It's not a green-eyed monster - it's a tiny new hermit crab found off the West Coast

14 July 2017 - 12:12 By Aron Hyman
Close-up of the green-eyed hermit crab, a news species discovered in a tiny area off the South African West Coast.
Close-up of the green-eyed hermit crab, a news species discovered in a tiny area off the South African West Coast.

Scientists have discovered a new green-eyed crustacean off South Africa's West Coast‚ which piggybacks sea anemones for protection.

The green-eyed hermit crab - or Paragiopagurus atkinsonae - was discovered by University of Cape Town alumnus Dr Lara Atkinson in waters of between 199 and 277 meters.

Instead of using the shells of sea snails as protection‚ this crab measuring only 7 cm‚ is safeguarded by sea anemones‚ which build up a “soft‚ polypymass” from sand material‚ which forms a shell-like structure.

“When you hold (the hermit crab)‚ it's just organic material glued together with some sand‚” said Jannes Landschoff‚ a UCT PhD candidate who helped to describe the species.

Landschoff and Dr Rafael Lemaitre‚ from the Smithsonian Institution in the US‚ found that‚ besides their distinct eye colour‚ the males also had much larger right chelipeds (claws).

Landschoff said the crabs start life with a tiny shell‚ where anemones start depositing the sandy material and build a habitat for themselves and the crab.

“As the hermit crab grows‚ its live 'shell'‚ or carcinoecia‚ grows with it‚” he said.

The crab was discovered during a three-week survey conducted by the Department of Agriculture‚ Forestry and Fisheries and the South African Environmental Observation Network in 2013. Details of the discovery have only been revealed this month in the open access journal ZooKeys.

It is thought to be restricted to a “surprisingly” small area “for no obvious reason”.

“The area isn't noticeably biologically or oceanographically distinct‚ but more detailed sampling from the area will tell us more about the habitat conditions‚” said Landschoff.

He said that this might be an indication that there is something unusual about the area and could serve as a caution‚ especially for mining activities.

“Incidents like these are flags for future protection. The bottom line is we know so little about these areas from an ecological point of view. If you're planning a marine protected area‚ you have to know what you're protecting‚” he said.