Wednesday, 28 May 2014

Sea Balls, an unwise choice for egg laying

Among the various odd things found on beaches recently have been numbers of balls of compressed plant fragments. The typical size of the near spherical things is about 8 – 12 cm across. They appear to be composed of interwoven bits of marram grass or fragments of rushes. During the storm surges of last winter the fronts of sand dunes were washed away along with the roots of the grasses and much debris was also mobilised from inundated salt marshes. A likely explanation is that some of this debris became waterlogged and was washed out onto the sea floor. Over time, some was rolled into dense balls by the oscillation of swell waves. 

Yesterday we came across at least a dozen such balls on a stretch of the west coast of Anglesey. Another surprise was that a few of the balls were so dense and waterlogged that they must have stayed put on the seabed long enough for Nursehounds (Scyliorhinus stellaris), otherwise known as Bull Huss, to attach their egg cases to them. A rather unwise choice for a dogfish whose eggs are said to take about 9 months to develop before hatching. 

Blogpost by Ivor Rees, a regular contributor to Natur Cymru.

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