https://news.yahoo.com/hermit-crabs-dying-mistaking-plastic-235900747.html
Hermit crabs dying after mistaking plastic for shells, study finds, The Telegraph, Dec 4, 2019

Hermit crabs are mistaking plastic for shells and the problem has killed more than half a million of the crustaceans, a new study by the Natural History Museum has found.

The creatures do not make their own shells but instead move from discarded shell to discarded shell as they grow. They are not used to plastic in their environment so do not know to avoid it.

Once they crawl into a piece of plastic debris, the crabs frequently get stuck and starve to death.

The team carried out several surveys across a range of sites to ascertain of how many containers there were, including how many were open, how many were in a position likely to trap crabs, and how many contained trapped crabs.

The results recorded 61,000 crabs trapped in debris on Henderson Island and 508,000 on the Cocos (Keeling) islands. This equated to 1-2 crabs per m2 of beach falling foul of debris, a significant percentage of the population.