I’ve recently attended two courses looking at invertebrates, and focussed on the ultimate ‘creepy crawlers’, millipedes and centipedes; the many legged creatures that derive their names from the Latin for foot, ‘pedis’.
It’s been fascinating looking in detail at these mini-beasts, including poisonous claws and gonopods (genitalia). There is frequent confusion between the two groups, with an assumption that millipedes have many more legs than centipedes. This is true in some cases, but the key differences are that Millipedes have two legs per body segment (hence their classification as Diplopoda), whereas centipedes have only one (Chilopoda). Otherwise there is great variety in leg numbers, even within species, from the fast surface scurrying ‘stone centipedes’ (Lithobius species - see image above) with 15 pairs to long winding ‘earth centipedes’ (Geophilomorpha) with up to 101 pairs. Millipedes include those that roll up into a tight ball (the Pill Millipede, Glomeris marginata) , and the snake millipedes with their numerous legs enabling them to glide over the surface like their namesake and also often curl into snake like spirals when disturbed. All centipedes are carnivorous using their poisonous claws, an adapted leg, to immobilise their prey. In contrast the millipedes are primarily feeders of leaf litter and dead wood, playing an important role in breaking down leaf litter. The millipedes can also be long lived, such as the Pill Millipede which has been recorded as living for 11 years (*).
The best places to find them are under logs & stones and in leaf litter in woods and gardens. I've found all the above types in my garden in the last two days. Just lift up pot or stone and see what’s there – but please don’t forget to place things back to where you moved them from as you may destroy a mini-home and its long-term tenants.
*To identify and read more about these animals and many others that can be found in similar places, try ‘Animals under logs and stones’ by C.Philip Wheater & Helen Read (Naturalist Handbook series, number 22).