If you go down to the water today, you never know what you will find... pond-dipping is a classic for a reason – it's fun for all ages, and even the humblest aquatic minibeast has a story to tell: I once had to enthuse kids all day about the contents of a pond when all we were finding were water fleas and bloodworms – no problem! Bloodworms (the name can refer to either the larvae of the non-biting midge or a true worm) are red because they contain haemoglobin, like the stuff in our blood, enabling them to grab any passing oxygen molecule and so survive in smelly anaerobic mud. Water fleas are actually crustaceans who spend all day kicking food into their mouths and can play a crucial role in keeping water bodies clean – fascinating little things!
But some ponds are more equal than others and I can genuinely say that we had an amazing day's dipping at NWT Thorpe Marshes
earlier this year, which was strictly for the grown-ups, and we kept getting better and better minibeasts. It was like we were playing minibeast top trumps, as soon as someone found a damselfly larve, someone else would trump it with a dragonfly, and so on.
Highlights of the day included:
- A nine/ten-spined stickleback. We didn't count the spines, but we did see that he was male in breeding colours). His famous cousin "spineless Si" is the more frequently occurring three-spined stickleback, whose belly goes red when it's time to impress the ladies (we called them "Red doctors" when I was a lad), but the nine-spindled gentleman is more of a goth – it's any colour you like, as long as it's black.
- A true air-bubble carrying aquatic water spider rather than the usual land-spider-that-has-fallen-in. This character is the only spider in the world to actually live underwater, a trick they achieve by carrying air bubbles down to a "diving bell" submerged in the weeds.
If you visit the site, you can see in dyke near the gates to the ponds and broad little yellow-green blobs, which we think are young freshwater sponges, growing on old sedge stems. And if you turn up on the last Sunday morning of each month, from 10.30am to 12.30pm, you can join in with pond-dipping too! See the NWT events page
for more details. It just goes to show how clean the water at Thorpe Marshes is, and how valuable the site is.
Mark Webster, Project Officer