A man wearing waders standing in a tide pool examines the contents of his dip net
Emeritus museum scientist Ed Bousfield (now deceased) found that Jassa marmorata’s native range in Atlantic North America was on wave-exposed, natural shores, far from harbours and other human-built structures. Image: Kathleen Conlan, © Canadian Museum of Nature

The little shrimp-like animal Jassa marmorata was never thought to be a hitchhiker until museum collections told us otherwise. Now we’re finding out that it has been using humans to cruise the globe for centuries.

Each individual Jassa lives in the ocean in a self-built tube which it glues to its neighbour’s tube. When thousands get together, they amass a gooey colony that fouls anything solid. As a result, Jassa is infamous for blocking water pipes, clogging aquaculture nets and coating oil rigs.

This ability to stick and hold has also made this little marine creature a global hitchhiker.

Two shrimp-like creatures each with a pair of enlarged claw-like appendages on the left. One shrimp-like creature in her tube on the right.
Two Jassa marmorata males on the left. Their large front claws are a signalling device. A Jassa marmorata female in her homemade tube on the right. Image: Kathleen Conlan, © Canadian Museum of Nature.

Early explorers started it. The hulls of wooden ships were ideal for Jassa to stick and go.

The collections of the Natural History Museum in London, England reveal that the H.M.S. Challenger was likely distributing Jassa marmorata from Europe to the Southern Hemisphere as it travelled around the world from 1872 to 1876. Jassa marmorata was found swimming beside the ship in the deep ocean off of South Africa and again near Chile, far from its natural rocky shore habitat. Probably it was living on the ship’s hull and periodically falling off, duping the naturalists aboard ship into thinking that it was a local.

Through decades of dispersion—including from oyster imports and emptied ballast water—the North Atlantic native, Jassa marmorata is now fouling harbours in South America, Asia, Russia, Australia, New Zealand, Africa, the Middle East, and most of Europe. Historical collections show that it has been fouling some of these harbours since the 1800’s, though ship commerce may have been distributing it much earlier.

A Victorian illustration of a large sailing ship
As it circumnavigated the globe from 1872 to 1876, the H.M.S. Challenger unwittingly gave a North Atlantic native, Jassa marmorata, a round-the-world tour. Image: William Abbott Herdman, Public domain. Source: Wikipedia Commons

Unwitting scientists may still be giving Jassa a lift to new habitats.

A recent deep-sea expedition sampled the seabed from Europe to the North Pole. In collected samples, it found Jassa marmorata all the way there and back while no other species was so consistently found. Jassa marmorata has never been found in mud, or deeper than about 30 meters, and never in the Arctic.

Was it really living in mud at 4000 meters under the sea ice at the North Pole? Not likely.

I bet this world-class hitchhiker was living in the ship’s seawater system. Every time the hoses were used to sieve the mud from samples, a few Jassa were dislodged and contaminated the sample—and just maybe, dropped off Jassa at another destination.

An underwater scene with algae and fan worms
Plant and animal life on a floating dock edge in Australia. The North Atlantic Jassa marmorata was first detected in Australia in 1881. The beautiful fan worms (upper half of the photo) are also an introduced species. Image: Kathleen Conlan, © Canadian Museum of Nature.