Another Life Michael VineyI n the narrow channel at the top of the Irish Sea, where the tide rushes through like a tube train between Fair Head and the Mull of Kintyre, the basalt of Rathlin Island sits on a base of fine-grained chalk, a rock rare in Ireland but surviving here in undersea terraces and the tallest underwater cliffs in these islands. Diving down them, Dr Bernard Picton once wrote: "Is like being on the outside of a skyscraper, with a vertical wall disappearing into blackness below".
Picton is curator of marine invertebrates at the Ulster Museum and a brilliant photographer of their undersea lives (to be wowed by sheer beauty, see www.habitas.org.uk/marinelife). He has spent decades exploring the cliffs and reefs of Rathlin, where an exceptionally rich fabric of rock-hugging animals feed in the plankton-rich currents: soft corals, hydroids, anemones, sea-squirts, sponges - communities that seem to yield up new species all the time. They are one of the many good reasons for Rathlin's protection as a special area of conservation.
The sponges are some of the simplest of seabed life, yet fascinating in all their shape-shifting, multicoloured diversity. As filter-feeding animals, they are particularly useful in early warning of water pollution, and are some of the creatures on the agenda for new sources of pharmaceuticals. Yet their true diversity around these islands has been largely unexplored, not least from lack of experts able to identify or describe them scientifically. With money from an EU "sustainability" fund, a team of research divers led by Picton has just brought Rathlin's roster of sponges up to 128 - almost one-third of all the species known from Ireland and Britain. They include a remarkable 28 species new to science.
That sponges are animals, not plants, may come as a surprise - as it did to early marine science - but even without distinct organs they manage to reproduce by inhaling clouds of sperm, by budding or even from fragments. A famous experiment forced a sponge through a fine mesh, whereupon the cells regrouped and grew into several new sponges.
With amazing plasticity, they adapt to almost anything the ocean likes to throw at them - literally as when, as thin crusts, they are pounded by swells hitting overhanging rocks or the walls of caves. Their shape shifting finds an extreme in a species such as the common, bright yellow Cliona celata. Secreting acid, it bores into limestone or empty oyster shells. It lines a network of tunnels with its own cells, and all that can be seen on the surface of rock or shell are tiny yellow blobs that draw in and expel water, filtering out food particles right down to the size of bacteria.
Given the right conditions, the sponge eventually emerges from rock to become its other forms, most spectacularly a massive, lobed sponge that can be ridged, or develop chimneys, and can reach 100cm across and 50cm high. Great cushions of it ornament the narrows of Ireland's Strangford Lough, where tides surge in and out at dramatic speed.
Most of the new species discovered at Rathlin, however, are the crusting kind, which meant some slow, careful scraping for the museum's subaqua team.
As one of them, Dr Claire Goodwin, explained, this restricted their collection to about eight specimens per dive. The final total was 849 specimens, with most put under the microscope for details of their "spicules" - the internal skeleton, stiffened with silica, that varies from species to species. Some Mediterranean species miss out the silica, which is what gives us the soft, non-scratchy bathroom sponge. Other deep-water invertebrates feature most intriguingly in the new issue of Irish Birds, the excellent research journal of BirdWatch Ireland. Underwater photographs by Nigel Motyer show the bright-orange common starfish and purple-banded dahlia sea anemones wrapped around blue and black-speckled guillemot eggs, lying on a rocky seabed in some 22m of water.
The paper, written with ornithologist Richard Nairn, reports on this scavenging of eggs that had fallen from the guillemots' crowded nesting ledges on cliffs near Doulus Head in Co Kerry. Motyer found the seabed scattered with broken eggs on a series of dives, and once, after a strong overnight wind, with whole eggs. The orange starfish (which usually preys on mussels and other bivalves) were present in swarms, perhaps 1,000 piling on top of each other, five-deep. The anemones would also seize and engulf the eggs in a matter of minutes.
Kerry divers have known about this phenomenon for years, even though it's nowhere in the scientific literature. The starfish and anemones, of course, have probably been at it for thousands of years.
EyeOn Nature
Tits, greenfinches, goldfinches, hedge sparrows, etc, come to my peanut feeder. A flock of long-tailed tits arrive regularly. They have taken a liking to peanuts which I have never encountered in 40 years.
Denis Calvert, Ards Peninsula, Co Down
Winter flocks of long-tailed tits can learn about sources of food by observing the foraging of other birds.
We counted 10 buzzards cruising about over the field next door. They stayed for hours, roosting in a sycamore.
G Taylor, Dromard, Co Down
Similar flocks of buzzards are often reported in Britain, where their population is larger. Perhaps the population has grown so much here that such flocks may become more usual.
In late December I found a large (8.25cm) cream-coloured egg in grass. Could it belong to a whooper swan as we are on their flight path?
Catherine Sutton, Lismore, Co Waterford
The dimensions indicate a goose egg and certainly one out of season. A whooper swan egg averages 11.3cm.