Join us on February 16th for an enchanting exploration of pond life as it slowly reawakens this February. From the muddy depths to the clear waters, witness the fascinating emergence of aquatic creatures and the gradual revival of vegetation. Discover the intriguing behaviours of mayfly larvae, the stealthy movements of water scorpions, and the vibrant activity of countless other pond inhabitants. Don't miss this captivating journey into the hidden wonders of our ponds, lakes, and rivers. Mark your calendars and dive into nature's underwater marvels!
Article
Pondlife
February sees another slow step in the gradual re-awakening of life in ponds, lakes and rivers. Everything seen last month can be seen this month, except in greater numbers and more often. At first glance most still water now looks clear and empty although many creatures are hiding away in the mud. Most emergent vegetation is in a bedraggled state with even the heads of reedmace at last breaking up. Beneath the surface water lilies are growing quickly, water scorpions are clambering over debris and many mayfly, caddisfly and occasionally dragonfly larvae are active in the muddy ooze. There are a legion of other pond larvae but it is these that tend to get noticed, mayflies because of their three tails, caddisflies because of their cases and dragonflies because of their size and frightening-looking facial mask.
Other large aquatic larvae starting to be seen include those of damselflies, alderflies and diving beetles. Damselfly larvae can be identified by the three leaf-like gills at the end of their abdomens, alderfly larvae by their seven pairs of undulating gills on either side of their body and diving beetle larvae e.g. Dytiscus by their sickle shape, aggressive posture and dangerous-looking curved jaws which are quite capable of inflicting a painful bite. Some of these larvae live one, two perhaps even three years underwater before spending, in many cases, just a few days above it as an adult.
In rivers and streams under and around stones stonefly and blackfly larvae may well be found. Stoneflies can be recognised by their two projecting tails and blackfly larvae by their bulbous bases or tent-like pupae. Other larvae encountered in running water are often spindle-shaped e.g. horsefly and some cranefly larvae which show a preference for muddy areas. A little rarer and more unusual is the larva of the snipe fly which has a sharply pointed head. In stagnant and some polluted ponds the air-breathing rat-tailed maggot of the dronefly with its long, flexible breathing tube is often seen. Before polluted ponds it was quite happy to live in holes in trees where water had collected.
In the water column Daphnia and Cyclops, which can be seen bouncing up and down, are slowly increasing as well as countless algae, protozoa and rotifers. Occasionally an adult whirligig beetle or a water boatman swims across open water. Under stones planarian flatworms are gliding and oligochaete worms wriggling. On the surface, pond skaters and springtails may also be noticed. In ditches large numbers of male water lice Asellus are hanging on to females and along the edges of rivers their close relative the water shrimp Gammarus are scurrying about in equally large numbers. Larger water snails may be seen near the surface in February and possibly pea and orb shells on the surface of the mud. Where there are molluscs there are sure to be leeches feeding upon them.
Although most green algae Chlorophyceae will be noticed later when they bloom or form blanket-weed on the surface of ponds, this is a good time to see single-celled or colonial forms. A microscope is needed to see motile species such as Chlamydomonas and Phacus which seem to move very rapidly using their whip-like flagellae. Euglena is one species that is capable of turning from an animal into a plant and then back again. It is sometimes given away by its strange red eye spot. Many non-mobile green algae have very beautiful shapes e.g. Scenedesmus has curved spines, Pediastrum is star-shaped and Ankistrodermus can either be needle or crescent-shaped. This month the latter species can reach astronomic numbers in the open water of our larger reservoirs. Any filamentous algae noticed are likely to be either Microspora, Oedegonioum or Zygnema.
The most striking of the algae are the desmids and diatoms due to the extraordinary designs and patterns on their silica shells. As yet they are still in small numbers. Desmids are made up of two semi-cells joined together only at one point where their nucleus resides.
The attractive crescent-shaped Closterium tends to get noticed most whereas the lozenge-shaped Mesotaenium, which grows on wet rocks or damp earth, is seen by very few. Diatoms are the undisputed beauties of the algal world due to their amazing designs and fine, intricate markings. Their two silica shells fit together rather like a date box. They will be seen in much greater numbers later, but the bright green star-shaped Stephanodiscus is usually common enough this month.
At this time of year you can occasionally see a scum on the surface of weedy ponds such as Eagle pond on Clapham Common. This is likely to be made up of a vast number of rotifers such as Keratella quadrata trapped in the surface meniscus. Rotifers or wheel animalcules as they were once called are among the most attractive and surprising of all pond creatures. Their attraction is due to their possession of tiny structures which look like minute spinning wheels. These are beating rows of cilia which not only draw food to their mouths but also allow some species to move through the water column twisting, turning and even somersaulting as they do so.
It is their general structure that is so surprising. Although few are more than a millimetre in length with the aid of a microscope you can often see all their internal organs as most are completely transparent. What you see is jaws moving, muscles and intestines contracting, eyespots twitching and even ‘bladders’ evacuating. Not all rotifers are mobile, some creep over mud and others live in mosses and lichens. One group which have a head, trunk and retractile foot prefer to attach themselves harmlessly to other animals such as Daphnia. Around eighty different species are known to inhabit the ponds on Bookham Common including Brachionus which is one of the best for easy viewing of the moving internal organs, Conochilus which is a free-swimming colony that can be seen with the naked eye and Stephanoceros which is regarded by many as being the most beautiful of all.
