Tuesday 31 October 2017

Dozens of Octopus crawl up Welsh beach.

Dozens of Octopus have been sighted crawling up a beach near New Quay in Ceredigion, Mid Wales, over the weekend Friday 27-Sunday 29 October 2017.  Up to 25 Curled Octopus, Eledone cirrhosa, were seen each night on Harbour Beach. Some local residents have attempting to help the animals back into the sea, despite which several dead Octopus have been found on the beach in the mornings. The National Marine Aquarium in Plymouth has also received reports of Octopus strandings on other beaches in Wales as well as the north coast of Devon this week.

A Curled Octopus on Harbour Beach, Ceredigion, on 27 October 2017. SeaMôr Dolphin Watching Boat Trips.

The cause of this behaviour is not clear, as it is not something that Octopus usually do. Mass strandings of Fish are more common, as Fish will sometimes attempt to escape a deteriorating environment by crossing land, a good way of getting out of shrinking ponds or tidal pools. Octopus, at first sight, are less suited to such activity, as they lack the rigid skeletons and water-tight skin of Bony Fish. However, as many Fishermen have discovered, an Octopus left in a bucket on land or a boat is likely to escape very quickly. Exactly what the Octopus might be  trying to escape from is also uncertain. Marine organisms leaving the water usually do it because they have become trapped in a smaller body of water, such as a tidal pool, where the water chemistry can change quickly, for example by the oxygen becoming depleted, or evaporation raising the salinity level, but this unlikely to be the case in the open ocean. Brett Stones of SeaMôr Dolphin Watching Boat Trips has suggested that the Octopus may have been attempting to escape from Dolphins, which have been seen in Cardigan Bay this week and which are significant predators of Octopus.

See also...

http://sciencythoughts.blogspot.co.uk/2016/12/brooding-behaviour-in-deep-sea.htmlhttp://sciencythoughts.blogspot.co.uk/2016/05/dramatic-rise-in-cephalopod-populations.html
http://sciencythoughts.blogspot.co.uk/2015/12/determining-environments-favored-by.htmlhttp://sciencythoughts.blogspot.co.uk/2014/08/brooding-behaviour-in-deep-sea-octopus.html
http://sciencythoughts.blogspot.co.uk/2014/05/egg-masses-of-diamond-shaped-squid-in.html
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