On a rocky shore there is a marine snail which feeds on algae growing on the roc

Question

On a rocky shore there is a marine snail which feeds on algae growing on the rock surface. Two hypothesis have been proposed to explain its upper distributional limit on the shore. The first hypothesis suggests that water loss from the body when animal is exposed to air during low tide kills the animal and therefore limits of the animal is at the height of the shore where energy balance of the animal is zero, i.e. no surplus energy for growth and reproduction. Describe how you would design an experiment (s) to test which hypothesis is correct. (20 marks)

Explanation / Answer

Many animals and plants live on rocky shores in the area between high and low tide called the intertidal zone. These organisms must be able to cope with problems of not one environment, but two. They are pounded by waves, exposed to extremes of temperature and salinity, and flooded by sea water and exposed to drying air twice every 24 hours. They may be exposed to freshwater during rainfall or flood events. They also have to avoid being eaten by birds, molluscs and crabs at low tide, and by fish and other marine life at high tide.

Several distinct microhabitats exist within rocky shore habitats, each with its own survival challenges for plants and animals living there. Some of these microhabitats have distinct shapes which influence how biota will survive there. Yet other microhabitats have high roughness where the terrain goes up and down, providing plenty of places for animals and plants (and water). The rocky microhabitats may have a different

The tide's rise and fall is one of the main factors affecting life on rocky shores. When the tide falls, plants and animals on rocks are exposed to air. They must develop special adaptations to survive until the tide comes in again.

When high tides aren't very big, plants and animals which live high on the shore may be exposed to air for several days. Organisms which live very low on the shore may only occasionally be exposed to air.

Tides can also act as an energy force over the tidal cycle, such as during tidal ebb or flow when the water is rushing away from or towards the shoreline.

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