Where do the animals live in the ditch? - the soil

INTRODUCTION   THE SURFACE   THE WATERPLANTS   THE SOIL

The bottom is the dark lower boundary of ditches and ponds, where the solid ground is not always clearly defined and light often barely penetrates. This is the place where almost all aquatic animals flee to, when danger threatens from above. Some first dart into the aquatic plants; if these are roughly disturbed, they eventually let themselves sink to the bottom. There they find sand, mud, and stones to hide under. Many species never leave the bottom and even go beyond the lower boundary, by burrowing into the sediment. This would not be possible without food, and indeed, it is abundantly present: waste (detritus) and algae form an almost inexhaustible food source for species that filter and sieve the bottom mass. They often possess special respiratory organs to be able to remain continuously below the surface. Other, predatory species hunt these waste processing species.

Ostracods, worms (tubifex), and various (red) mosquito larvae are waste processors in the Detritus layer. They possess filter organs for this purpose, which can be very complex. Perhaps the finest is the filter organ of the rat-tailed larvae (hoverfly species), which thrive excellently in downright filthy environments, provided the water is no deeper than the length of their telescopic breathing tubes. Slightly higher up on the bottom, Lesser boatmen churn up the debris layer with their scoop-shaped forelegs and sift out edible particles using sieve hairs.

The screech beetle and its larva burrow into the bottom and hunt mosquito larvae and small worms, as does the alder fly larva. Some species of dragonfly larvae, such as the broad-bodied dragonfly, lie buried with part of their eyes just above the bottom and use their pincer-shaped lower lip to grasp prey walking or swimming across the bottom. Species that are not distinctly bottom-dwelling animals also search for food there: water beetles scavenge for the mosquito larvae and small worms, as do bream and other fish. Birds such as the mallard and the moorhen can also "eat from the floor" if the water is not too deep - the so-called dabbling of the mallard, during which it appears to be standing on its head.