One of the reasons that ponds are such rich habitats is because they provide a very natural type of habitat that has been around for millions of years. During this time, many species of plants and animals have become well-adapted to the conditions that they provide.
Invertebrates: A good pond might have over 100 of the larger invertebrate species (beetles, dragonflies, snails and caddisflies). Little is known about the number of micro-invertebrate animals that might live in a pond – such as water fleas and rotifers.
Added to this are many wetland invertebrates, particularly beetles, bugs and true flies, which live around the margins of ponds.
Amphibians: All of our native amphibians – frogs, toads and newts, are pond specialists and use these waterbodies as their main breeding habitat. Species, such as the Great Crested Newt and Natterjack Toad, are endangered species, so ponds are particularly important to help support them.
Reptiles: One of our native reptiles, the grass snake, also loves ponds, mainly because frogs are amongst its favourite foods.
Fish: Fish are a natural part of the fauna of some permanent ponds. Deeper ponds often support species such as Rudd, Perch and Pike, and even tiny ponds can support the Three-spined Stickleback.
Wetland plants: Most of Britain’s larger wetland plants (around 400 species) can be found in ponds, and some of the rarest depend more or less exclusively on them. About half of the most threatened wetland plants (e.g., those protected under the Wildlife and Countryside Act) are found in ponds. There have not been studies to find out how many species of the smallest plants and algae are present in ponds, but there are undoubtedly many hundreds.
Birds: The birds most commonly associated with ponds are Mallard, Moorhens and Coots. However, ponds can attract many other species, including Waders, Greenshank and Redshank. Many birds, including Swallows and House Martins, hunt over ponds, picking off insects.
Mammals: Ponds can be an important habitat for wetland mammals, including Water Voles. Even Otters, normally associated with rivers, catch fish and amphibians at ponds. Bats, too, hunt around ponds and drink from them. Larger mammals, such as deer, foxes and badgers, use ponds as a watering hole.
(Freshwater Habitats Trust)