Hermit crabs are attracted to an additive in plastics, which could mean they mistake pollution for food, according to a new study.
The substance causes the animals to become hyperactive, the University of Hull researchers say.
The team has been studying the combined impact of climate change, plastic and other molecules on marine species.
Looking at waters off the North Yorkshire coast revealed that a plastic additive called oleamide increases their respiration rate in response to low concentrations.
The team found that oleamide can be mistaken for the chemical released by food sources during decomposition, meaning the crabs may travel a distance in search of a meal, only to discover plastic.
But the scientists withdrew information suggesting that the animals were ‘sexually excited’ by the substance.
Oleamide had previously been identified as a major constituent in the sex pheromone of cleaner shrimp – a distant relative of the hermit crab – and could be used for chemical signalling in other species, the researchers say.
One, PhD candidate Paula Schirrmacher, explained: ‘Our study shows that oleamide attracts hermit crabs.
‘Respiration rate increases significantly in response to low concentrations of oleamide, and hermit crabs show a behavioural attraction comparable to their response to a feeding stimulant.
‘Oleamide also has a striking resemblance to oleic acid, a chemical released by arthropods during decomposition.’
She continued: ‘As scavengers, hermit crabs may misidentify oleamide as a food source.
‘This research demonstrates that additive leaching may play a significant role in the attraction of marine life to plastic.’
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The researchers said that plastic additives mimicking marine infochemicals may be a problem for other species and said the odour associated with food needed further investigation.
Ms Schirrmacher’s research, in Robin Hood’s Bay, also examined how hermit crabs detect smells in acidified oceans and found that the creatures were attracted to a chemical cue known as PEA (2-phenylethylamine).
The cue is known to warn mammals and other sea life about predators and its effectiveness may be increased in an acidified ocean, the scientists said.
Researcher Dr Christina Roggatz explained: ‘In short, pH can make or break successful communication in the ocean.’
It follows a landmark study on the climate crisis – branded a ‘code red for humanity’ – which mentioned the threat of increasing acidification of the oceans.
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It also comes with scientists increasingly concerned about the impact of plastic on animals, particularly those who live in the ocean.
The university said another study found that rising sea temperatures, combined with increased plastic pollution, can confuse the breeding cycles of blue mussels and affect reproduction rates.
Research suggested that male blue mussels are affected by increased temperature, while females were sensitive to DEHP – a toxic chemical found in many plastics.
Luana Fiorella Mincarelli, a PhD student, said: ‘It is critically important to understand how plastic additives work on molecular levels, especially on reproductive success.
‘We have found that their toxic effect can be amplified in a climate change scenario.’
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