RICHARD COLLINS: The boys opened a can of worms

THE easterly gales of the last few weeks drove millions of marine creatures ashore.

The shells of molluscs and crustaceans were strewn along the tide-line at Malahide. Gulls gathered to feed on the spoils. Whelks, razor-shells and cockles, their bright orange ‘feet’ protruding, were especially abundant.

Tommy Collins, aged five, and his little brother, Liam, on a shell-collecting spree, encountered what seemed to be a giant millipede, alive among the debris. The creature, over a third of a metre long and as thick as a man’s thumb, had hundreds of little legs along its body. On being handled, it burrowed powerfully into the sand.

This was no millipede, however, but a ‘giant’ or ‘king’ ragworm, the largest ‘creepy-crawly’ to be found in Western Europe. The formidable, dark-brown monster with a warty snout, well-known to sea anglers, is one of four rag species in Ireland’s south- and east-coast estuaries. Emerging on the flood tide and retreating to its burrow on the ebb, individuals over a metre long are occasionally recorded. North Wales has particularly large ones. Tommy and Liam, wisely, didn’t handle the beast; it has a pair of pincer teeth that can deliver a painful bite. I’ve been nipped by common red rag-worms, a mere 10 to 12cm long. Their bites are not that painful, but I didn’t test the Malahide giant’s weaponry.

The little ‘legs’, known as polypods, help the rag-worm crawl through mud. They double as ‘lungs’, absorbing oxygen from the water. Without this extra respiration, a ragworm could never grow so large. The water flow they generate draws food items into the burrow, where small creatures and particles of seaweed are eaten. Walk slowly, preferably backwards, on an estuary and you may see a little spout of water suddenly erupting, fountain-like, from a hole in the mud. A ragworm has detected your presence and is burrowing deeply, pushing water from its lair as it does so.

It takes a few years for ragworms to reach full size. Then, one fateful night, the male swims above the mud at high tide, spreading sperm as he goes. Meanwhile, the female bursts open, releasing her eggs. Then, their life’s work done, the expectant parents die.

Natural selection has made us fearful of snake-like creatures. Worms, being long skinny and wriggly, are tarnished with the serpent brush; we don’t warm to their charms. Charles Darwin, however, had the highest regard for them. His last book, The Formation of Vegetable Mould through the Action of Worms with Observations of their Habits, was written when he was 72. Its focus was the ragworm’s distant relative, the earthworm. “It may be doubted,” he wrote, “whether there are many other animals which have played such an important part in the history of the world.” Worms turn over and aerate the soil on which agriculture depends.

Their wriggling, as he impaled them on fish-hooks during childhood fishing expeditions, upset the great naturalist. Back then, Darwin saw a field in which cinders, and various objects, had been dumped. A few years later the debris had sunk beneath the ground.

Darwin’s uncle said that worms were responsible for the transformation; archaeology is indebted to them for preserving its treasures. Their achievements impressed the boy. Decades later, he would measure the extent to which the monoliths of Stonehenge had sunk into the soil through the agency of earthworms.

How was it possible for eyes to evolve by natural selection, creationists objected? Darwin speculated that these organs might have developed from a very primitive, light-sensitive system. For Gáspár Jékely, of the Max Planck Institute for Developmental Biology, the eye of the ragworm larva is exactly that. A living fossil, unchanged for millions of years, it has the simplest eye in the world; a light-sensitive cell and a pigment cell. “Life comes from the sea and the first neurological systems evolved there,” says Jékely. With the humble rag-worm “we come as close as we can possibly get to the evolutionary origin of the eye”.