Yeti crabs discovered in Antarctic hydrothermal vent systems

A team of researchers from the University of Southampton have described a new species of Yeti Crab – discovered living in the hydrothermal vent systems of the East Scotia Ridge in the Southern Ocean, Antarctica.

Yeti crabs belong to a group of squat lobsters, known as Kiwaidae (named after Kiwa the Polynesian goddess of shellfish), that thrive in the hot waters surrounding the geothermally heated hydrothermal vents. It is the dominant species at these sites occurring at extremely high densities, exceeding 700 specimens per square metre.

The newly described species Kiwa tyleri is named after world-renowned British deep-sea and polar biologist Professor Paul Tyler from the University of Southampton.  This species is morphologically similar to other members of the Kiwaidae family, with the majority of it’s body covered in dense bristles – known as setae. This gives the crab a furry appearance much like the legendary Yeti or Abominable Snowman, hence the group’s common name.

The overall furry appearance of the yeti crab and a closer look at its setae

The overall furry appearance of the yeti crab and a closer look at its setae

This hairlike setae that covers much of the yeti crabs body, specifically its chelipeds, walking legs and the ventral surface of its cephalothorax, have been shown to host clusters of filamentous chemosynthetic bacteria including epsilon-Proteobacteria, gamma-Proteobacteria and Bacteroidetes 1.  These bacteria are thought to be a nutritional source for the yeti crab. The newfound species is apparently better built for climbing than its kin—since it has shorter and more robust front limbs. K. tyleri is also more stout and compact than its other members of the yeti crab family. This physique likely allows the crustacean to jockey for position on vents’ vertical surfaces.

  What makes this discovery of a new species in the Antarctic significant is that crabs and lobsters show an extremely low species number in polar seas due to water temperatures being too low for them to survive . However, hydrothermal vent systems found in the Southern Ocean present a unique warm-water refuge for Yeti Crabs, who have been found to inhabit the warm water environment of the vent chimney. Waters near East Scotia Ridge are generally just above freezing. However, the liquid spewing out of the vents themselves is superhot, and can exceed 400 degrees Celsius. Because the water cools rapidly away from the vents, K. tyleri has only a tiny, Goldilocks-like space in which it can survive. Too close to the vent and they fry. Too far away and they freeze. The water temperature where K. tyleri were found reaches about 25 degrees Celsius.
The team of researchers also observed that some females were located outside the vent’s habitable zone. They hypothesised that like many other deep-sea species, yeti crab larvae require colder temperatures to develop. This requires the females to make a sacrifice, as the cold takes a visible toll through deteriorating their bodies over time. Female crabs likely breed only once before death.

Dr Sven Thatje from the University of Southampton and lead author on the paper, says:

The Antarctic Yeti Crab is trapped in its warm-water hydrothermal vent site by the cold polar waters of the surrounding deep-sea. The species has adapted to this very limited sized habitat — of a few cubique metres in volume — by living in highly-packed densities and by relying on bacteria they grow on their fur-like setae for nutrition.”

See below for a video of yeti crabs surrounding a thermal vent and the highly packed conditions in which they live.

– JK


Journal Reference:

Sven Thatje , Leigh Marsh, Christopher Nicolai Roterman, Mark N. Mavrogordato, Katrin Linse. Adaptations to Hydrothermal Vent Life in Kiwa tyleri, a New Species of Yeti Crab from the East Scotia Ridge, Antarctica. PLoS One, 2015 DOI: 10.1371/journal.pone.0127621

Additional References: 

1. http://www.ncbi.nlm.nih.gov/pubmed/18564185

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