever since the first branched annelid was discovered at the end of the 19th century," explains Aguado in a statement.

"However, there is still a long way to go to fully understand how these fascinating animals live in the wild. For example, this study has concluded that the intestine of these animals could be functional, yet no trace of food has ever been seen inside them and so it is still a mystery how they can feed their huge branched bodies. Other questions raised in this study are how blood circulation and nerve impulses are affected by the branches of the body." 



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