Above: Image © lineartestpilot, iStockphoto

Every now and then, a human foot washes up on the shore. In fact, 13 human feet washed up on the coast of British Columbia between 2007 and 2016. In each case, the foot was in a running shoe, and no other body parts were found.

These creepy discoveries led to all kinds of speculation. Was there a serial killer on the loose, collecting bodies and tossing their feet? Was a medical student, a mortician’s assistant or somebody else with easy access to cadavers (dead bodies) playing a morbid prank?

Scientists have helped uncover the truth by studying what happens to a dead body in the ocean. It turns out that running shoes probably allow feet to float away before underwater creatures can consume them.

Did you know? The study of decaying organisms in the ocean is called marine taphonomy.

Lobsters and crabs and pigs, oh my!

On land, different creatures quickly get to work breaking down a dead body’s soft tissues, like skin and muscles. They include decomposers, such as bacteria, and scavengers, such certain types of flies and some larger animals. However, most of these organisms don’t go underwater.

So what happens to dead bodies in the ocean? To find out, researchers at Simon Fraser University in British Columbia placed three dead bodies 100 metres below the surface of Saanich Inlet, just off the Coast of Vancouver Island. Although the researchers didn’t use human bodies for this study, they went with the next best thing: pigs! Pigs are roughly the same size as humans, have the same gut bacteria and are mostly hairless.

Using remote cameras, scientists watched what happened to the pigs’ bodies over time. Turns out that lots of underwater critters find them delicious! Two of the pigs were immediately consumed by big marine scavengers. For example, Dungeness crabs and shrimp used their strong claws and mandibles (jaws) to strip flesh from the carcasses. A shark even made a brief appearance to join the feeding frenzy! Within a month, both pigs were reduced to bones.

The third pig was placed in an area with very low oxygen, so it was not accessible to larger scavengers. Instead, it became covered in a thick bacterial mat. Then, when the water was re-oxygenated in the spring, scavengers arrived and the feeding frenzy began!

Did you know? Under cold, oxygen-poor conditions, a dead body will become covered in a fatty waxy substance called grave wax (or adipocere). This happens even in the ocean!

But what about the feet?

So dead pigs dropped in the ocean are decomposed and consumed by marine decomposers and scavengers. Because of their similarities to pig bodies, human cadavers would probably meet the same fate. The tendons and tissues holding limbs together would be degraded. And the head, hands and feet would detach from the torso.

Human bodies can end up in the ocean for all kinds of reasons. They might be accident, murder or suicide victims. Whatever the reason, these humans’ heads and hands are usually bare. However, feet are often encased in their very own flotation devices: running shoes!

Running shoes not only protect feet from scavengers, they also cause feet to float once they’re detached from the body. Eventually, ocean currents bring the feet to shore, where they scare the daylights out of unsuspecting beachgoers.

One final question

But wait. Why the increase in feet discoveries since 2007? Advances in running shoe design might be to blame. More and more, running shoe manufacturers are using air pockets and foam technology to make their products lighter. Lighter and better at transporting disembodied feet, that is!

Learn More!

About body parts washing ashore:

About underwater forensic research:

Mira Okshevsky

Mira has a Master of Science in Marine Microbiology and a PhD in Nanoscience. She is currently a postdoctoral research fellow at McGill University, where she studies how bacteria stick together is communities called biofilms. In her free time, Mira enjoys exploring the coves and beaches of her home province of Newfoundland.

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