Saturday, 11 April 2009


I have a thing for arthropods. I had guessed that you, dear reader, had already grasped that fact, but just to reiterate it, here is the funny tale of just one of Britain’s top tiny pond predators, the common water scorpion.

First, a little taxomony. Water scorpions are insects (ED: no, really Max? Tell us something we don’t know) from the family Hemiptera. A colloquial name for most small insects is a “bug”, but this name is actually the common name for the Hemiptera. Hemiptera are called so because they have two pair of wings, the front of which is very thick and serves as a sort of armour. Hemi= half, ptera=wing. Get it?

As well as the wing thing, bugs are distinguished by having an incomplete life cycle (where the young pass through stages of being nymphs before full adulthood, just like cockroaches, Phasmids, grasshoppers and mantids) and sucking mouthparts. They are known as a “primitive” order because they have an incomplete life cycle, but they still have more than 60,000 species described, more than any other primitive order. They are infact the only inscts to be found in the open ocean (a funny group of water striders, you know, the funny fellows which sit on top of the water in your pond in summer). Some common bugs (other than those mentioned) include: assassin bugs, leaf/stink bugs, backswimmers and leaf-footed bugs.

Water scorpions come from the family Nepidae, which is very similar to the family Belostomatidae, or the giant water bugs. They both fullfill very similar niches in their environment: highly cryptic ambush predators who stalk the upper reaches of ponds, lakes and streams. Both families are always a shade of brown (kinda hard to look like a dead leaf if you are not brown) with large and very stong raptorial front legs. With these they grab onto prey before injecting them with a cocktail of venom and digestive juices, and then sucking out the mush. There are two species of water scorpion in British waters, the common (the short fat fellow) and the stick (the long thin one). I have never seen a stick water scorpion, but the other day I found my first common waterscorpion for about a dozen years.

I am currently wrighting a huge piece of Geology coursework. To avoid it killing me, I try to get out every day if I can. On Friday, I decided to go out to a local garden centre or two to have a look around. Now, thanks to some interesting benefits of competition which I am not going to discuss here, in one place on my route there are two large garden centers right next to each other. In front of the larger one there lie a couple of large ponds. I have never bothered to look at these before, but seeing as I walked right passed one on my way to the other garden centre, I had to take a look. It must have been about 35ft long, 8ft wide, but only 1.5ft deep. There was thick reed growth, but oddly, no other aquatic plants. This made it great for looking into, and in about 3 seconds, I had seen my first newt of the day. A possibly smooth, possibly palmate female. This was followed by about 15 more, so I got bored of looking for newts, and mumbled to myself: “Ooo, this would make prefect water scorpion habitat”. I looked, but to no avail.

Until I moved to a different side of the pond and immediately found one. I was slightly surprised; I have said “Ooo, this would make prefect water scorpion habitat” to myself more times than I can remember, but never seen one, so I thanked the giant water bugs in the sky, and began the tricky process of getting the beggar to walk onto a reed stem so that I could pin it down with another piece and transport it back to the car...

In which I had a plastic bag filled with water and some small snails I had got (for free) from the garden centre. There was nothing for it, I had to take my new fiend home with me in this bag. So I did so.

He is currently sat in a small tub on my desk, and I have managed to persuade him to eat a dead baby cockroach, which bodes well for his future life in captivity. He is living with some small snails and is doing rather well. A handy thing about water scorpions is that they don’t have gills, instead relying on a pair of tubes coming out of their back end to reach up out of the water and breathe. This means they can easily acclimatise to different waters (temperature still remains an issue however) and thus they can settle down in captivity very easily.

What I would really like to have now is a couple of giant water bugs. Forget the inch that my water scorpion is, the larger giant water bugs get to over 4 inches, tha largest even hits 6”, making them easily able to make a meal of newts, fish and very large fat snails. What has this got to do with cryptozoology? Could a giant water bug/water scorpion account for sightings of a huge aggressive preadator that lives in the congo and has been known to take down hippos? Err, no. This story has nothing to do with cryptozoology. But hey, I bet you all learnt something from that tale did you not?

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