Pond educational resource pack - pond animal identification

CORNWALL

Pond animal identification

Of all the adaptations to life in fresh water displayed by the animals in the following account, perhaps the most interesting are those which allow creatures to breathe under water. Some have evolved ingenious ways of collecting air at the water’s surface and carrying it down with them into the water. The simplest method of breathing under water is simply to allow oxygen to pass through the body surface. This provides an adequate oxygen supply in very small and thin-walled creatures, and supplements the supply in many others.

In some species a layer of oxygen is maintained around the body, forming a "physical gill”. As oxygen is drawn from the gill into the body, more oxygen diffuses into the gill from the water to replace it.

Some animals possess proper gills, which are the aquatic equivalent of the lungs used by many land creatures - structures richly supplied with blood and with a very large surface area for gas exchange.

The animals living in rivers and streams face extra problems posed by the water’s flow. As in the plant kingdom, many species with no particular adaptations to flowing water can nevertheless inhabit rivers and streams in parts where the flow is slowest. The rivers and streams section descibes only species with adaptations to cope with flow.

River and stream

Invertebrates

Lakes and ponds

Cornwall Biodiversity Initiative
Pond Educational Resource Pack
Key Stages 1 & 2

Cornwall Wildlife Trust
Five Acres, Allet, Truro, Cornwall, TR4 9DJ
Tel: (01872) 273939 Fax: (01872) 225476
Registered Charity Number - 214929

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