Meet P. minutus, the king crustacean of the seas!
Well, not really, but these hermit crabs are key coastal ecosystem engineers and bottom-feeders.
Alongside their buddies, P. ortmanni and P. lanuginosus, they’re facing an existential threat because of… car tires?
You’re probably aware of the broader marine trash problem due to successful PR campaigns, with Instagrammable captions like:
“There will be more plastic than fish in the ocean by 2050!”
But did you know that 29 million metric tons of waste tires are generated annually (Sogabe) by the 45 most car-centric countries?
While 90% are properly handled, the rest end up in landfills and oceans, upsetting the ecosystems of our little friends.
The Death-Traps of Mutsu Bay
In the next tragic episode of our continuing climate catastrophe, scientists have recently discovered that illegal dumping of car tires in Mutsu Bay, Japan possibly creates death-traps for hermit crabs.
Because the concave inner wall of a tire prevents escape, hermit crabs cannibalize themselves or die due to starvation.
After observing large masses of crab shells inside wild waste tires, scientists set out to study how these death-traps work.
They ran two experiments:
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Field Experiment:
Scientists arranged six car tires at the bottom of the Bay, collecting captured hermit crabs monthly from October 2015 to September 2016.
Then, they measured body size and organized by species.
(Don’t worry, collected crabs were released healthy and well after measurement!) -
Aquarium Experiment:
A tire was placed inside a plastic tank filled with fresh seawater.
Ten hermit crabs (P. minutus and P. ortmanni) were placed inside and outside the tire.
After 18 hours, their positions were recorded.
The Findings
Research showed that 1,278 hermit crabs were trapped inside the six tires over the course of the year, with body size having no impact on capture rate.
That’s a small town population!
In addition:
- No crabs escaped in the 18-hour observation period.
- Escape is technically possible, but lack of footholds on the tire’s interior makes it unlikely.
- Car tires break down too slowly, meaning starvation occurs before natural decay allows escape.
Extending these findings across the vast number of tires that span the ocean…
Car tires are to hermit crabs what Chicxulub, the meteor that smashed into Earth, was to dinosaurs — a threat to their very existence.
The Bigger Picture
While this is an issue affecting one species in one location, it speaks to a broader problem.
Our current way of life is simply unsustainable.
When we pay little regard to the lives of the animals we share this planet with, we risk wiping out precious ecosystems.
Without hermit crabs:
- Fish lose a key food source.
- Species that depend on discarded shells are left homeless.
- We accelerate cascading ecological collapse.
Your Role in Change
It is the responsibility of every single one of us, including you, to be a better steward of this planet.
✅ Consume less
✅ Preserve more
✅ Consider the lives of the voiceless among us
Consider the lives of the little king crustaceans.
Sources
📌 I created the infographic using completely open-source, open-license images.
- Mediastorehouse. (2021, May 11). Print of flame tip hermit crab (Calcinus minutus), a left-handed hermit crab that is often found. Nature Picture Library Photo Prints.
- Sogabe, A., & Takatsuji, K. (2021). Marine-dumped waste tyres cause the ghost fishing of hermit crabs. Royal Society Open Science.