This investigation looked to see whether the height on the shore would affect the size or aperture size of Gibula Umbilicalis. Gibula Umbilicalis are a species of topshell which live on the rocky shore, they can be found in the

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'Investigating the Affect of the Height on the Rocky Shore on the Ratio Length to Aperture of Gibula Umbilicalis Topshells'

Title of Investigation: THE AFFECT OF THE HEIGHT ON THE ROCKY SHORE ON THE RATIO LENGTH TO APERTURE OF GIBULA UMBILICALIS TOPSHELLS

This investigation looked to see whether the height on the shore would affect the size or aperture size of Gibula Umbilicalis. Gibula Umbilicalis are a species of topshell which live on the rocky shore, they can be found in the upper, middle or lower shore and surely must have adapted to live in the upper and middle shore where living conditions are harsher, due to there being less time when the shore is covered by water. As marine creatures they require water to respire, so how do they cope during the time they are out in the air? A preliminary experiment was carried out to choose which heights on the shore would be best to carry out the investigation. A transect with height intervals was used and a count made of the Gibula Umbilicalis at different heights. The two furthest points (i.e highest and lowest) where there was a supply of Gibula Umbilicalis were chosen. A continuous horizontal transect was carried out at these heights and the lengths and aperture size recorded of the topshells found. For each topshell a ratio was made dividing length by aperture diameter. Then a t-test was performed on the two sets of results and showed there was a significant difference between the ratios of the ones in the middle shore and the lower shore. The ones from the middle shore had relatively larger lengths and smaller apertures. From the results it was concluded that the Gibula Umbilicalis in the middle shore had adapted to hold more water, by having a larger shell and lose less of it through the smaller aperture.

Contents

Rationale

Planning

- Hypothesis

- Variables

- Equipment

- Procedure

- Risk assessment

- Preliminary experiment

Implementing

- Choosing heights

- Running mean

Observing and recording

- Results

- Anomalies

Interpreting and evaluating

- Data Processing (t-test)

- Biological principles

- Limitations

Rationale

The rocky shore is full of life with marine creatures and plants that have to adapt to survive harsh conditions and competition. Snails are numerous in number and variation. They have a strong foot muscle which helps them to cling tightly to rocks. This is a useful feature for a creature on the rocky shore as sometimes conditions can be rough, strong waves have great force behind them. However the conditions are subject to change on the rocky shore and some are just as hard on life forms as rough tidal action, for example when the tide goes out organisms that require water will have to do without until the tide comes back in and at points on the shore and times of year this can be a very long time indeed. Snails that require water for living have to adapt to survive for long periods of time without a water supply. The lower shore will be without water for a shorter time than the upper shore, it is easier for species to exist here because of that, but this draws in competition for other things, like food. The upper shore has less competition but species that inhabit this area must adapt to be able to exist without being under water for longer times than they would be in the lower shore. Gibbula umbilicalis is a a topshell snail, they are found across the shore, upper to lower. It would be expected that there is a difference between the Gibbula umbilicalis in the lower shore and the Gibbula umbilicalis in the upper shore. To investigate whether or not this is correct the ratio between the length of the shell and the aperture of the snails could be measured for snails in the upper and lower shores. Gibbula Umbilicalis are a good choice for this investigation as they are easy to find and identify due to their characteristic grey-green shell with purple zigzag pattern, and also the large quantity of them over the rocky shore.

Planning

Hypothesis

I think there will a significant difference in the ratio of topshell length and aperture size between the Gibbula Umbilicalis on the upper shore and the lower shore.

Variables

My independent variable will be the height on the shore. I will carry out a horizontal continuous transect at two heights on the shore, which I will record. I will use my preliminary experiment to decide these heights.

My dependent variable will be the length of the topshell, and the size of it's aperture. I will put these into a ratio of Aperture:Length. Due to the shape of the topshell there is no definite length of shell, but I will measure from the same correlating points (see appendix) for each shell, otherwise the results will not reflect correctly the actual data. The aperture is an oval shape, so I will need to set a standard method of measuring this also (see appendix).
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The variables I will control will be the following:

* The time at which the results are taken will be the same, as It will take me no longer than several hours to collect enough results. Collecting results on different days could make the investigation unreliable.

* The standard method for measuring the length and aperture will be constant

* The Equipment and accuracy to which the results will be measured will be kept the same throughout the investigation

* I will only take shells from one face of the rock i.e. sea-facing or ...

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