Sea Cucumbers Are Surprisingly Speedy, And Not The Lazy Slugs We Thought


Katy Evans

Katy is Managing Editor at IFLScience where she oversees editorial content from News articles to Features, and even occasionally writes some.

Managing Editor

Holothuria scabra, one of the sea cucumber species studied. Admittedly, it doesn't look particularly speedy. unterwegs/Shutterstock  

Sea cucumbers may not have the most exciting of reputations. Yes some of them look fabulous, but to be honest they’re shaped like a vegetable and it was thought they moved about as fast as one too. Not so, says a new study. Sea cucumbers are surprisingly speedy.

According to brand new research published in the Journal of Animal Ecology, they can up sticks and zip around the ocean by blowing themselves up like a balloon and riding ocean currents. Pretty nifty, huh?


Sea cucumbers are often referred to as sea slugs thanks to their slow movements and sedentary lifestyle, though they are not true sea slugs, which are technically sea-dwelling gastropods. Instead, sea cucumbers are echinoderms, more closely related to starfish.

Like starfish, it was thought that sea cucumbers crawled about slowly on the ocean floor, chilling out and hoovering up any food particles they come across on the seabed. As with most bottom-dwelling sea beasties, if they do travel about it’s in their larval stage, before they become adults and get lazy.

Now, researchers led by Annie Mercier of the Mercier Lab at Memorial University, Canada, have discovered that they actually have a very efficient way of traveling long distances, and, of course, they have a really weird way of doing it.

Following anecdotal evidence and rumors that sea cucumbers bloat and float, Mercier and co. discovered that they do in fact bloat themselves by flooding their bodies with water, reducing their density until they float, and then apparently throw caution to the wind and catch any passing current.  


“They take up water from all the orifices they can, including through the anal opening,” Mercier told National Geographic. Which shouldn’t be surprising, since sea cucumbers use their anus for everything from pooping (obviously) to attacking predators by ejecting their own intestines (surprise!).

To study this behavior in the lab, the team tested their reactions to increased levels of salt or sediment by creating strong currents and storm conditions. Within minutes the unimpressed cucumbers gathered themselves up and fled. Some even increased their water-to-flesh radio by 700 percent, for a speedier getaway.

Data gathered in the field clocked some of these cucumbers zipping around at a speed of 90 kilometers (56 miles) per day, which is even faster than their speed as larvae.

Though only observed in two species so far, this knowledge that sea cucumbers may move much further than thought could be vital for the survival of the species. Tasty to both animals and humans, 16 species of sea cucumbers are listed on the IUCN’s Red List of endangered species, mainly thanks to demand in Asia.    


With natural stock depleting – the delicacy can go for hundreds of dollars – commercial fishing exploits are decimating ecological habitats, and local fishing resources, in their desperation to get their hands on them. This new information means that previous population estimates in certain locations may be wrong, affecting conservation efforts and fishing quotas in the future. 

[H/T: NatGeo]


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