Rock pools (or tide pools) by the oceans are a fascinating view. They are full of animals and plants and are one of the topics marine biology deals with. When the tide recedes, water remains in the pools, thus giving fragile animals the chance to survive. Some of most common rock pool animals are starfish, crabs, sea urchins, anemones and limpets.
Water and Temperature
Larger and deeper rock pools offer better living conditions to their inhabitants. The reason for this is water level. Each tide washes the pool and is then gone, making smaller and shallower rock pools isolated aquariums with difficult conditions for vulnerable species. The sun heats rock pools during the day, but during the night they cool. Warm water forms above while cool water remains beneath. Naturally, smaller pools warm more than bigger ones. Wind evaporation also affects temperature. Occasional rainfalls cool the water too. Since the fresh water is lighter than salty water, it remains on top, giving the inhabitants a chance to survive at greater depths.
Oxygen, Sediment and Light
Animals need oxygen to breathe. During the day, rock pools' plants produce enough oxygen, but oxygen becomes critical during the night. Most of the animals are inactive at that time, which helps the survival rate, but sometimes this struggle ends in disaster. Moreover, the water in rock pools is murky, thanks to the sediment (mud and sand), which additionally deprives the plants of so much needed light for oxygen generation. If there is too much sand and mud, animals may suffocate.
Anemones make their permanent residence in rock pools. It is known that different species fight for better position within rock pools. To feed, they trap food particles with nematocysts, specialised cells located on all parts of their body. Many sea animals make temporary residence in rock pools. They stay until the danger is gone or until they are stronger to go their way. Some of them are starfish, limpets and sea urchins. Many sorts of crabs are common inhabitants. Depending on the size, depth and living conditions, types of inhabitants vary from pool to pool.
Many people come to bathe in rock pools; others come to study them. Since organisms inhabiting rock pools are highly fragile, even the most careful visitors can cause damage to the inhabitants. To preserve marine life in these difficult living conditions, people are advised to take care, particularly when turning stones to discover what is beneath. Bathing also increases sediment level and chances for inhabitants' suffocation.