For the past two summers, we’ve been lucky enough to have swallows nest in our outbuilding and thus observe these fascinating birds almost at arm’s length. Like many other beginner birdwatchers though, for years I struggled to confidently pick a swallow from a swift. And when my children started to ask whether ‘those birds’ were swallows or swifts, I knew it was time to do my research! So what is the difference between a swallow and a swift?

A bite-size answer to the question: How and why do leeches suck your blood?

Leeches are segmented worms belonging to the phylum ‘Annelida’. The majority live in freshwater surroundings, though some species can be found in sea and land environments. Most (but not all) are ‘hematophagous’ or, to put it another way, bloodsuckers! So how - and why - do these vampiric type worms suck your blood?