Thursday, 3 March 2011

Here be dragons

When seen under a binocular microscope it is clear that centipedes are fearsome predators, well armoured and with huge poisonous fangs. They are a group of invertebrates that I have taken an increased interest in lately because we are attempting to draw up a more complete list of the species to be found in the grounds of the Nunnery at Thetford, home to the offices of the BTO.

This list is something that we have been thinking about for a number of years and, thanks to an opportunity provided by one of our more competitive colleagues, it is something that we now how sufficient interest and momentum to deliver. There has always been light-hearted and competitive banter between staff at the BTO and those at the RSPB headquarters in Bedfordshire. The two sites have similarly long bird lists and it was this that prompted a challenge – which organisation could record the greatest number of different bird species on their headquarters site in 2011. It was easy enough to convince such competitive types of the value of extending the challenge across all taxa!

So here I am, extending my knowledge of centipedes by slowly working through identification keys and by counting legs and claws, working out the shape of microscope pits and by looking for projections on different body segments. I am sure that you would be able to describe a centipede; an elongated body of multiple segments, each with its own pair of legs. More flattened in shape and with fewer legs than a millipede, you’d recognise one without too much difficult. There is some variation around this basic structure, those that live in the soil tending to be smaller, more cylindrical, often blind and with more pairs of legs; those that are surface active with fewer legs and larger heads. Such differences allow you to get down to the family and then genus fairly readily but identifying the species can be more problematic. It is here that the microscope becomes an essential tool.

It is when you view any invertebrate under a microscope (or with a hand lens) that you really come to appreciate them. Features invisible to the naked eye take on magnificent solidity under the lens and you start to realise just how impressive (or perhaps terrifying) many of these creatures would be if they were scaled up to the size of a small dog or bigger. While many beetles and bugs would appear as benign and lumbering herbivores, the centipedes would be terrifyingly fast and efficient predators, chasing down prey and delivering a dose of immobilising venom. Some might consider it a good thing that our planet’s climate cannot support such large and fearsome versions of these familiar species.

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