A groundbreaking study by experts from two Polish universities, set to be published next month, unveils a startling revelation – the majority of terrestrial hermit crab species worldwide are now using trash as shells. The research, analyzing publicly available images and past scientific literature, discovered 386 instances of hermit crabs opting for garbage over seashells. Approximately 85 percent were found utilizing plastic caps, while the remaining crabs favored metal and glass. This behavior was observed in 10 out of the 16 land hermit crab species, spanning tropical regions from Africa to Central America.
The study, slated for publication in the Science of the Total Environment journal, marks the first confirmation that the use of artificial materials by hermit crabs is a global phenomenon. Plastic, identified as the most pervasive element of marine waste with harmful impacts on wildlife, emerged as the primary choice for these resourceful crustaceans.
The researchers proposed several factors influencing this behavior, including the potential for better camouflage in polluted environments, scarcity of fitting seashells, unique shells for sexual signaling, reduced weight of artificial shells, and the role of odor cues. A 2021 study also revealed hermit crabs being attracted to chemicals emitted by plastic.
Despite the adaptability of hermit crabs, plastic poses risks, as highlighted by a 2019 study on the Cocos (Keeling) Islands. Over half a million hermit crabs on these remote Australian islands were found trapped in items like bottles, resulting in significant mortality. The researchers attributed the issue to the vast amount of trash washing ashore.
Unlike most crabs, hermit crabs have soft bodies and rely on seashells for protection. The influx of human-generated trash in the oceans could potentially lead to a new evolutionary trajectory for hermit crabs, raising questions about the ecological and evolutionary impact of artificial shells in the Anthropocene era.
Stay tuned for further insights into this evolving aspect of marine life and its potential implications on the hermit crab population.
