The Transitional Zone

The transitional zone, where the taller species give way to more genuinely aquatic ones is well-worth examining in detail. The water here is quite shallow but teems with minute and some not-so-small creatures. From teh bank you should be able to see water beetles swimming about underwater, occasionally rising to the surface for air. There are many different types of water beetle, some plain black and about the size of your finger-nail, others smaller still with various coloured patterns on their wing-cases. (Strangely, water-beetles can fly and can tuck their wings away in the same way as a ladybird). Sometimes water beetles, migrating from one pool to another mistake the glass of greenhoises or motor car windows for water and come to land there often in large numbers. If you are lucky you may see the Great Diving Beetle. This is really big by water-beetle standards, over an inch in length, and can attack, kill and eat small fish. All these water-beetles have a larval stage that is quite unlike the adult. These early stages correspond to the caterpillar stages of the butterfly or moth.

 

flyFlying about among the emergent vegetation you cannot fail to notice the metallic-blue colouring of the Damsel-flies. They, like the water-beetles, spend the early part of their lives underwater, but, of course must leave water when they become adult. There are several different species to be seen along the canal, some predominantly blue, others very dark with a brilliant blue band near the tail, and on occasions slender red ones appear. There is also a difference between the sexes, the males being generally the more strongly coloured. At mating time, some species actually fly through the air while joined together, and if you spend a while watching, you may observe the females dipping their tails in the water to lay their eggs. You may also notice that different species have different egg-laying techniques.

Damsel-flies are the delicate and slow-flying counterpars of Dragon-flies. Some of the Dragon-flies are incredibly fast moving, hawking through the air in search of insect prey. They have strong stout bodies and seldom settle in sunny weather. On slightly overcase days, they are not so active and sometimes land on sedges or lily-pads. Again, there are several different species, some quite large. When they land, Damsel-flies fold their wings, while dragon flies stretch theirs out flat. Despite their threatening appearance, dragon-flies do not constitute a threat to humans and have no sting.

To get a real idea of the diversity of underwater life you must collect and examine material in some kind of container. If you can get or make a pond net, so much the better. You will find many different kinds of water snail, damsel-fly and water-beetle larvae and water beetle adults in your catch. There may be hundreds of slow-moving hoglice (aquatic relations of the woodlice we find in gardens), and with the aid of a magnifying glass the amazing numbers or more minute creatures like Water Mites, Daphnia and wriggling underwater worms.fish