Hermit crabs all over the world are increasingly using plastic and other waste products to protect their bodies, rather than traditional shells, scientists have found.
Hermit crabs need to protect their soft abdomen in shells, but using plastic – the most common waste found in seawater – and other anthropogenic materials in this role could be altering their behaviour, scientists from the University of Warsaw report.
The article described how, using novel research methods associated with iEcology (internet ecology – the use of various online data sources as a tool in ecological research), the emergence of a new behaviour in hermit crabs was demonstrated. The animals started to use plastic lying in the water as their armour.
“Hermit crabs need to protect their soft abdomen,” said Professor Marta Szulkin. “They usually do this by hiding in shells left behind by dead crustaceans. One such hiding place is not enough for a lifetime because of the crab’s development, but also because of intra-species competition.”
The scientists analysed photos of hermit crabs from the Coenobitidae family published on social media and other online platforms.
“In the photographs, we discovered a total of 386 individuals using ‘artificial shells’ – mainly plastic caps, but also made from broken necks of glass bottles or metal ends of light bulbs.
“According to our calculations, 10 out of 16 species of land hermit crabs in the world use this type of shelter. This unusual behaviour is observed in all tropical regions of the Earth,” Prof. Marta explained.
In the article, the scientists present the presumed evolutionary directions of individual species of hermit crabs in the Anthropocene. Among the factors influencing the choice of “artificial shells” by these animals, the researchers highlight: sexual selection, the weight of plastics, odour stimuli, and the possibility of camouflage in polluted environments.
The scientists will now do further research to determine reasons for this behaviour and its impact on the evolution of hermit crabs.
“These analyses will deepen our understanding of the consequences of plastic pollution in marine ecosystems, as well as the evolution of species in the context of new evolutionary pressures associated with the Anthropocene,” added Prof Marta.
