• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
Page
  1. 1
    1
  2. 2
    2
  3. 3
    3
  4. 4
    4
  5. 5
    5
  6. 6
    6
  7. 7
    7
  8. 8
    8
  9. 9
    9
  10. 10
    10
  11. 11
    11
  12. 12
    12
  13. 13
    13
  14. 14
    14

A Comparative Study of the Density of Patella Vulgata (Common Limpets) in the Optimum Niche on an Exposed and Sheltered Rocky Shore.

Extracts from this document...

Introduction

A Comparative Study of the Density of Patella Vulgata (Common Limpets) in the Optimum Niche on an Exposed and Sheltered Rocky Shore Planning: - Aim: - To find out if there is a difference in limpet density on shores receiving different wave action. Introduction: - Patella vulgata (common limpet) is a dome shaped mollusc with no spiralling of the shell. It has a strong muscular foot and secretes a chemical to adhere to the rocks. As it clamps down and settles onto a particular rock, it rotates, and upon death, leaves a scar on the rock. This is called the home scar rock, to which the limpet must return after feeding or it will die. This is because the limpet will only form a vacuum against that particular rock. Figure 1. Patella Vulgata situated on rocks Figure 2. A limpet's foot and mantle They feed mainly at high tide and at night. Sometimes they can be seen grazing during the daytime at low tide, especially on exposed shores and in humid conditions. Limpets feed at night on microscopic algae, making them very important seashore herbivores. They feed by scraping their tongue (radula) across the algae covered rocks. Figure 3. Scanning Electron Micrograph of part of a limpet radula showing rows of teeth, some of which are hardened with iron oxide. 100 �m. When the tide is high, the limpets move about grazing on algae. As the tide drops, they usually return to their resting place. This homing behaviour is evident by looking at distinctive scars. Some limpets have been able to find their "home" when relocated as far as a metre away. They use chemoreceptors to find their way back as they don't have any eyes. The algae prevent themselves from being eaten by limpets by recolonisation. They start to grow on the backs of limpets, and other limpets do not feed off the back of limpets. ...read more.

Middle

I couldn't keep the measuring tape 4m all the way along the shore above the tide because the rocks were jagged and rocky so I tried to keep it as constant as possible. The quadrat also didn't lie flat due to the uneven surfaces, so I tried to count the number of limpets as accurately as possible by envisioning the location of the quadrat had the surface been flat. I used the same measuring tape on both shores as the width of the measuring tape could cover a limpet and therefore affect the limpet density on each shore, but if the same measuring tape is used on both shores, as the same error is present throughout the experimental approach, it is fixed error and is cancelled out. All measuring devices and methods contain fixed error, as well as human error. Using coordinates generated from a calculator on both shores ensures the same area is studied on both shores, so a precise comparison is carried out. Apparatus: - * 25cm2 quadrat because this is the best size relative to the organism's size. * Tape measure to lay out at 4m above sea level to take random samples along it. * Optical level to accurately measure 4m above chart datum. * Meter rule to place the optical level on. * Exposed rocky shore - Castle Beach. Grid reference: SM819050 Location: Follow the coast path Nearest Telephone: Dale Fort Nearest Vehicle Access point: Through vehicle gate by point house Escape Route: Coast Path * Sheltered Rocky Shore - Frenchman's Steps. Grid reference: SM819052 Location: Through the field of Point house and down the steps. Nearest Telephone: Dale fort Field centre Nearest Vehicle access point: Road at the bottom of Point House. Escape Route: At low tide, along the beach to the dale fort Jetty beach. * Animal key to ensure I correctly identify the common limpet, not any other type, or even a different species. ...read more.

Conclusion

The optical level has a certain amount of fixed error in it, which cancels itself out as it was present on both shores. The measuring tape also didn't lie flat at 4m, so I wasn't taking samples always exactly in the optimum niche which may explain why some limpet numbers were low. People walking and stepping on limpets may have caused a few of them to fall off, resulting in lower limpet numbers. I may have misidentified the limpet which is highly unlikely, but still a factor to be considered. I used chart datum to determine the optimum niche, however, this may not be entirely accurate and a reliable source of information. Limitations of the procedure were the number of samples, duration of the project, and no repetition of readings. The number of samples was too low to estimate the total size of limpet population in the optimum niche. The project only lasted half a day, at only one time of the year, so it did not allow for seasonal changes such as mating, fertilisation, predation etc. I also only looked at one type of exposed rocky shore and one type of sheltered rocky shore, which limits our evidence of higher amounts of limpets on exposed rocky shores than sheltered rocky shores. There weren't many anomalies, apart from on the exposed rocky shore, the numbers of limpets got a bit low. This could have been due to the fact the tape measure wasn't lying exactly 4m above sea level, so the samples weren't always taken on the optimum niche. Some samples may have been removed from the rocks due to people walking on the limpets and accidentally knocking them off. There may also have been to much intraspecific competition for biota, thus forcing the limpets to repopulate elsewhere. I think the anomalies did have a serious effect on the conclusion of the statistics, as the calculated result (20) was a lot lower than the critical value (127). This proves the experimental procedure was fairly inaccurate and to improve it the sources of error must be tackled. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Energy, Respiration & the Environment section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Energy, Respiration & the Environment essays

  1. Marked by a teacher

    Effect of nitrate concentration on the growth of Duckweeds

    5 star(s)

    been affected, This is because not as much water entered the plant cells, so in more concentrated solution it would have led to dehydration of the cells. Therefore less growth of fronds takes place. Another major limitation of the experiment was the growth of algae.

  2. Marked by a teacher

    In this study I will investigate the length and width of Fucus Serratus fronds ...

    4 star(s)

    These variables include: * Temperature; to ensure that the same conditions are kept throughout the results will be collected on the same day, around the same time. A short delay between the measuring times ensures that the temperature remains constant and the results are accurate.

  1. Weed study. Dandelions - descrption and characteristics. Investigation to dandelion distribution.

    Due to the dandelions nature of being strong and sturdy. I have assumed that more will be present within the grassland area. (This maybe a part of my prediction). The grassland area is situated at Juniper Hall Field Centre, in Dorking in Surrey.

  2. Discuss the Advantages and Disadvantages of being Ectothermic and Endothermic in the Vertebrates.

    Endotherms have therefore developed another mechanism to prevent overheating, which is also practised by ectotherms - behavioural thermoregulation. But endotherms are unfortunately victims of their own success: because their high insulation, which is so good at maintaining a high body temperature, means that it is also hard to lose heat energy!

  1. Aspects of the Ecology of the Shingle beach at Greatstone

    Middle shore should contain bladder wrack, limpets and periwinkles. The middle shore is submerged for half a day and requires the species it contains to be able withstand low light levels, species often wont be able to withstand desiccation. The upper shore is submerged for short periods and desiccation occurs

  2. Practical Plant Diversity . By studying the morphological characteristics as well as adaptations to ...

    In the slide of diatomaceous earth, we observed that there are mainly pennate diatoms with only small amount of centric diatoms. Therefore, by comparing the three diatom slides and the composition of pennate and centric diatoms in the diatomaceous earth slide, we can surely deduce the origin of the diatomaceous earth is freshwater.

  1. Investigation into how Lichen growth is affected as you move further away from a ...

    Any organic matter burnt off, which accounts for any differences in mass Soil Texture Soil texture charts can be used to assess if the soil is mainly clay, silt or sand. But for this investigation the abiotic factors mentioned above are going to be taken into consideration when making any

  2. Effects of exercise on tidal volume and breathing rate

    These neurones automatically maintain the rhythmic cycle of inspiration and expiration. These neurones can be controlled by higher brain functions and afferent information from the body. Afferent Supply 1. Central chemoreceptor ? these are a group of cells that respond to changes in pH.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work