Common Pygmy Woodlouse

 

My species today is a Crustacean:  Trichoniscus pusillus or the common pygmy woodlouse. 

I suspect you just thought "woodlouse" when you saw the picture, but there are apparently 45 species in the UK. This is one of the 'famous five' which make up the vast majority of those we're likely to come across. 

You can perhaps guess from the photo where I found it? Those are annual growth rings on a log from the wood pile. 

So crustaceans are in the same Kingdom as humans: Animalia. Living things are classified into more and more specific groups, until one arrives at species and sub-species. (This business of classification is called 'taxonomy' and it is a classic scientific strategy for getting our heads around stuff.)

Our Kingdom is divided into 35 Phyla and that's where we separate: our friend here in Arthropoda whereas we're in with the Chordata. Crustacea is in fact a sub-phylum of Arthropoda and there's an awful lot of stuff in there besides woodlice. Moving down through the classification system, woodlice are in the Class called Malacostraca (I'd never heard of it until just now either!) which contains all sorts, from huge spider crabs to tiny shrimps. (There are six classes of crustaceans.)

Next down is Order. Woodlice are in the Isopoda order. From what I can gather, they all look like your common-or-garden woodlouse. If you go down to the bottom of the ocean you can find one about half a metre long.

Imagine finding that in your wood pile.