ANIMAL MAGNETISM:CRITTERS OF all kinds find their way into projects submitted for the Young Scientist exhibition, and the selection is as varied as ever this year. Spiders, sea urchins and freshwater limpets have proved ideal for study, writes Dick Ahlstrom
Tomás Carney (13) and Nicky Gray (12), first-year students at St Patrick's Community College in Naas, Co Kildare, focused on house spiders. "We were trying to find out what kinds of spiders we have and what affects them," explained Tomás. In particular, they wanted to look for "jumping" spiders, a variety that likes to pounce on prey rather than chase it down or catch it in a web.
They discovered other common varieties of house spider, including the fearsomely named wolf spider, so named because people thought it hunted in packs.
The jumping arachnid they identified was the zebra spider, which has amazing athletic ability, Nicky said. "The zebra spider has fantastic eyesight and can jump up to 12 times its own size," he said. Its sharp eyesight allows it to land with deadly accuracy, so very little escapes its clutches.
The two conducted a survey to gauge arachnophobia among their peers. They found that two in five of their survey group of males and females admitted fear of spiders. They believe the figure would have been higher, but that some of the males surveyed did not want to admit to it.
Lorna Madden (16), a fifth-year student at Scoil Mhuire in Cork city, chose the purple sea urchin Paracentrotus lividus for her study. She wanted to see whether farmed urchins would pursue prey, and how they responded to presence of unfamiliar predators.
"I was seeing if the sea urchins could sense predators and if they reacted to them; whether it affected their feeding patterns," Lorna explained. The farmed animals might be at particular risk and she wondered whether more "ranched" urchins would survive after placement in the sea if they were "made streetwise" about the dangers.
She found the farmed urchins tended to congregate in tank corners, mimicking wild behaviour by hiding among rocks. Unlike those in the wild, which tended to wait for food to drift by to avoid being eaten by starfish or crabs, the farmed variety went after any available food sources.
She first tested their ability to sense and migrate to food, which they readily accomplished. "If they can sense food they might be able to detect predators," she reasoned, testing this by confining a sea star inside the tank and placing urchin food close by.
The urchins tended to stay away initially but eventually went after the food, suggesting they were aware of a nearby danger, Lorna said. Presence of a predator could therefore influence feeding patterns, she concluded.
She believes that while farmed urchins should probably be exposed to predators, care should be taken when replenishing tank water to choose sea water unlikely to carry traces of predator scent, which could disturb their feeding.
Henry Glass (17), a fifth-year student at Clongowes Wood College, Co Kildare, chose the fresh water limpet, Ancylus fluviatilis, for his study, gauging its distribution in a stretch of the Moneycarragh river in Co Down.
He looked at factors affecting how the limpets orient themselves in the river, and found they follow a "contagious distribution", with clusters of limpets occurring between gaps of low habitation.
Henry found they tended to fix themselves on surfaces parallel to the water flow, and seldom turned sideways to it. They were more frequently found in sunlight but this probably related to the availability of a food supply, algae, which grows more plentifully on surfaces exposed to sunlight.