Starshot, snot and algae that look like dog droppings

ANOTHER LIFE:BLOBS OF RAINBOWED jelly, scattered on the grass. Nothing around to suggest where they came from. Just like frogspawn but absolutely clear: no little black dots of eggs. Starshot, snot, slime, slough, slubber, slutch: folk names have multiplied over the centuries. Something out of the sky, anyway, puzzling people since the 1400s and probably long before.

A Sligo hillwalker, Fran Lynch, and a farmer in Co Laois, Michael Murphy, are the latest to report such encounters, sending photographs that launched my drawing. In Scotland in 2008, jelly sightings were so many that they made television news. Suggestions that the jelly might be an alga or a slime mould prompted the programme’s producers to send samples to scientists, each of whom said no, not one of theirs.

I sought the help of Prof Mike Guiry of Galway, a world-class expert on algae, who similarly disowned the jelly but went off on some online sleuthing of his own. This confirmed, via the curator of amphibians at the Natural History Museum in London, that the jelly is exactly what it looks like: the albumen of frogspawn, but without the nuclei of eggs.

Female frogs wander away from ponds to seek shelter in the autumn, while most of the males sink down to spend winter in the mud. But do females really secrete such large amounts of albumen, so far ahead of egg production, that numbers of hungry herons wish they hadn’t swallowed it so fast and whoop it up again? Most samples, as it happens, have been sent to the Kensington museum in the spring, but exceptionally mild autumns may prompt some widespread and premature secretion. Whoever gets the first photograph of a jelly-whooping heron is certain of celebrity on YouTube.

Guiry, as it happens, has been involved in another, rather more significant question of identification. Last month, Prof Andrew Cooper of the University of Ulster told BBC Northern Ireland of his surprise (to say the least) at spotting a stromatolite colony in a tiny, brackish pool in a corner of the basalt rocks that compose the Giant’s Causeway, on the coast of Co Antrim.

Stromatolites are made by blue-green algae that grow like flaky pastry, enclosing pebbles or other debris that litter their surface and rising in hundreds of wafer-thin layers. As fossils in rocks, dating back more than two billion years, the final, dome-like structures are the oldest known products of cellular life. But blue-green algae in various forms are still alive and well, growing by photosynthesis and still producing stromatolites at rare locations, most famously in shallow, warm and highly saline waters at Shark Bay, in Western Australia, and in South Africa. Some have appeared in television documentaries on the evolution of life on Earth. Cooper knew them from his own work in South Africa.

Essential to their formation is a supply of calcium carbonate for the interleaving layers. At the Giant’s Causeway site, he suggests, rainwater flowing from a nearby bank of seashells has helped to create the initial stromatolite layer.

News of his discovery spread rapidly on the internet and even to an entry on Wikipedia. This recorded his conjecture that stromatolites might not, after all, be so rare, just rarely looked for. But the photograph of the Giant’s Causeway algae on the BBC website appeared, to Dr Guiry, like something else altogether: a mat of a rubbery blue-green algal species of the genus Nostoc. In a wet autumn, this commonly springs up from nowhere on people’s lawns and driveways, and, as Guiry has seen, occurs widely on Irish and British coasts.

He expressed his doubts in an e-mail to Cooper, adding his concern that protection for existing stromatolites might be put at risk by any doubt of their rarity. The University of Ulster professor, in turn, found “no harm in your scepticism” – it was a surprising location in which to find new structures. But he stuck to his guns: “They are most definitely stromatolites.” An equally confident colleague, Dr Joerg Arnscheidt, is collaborating in further investigation.

This month brought several complaints about Nostoc to Eye on Nature: it can be slippery and unsightly and looks a bit like dog droppings when it is dry. Guiry has created an annex for it on his website (seaweed.ie/algae/ Nuisanc_blue_green_algae.html). The alga seems to have a special liking for limestone, he finds, coating not only wet hollows in the pavements of the Burren but even the limestone chippings of institutional flat roofs. (Granite gravel, he suggests, might be a better choice.)

Nostoc commune is the Irish species in question. Another form had me puzzled in Greenland, where it lived submerged in tundra lakes like clusters of dark-green grapes. Whatever its shape, and welcome or not, it’s worth remembering that blue-green algae (cyanobacteria) are what, through photosynthesis, first gave the planet oxygen, a mechanism copied in the plant life that followed. There was enough of it, in time, to support the rest of life.

Eye on nature

Nineteen eighty-six: northbound swallows going through April 9th/10th, chiffchaffs a few days earlier. Local swallows here April 19th/20th. Last outbound swallow October 1st.

Twenty eleven: swallows and chiffchaffs seen March 21st. Local swallows here March 29th. Southbound swallows going through in numbers November 2nd. Eating mushrooms from field November 8th. Climate change?

Ken Ward, Gorey, Co Wexford

Mystery surrounded the origins of a plantation of about 40 oak saplings in a corner of New Ross Golf Club. Mystery solved when a crow was observed plucking an acorn from a nearby oak, carefully digging a hole and burying it.

Jim Sutton, New Ross, Co Wexford

In September I noticed raspberries growing wild on the Luas line at Golden Bridge, in Inchicore.

Stephen Wynne, Dublin

Seeds probably excreted by a bird.

Four years ago a pheasant arrived in our garden and remained there. He is quite tame and comes every day to be fed. How long can a pheasant live? At this stage his colours are not as vivid as they were, and his head is quite grey.

William Byrne, Dundalk, Co Louth

A pheasant can live for up to eight years, but fewer than half of them survive from year to year.

Michael Viney welcomes observations at Thallabawn, Carrowniskey PO, Westport, Co Mayo, or e-mail viney@anu.ie. Please include a postal address