How to Identify Plants and Animals on a Shore
Kite Diagrams Showing Zonation Require Accurate Identification
Nov 12, 2008
The plants and animals present on rocky shores in the UK will vary with exposure. Identify the dominant species, draw a kite diagram, and then try to explain the distribution.
Exposure of Rocky Shores
Wave action makes life difficult for the plants and animals that live on the shore. When there are violent storms, or when the rocks are pounded by heavy seas, seaweeds will not be able to remain attached – they will simply be washed away. The same is true for many of the snail-like animals, and anything else that is not firmly attached and ‘armoured’ in some way. Very exposed shores will be dominated by Barnacles and Mussels, both of which attach very firmly (Barnacles with their cement, and Mussels with their byssus threads), and have tough shells.
Plants and Animals Showing Clear Vertical Zonation on Sheltered Shores in the UK
- Brown Seaweeds, especially the ‘Fucoids’ are abundant on sheltered shores, and three or four species can usually be seen as ‘different plants’ – but they will need to be identified accurately. (See ‘Brown Seaweeds’ species information ). Sprial, Toothed, and Bladder Wracks are easy to identify and occupy different parts of the shore, and Knotted and Channel Wracks should also be surveyed when they are found.
- Snail-like Molluscs, particularly the Periwinkles, show vertical zonation very well. Two of the four species commonly found are easy to tell apart – the Small and the Flat Periwinkle – but it can be difficult to distinguish between medium sized Rough and Edible Winkles. (See information about the four common British Periwinkles). The only way to be sure which is which is to look at the angle at which the shell opening meets the main shell – find an obvious (large) Edible Winkle and study the shell opening carefully where it meets the main shell, then look at suspected Rough Winkles. The difference is difficult to explain, but the acute angle of the Rough Winkle (the last millimetre or so) is diagnostic. It is also possible to separate these two species by the pigmentation of their tentacles (Edible is annular and Rough is longitudinally striped) – but they need to be persuaded to show their tentacles, and this is very time consuming!
Kite diagrams are easy to produce once a number of different species have been surveyed, but the explanation for the distribution of animals and plants is a bit more tricky. With the winkles it is useful to consider their breeding strategies, feeding preferences, and tolerance to drying out. With the seaweeds it is a good idea to compare their flotation mechanisms, overall size as well as the rate at which they dry out (laboratory experiments can be designed to compare these drying rates).
