Asterias forbesi from South Carolina via http://wbtw.com/2015/02/10/1000s-of-starfish-wash-ashore-on-sc-island/
So, for whatever reason, I've been noticing an uptick in the number of reports (and questions from the public) about moribund or otherwise dead starfishes (aka sea stars) being washed up on beaches en masse.
And I've seen a host of different reports. Many from the southeast coast of the United States, in the United Kingdom and even from Cape Town, South Africa.
I thought I would take a moment to provide what seems to be the MOST likely explanation: During storms, violent or strong water currents pick starfish up off soft sediment bottoms and wash them ashore.
Different species of starfish in different parts of the world are affected but all share certain commonalities.
- In almost EVERY instance that this has been reported, there have been reports of either storms or high winds. Even if this was not necessarily reported in the news report itself. For example in the case of the Queensland Pentaceraster case, there was a reported storm involving hail the day before!(here)
- Bear in mind that storms don't JUST mean high winds and rough water current. It also means FRESH WATER input. Echinoderms are notoriously intolerant of low salinity/freshwater. Low salinity water might serve to weaken or otherwise just disable enough of them to be washed ashore.
- The species in question: Luidia clathrata, Pentaceraster sp., Asterias forbesi, Asterias rubens etc. (and others) are all known to occur on sandy or unconsolidated (i.e. loose sand) sediment bottoms. So its not unreasonable to see how strong water currents associated with inclement weather could serve to pick them up and drop them ashore. These species all tend to occur with rather high abundance so they tend to end up washed ashore in great numbers.