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  • Writer's pictureAlly Landes

HERMIT CRABS | Take A Hit in the Property Market

Everyone will have by now seen the recent posts hitting social media featuring the stunning photography of hermit crabs inhabiting some rather unusual real estate… our broken up plastic waste!


Coenobita purpureus with artificial shell: plastic cap. Photo by Shawn Miller.

At first glance, we are impressed with the artful images by photographer Shawn Miller of these gorgeous hermit crabs strutting around in their fashionable new shapes and colours. Only then does it dawn on us that these photos are yet more evidence that we continue to destroy our natural world with our plague of plastics. When does it end?


Scientists Zuzanna Jagiello and Marta Szulkin from the University of Warsaw and Łukasz Dylewski from Poznań University conducted a thorough investigation by analysing all the images they could find posted on social media of hermit crabs with artificial protective make-shift shelling.


According to their report, “Plastic is the most pervasive element of marine waste, with many harmful impacts on wildlife. By using iEcology (i.e. internet Ecology, using online data sources as a new tool in ecological research), scientists reported on the emergence of a novel behaviour in hermit crabs related to the use of plastic or other anthropogenic materials as protective shells.”


Unbeknownst to us, “10 of the world’s 16 terrestrial hermit crabs now use artificial shells, a behaviour observed on all of the Earth’s tropical coasts.” They identified 386 individuals – 84.5% of those were using plastic bottle caps. There are also instances of crabs using broken necks of glass bottles or metal ends of light bulbs, but they don’t make up any way near as much as plastics do, nor are they as contaminating and destructive.


The team discovered four reasons which may drive individual choice for artificial shells: sexual signalling, lightness of artificial shells, odour cues, and camouflage in a polluted environment, but the research is ongoing. The team is currently looking for funding to facilitate the project further to investigate the crabs’ innovative behaviour in their natural environment.


It has become alarming that natural seashells are in such short supply, and our harmful (long-term) plastic alternatives have taken over the real estate market in the hermit crabs’ world all over the globe. Shell quality dictates a hermit crab’s fundamental quality of life, and could possibly affect their long-term evolutionary course.

You have to ask the question: Why are natural seashells in such decline to begin with?


Coenobita purpureus with artificial shell: light bulb fragment. Photo by Shawn Miller.

Zuzanna Jagiello says, “The main reason for the seashell shortage is the biodiversity crisis and the global decline in mollusk populations. Probably, there aren’t enough shells for hermit crabs.”


With plastics making up 85% (UNEP, 2021) of the world’s marine pollution, there will undoubtedly be many more perverse discoveries of wildlife being forced to adapt to our environmental destruction. The question this group of scientists is asking, is how will more individual species react in the long run physically, physiologically, and behaviourally?


We’ve seen the countless reports on marine birds, turtles, whales and dolphins ingesting stomachs full of plastics, the entanglements leading to serious injuries and/or deaths. We now know we have micro plastics in our blood, our faeces, mothers’ breast milk, in our drinking water, and most recently, found in human lungs after a study discovered we inhale a credit card’s worth of microplastics per week. We consume it because it’s found in our soils, in turn in our vegetables; consumed by our seafood and livestock, and we now inhale it because it’s also in our air. Plastics will be the end of all!


Another recent study from 2023 has now estimated that at least 171 trillion pieces of plastic are now floating in our oceans. In 2005, it was estimated at 16 trillion pieces. Experts are warning that the new figures could nearly triple by 2040 if no action is taken. The way things are still today, we are failing miserably!


The ocean covers over 70% of the planet’s surface. All 5 oceans are linked together, so no matter where we are in the world, we are all linked by ONE ocean. Coastlines are the hotspots for plastic pollution and marine fauna is affected the most.


We should have solved this global issue yesterday, and yet we don’t seem to have made any progress at all – yet we can’t give up or else it is already too late. The future of the planet concerns every single one of us. Today, we need to heal our planet once and for all so our next generation doesn’t have to pay the full price of our mistakes all by themselves. Why do we constantly procrastinate?


It’s important for us all to get out there and observe nature, take a deep look into the environment and learn from being outdoors. Only by doing so will we want to nurture and protect it more than ever once we really feel it, see it, sense it, and hear it. We are all a part of it. We need to do better.


We should conduct clean-ups every time we see plastic pollution out in nature, as it has become all of our mess. It might not be our own rubbish we will pick up, but it is in our power to make that small difference and dispose of it properly before it breaks up into more microplastics and ends up in our ocean, and eventually in our own bodies. We are all paying the price of plastic pollution with our health; animals and humans.

Coenobita purpureus with artificial shell: metal cap with a glass bottle fragment. Photo by Shawn Miller.


Have any of you seen hermit crabs using artificial protective shells? If so, where in the world have you seen them? How many? What artificial materials have you seen used?


We can all take part in reporting sightings that have proven to be valuable to science by uploading images to the iNaturalist app and social media with relevant keywords and hashtags such as #shell, #shelter, #debris, #anthropogenic, #plastic, #waste, and #hermitcrab.



Science of the Total Environment

The Plastic Homes of Hermit Crabs in the Anthropocene by Zuzanna Jagiello, Łukasz Dylewski, Marta Szulki



The authors above are currently seeking funding to investigate the innovative behaviour of hermit crabs in their natural environment. For more information, interested parties can visit the lab’s website:



Please share hermit crab photos (with or without plastic shells) on social media and through the iNaturalist app, as the data collected through these channels has proven to be valuable.



Original Story Published in the Divers for the Environment March magazine issue:

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