• 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
  15. 15
    15
  16. 16
    16
  17. 17
    17
  18. 18
    18
  19. 19
    19
  20. 20
    20
  21. 21
    21
  22. 22
    22
  23. 23
    23
  24. 24
    24
  25. 25
    25
  26. 26
    26
  27. 27
    27
  28. 28
    28
  29. 29
    29
  30. 30
    30
  31. 31
    31
  32. 32
    32

Investigating the colour variation of Littorina littoralis and their abundance across the upper, middle and lower zones of a rocky shore

Extracts from this document...

Introduction

Abstract The objective of this study was to see whether the abundance of different shell colours of Littorina littoralis were distributed in any significant way over the upper, middle and lower zones of a rocky shore. The study took place on Porth Cwyfan, Wales, and involved taking readings of shell colours over each zone using an interrupted belt transect. Using the chi-squared it was shown that there was significance in how the different shell-coloured Littorina littoralis were distributed. Section 1 - Introduction Littorina littoralis are gastropod molluscs distributed widely in north-west Europe [1]. The species is known colloquially as the 'flat periwinkle', due to its shell's flattened spire. Littorina littoralis exist in a variety of colours, usually appearing olive-green, but yellow, brown, banded and criss-cross patterned varieties are also common [1]. Figure 1.1 shows a selection of Littorina littoralis shell colours. These colours are related to the degree of exposure to wave action, with olive-green shells being dominant on sheltered shores and criss-cross brown shells on exposed shores [1]. These differences are believed to be maintained by visual selection of predators, such as shore fishes [1]. Throughout the day, most coastal areas experience two high tides and two low tides. High tides cause the sea to flood in, submerging the entire rocky shore while low tides expose the shore to harsh winds and extremes in sunlight The exposure to sunlight varies along the rocky shore. The lower zone of the rocky shore is predominantly covered by the sea for most of the day. British shores are particularly muddy-brown in colour, and so the majority of sunlight will be blocked before it can reach the sea bed. The upper zone, however, is exposed to air and sunlight for the majority of the day, only becoming submerged at full tide. Even at full tide, the sea would be very shallow and so significantly more sunlight would reach the sea bed here than in the lower zone. Littorina littoralis live in association with certain fucuoid algae. ...read more.

Middle

Once the samples were finished with, they were returned safely into the same quadrat in which they were found. Table 3.1: The number of Littorina littoralis in the upper zone of the rocky shore Number of individuals found in each 0.25m2 quadrat Colour 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Total Black 0 0 2 0 1 0 0 0 0 0 0 0 0 0 0 3 Yellow 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 2 Green 0 2 1 0 0 1 0 1 0 0 0 0 0 0 0 5 Orange 0 0 0 1 0 0 0 0 0 0 2 0 0 2 0 5 Brown 0 0 0 1 0 0 0 0 1 0 1 0 0 0 0 3 Table 3.2: The number of Littorina littoralis in the middle zone of the rocky shore Number of individuals found in each 0.25m2 quadrat Colour 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Total Black 5 1 0 0 4 2 0 1 0 3 3 1 0 5 0 25 Yellow 2 0 1 0 0 0 0 3 0 0 0 0 0 0 0 6 Green 0 0 0 0 1 7 3 1 1 0 0 0 0 0 1 14 Orange 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 2 Brown 0 0 2 0 1 0 0 0 0 0 1 0 0 0 0 4 Table 3.3: The number of Littorina littoralis in the lower zone of the rocky shore Number of individuals found in each 0.25m2 quadrat Colour 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Total Black 8 8 7 13 8 1 5 2 3 8 5 9 5 4 6 92 Yellow 0 0 0 2 1 2 0 ...read more.

Conclusion

This adaptation to mimic its green surrounding would lead to these being less easily identifiable by predators and so increase their chances of survival. However, in areas with no seaweed cover, this species may appear more contrasting, and hence the reason that the green-shelled Littorina littoralis are not the most dominant shell colour overall. Graph 3.3 shows that the green-shelled Littorina littoralis are joint first in being the most dominant shell colour for the upper zone. The brown-shelled Littorina littoralis are in relatively low numbers compared to the black or green-shelled Littorina littoralis. The brown-shelled Littorina littoralis are actually reddish-brown in colour, meaning they would stand out slightly against a grey rock or green seaweed. Throughout certain areas of the middle zone, there existed dark brown coloured seaweed, which could help the brown-shelled Littorina littoralis appear more camouflaged. In this investigation, I feel an unanswered issue is the natural movement of this species along the shore. It is not known whether some or all Littorina littoralis actively seek out their optimum environment, or whether they are randomly distributed by factors such as wave action. Both of these processes would lead to those Littorina littoralis unsuited to the environment to be found in low numbers there, and those best suited to be found in higher numbers. Further work into this would provide considerable additional evidence to help support this investigation. Although every effort was made make sure that the data collect is valid, this does not mean that the data itself is a true reflection of this species everywhere. The data collected was limited to one particular rocky shore over a period of roughly three hours at one time of the year. I cannot be certain of how the data from this rocky shore is a reflection of all Littorina littoralis. The results for each zone of the rocky shore deviate considerably in places, meaning that I cannot claim their truth to a one hundred per cent certainty. Any conclusions drawn from these results will therefore be a reflection of this variability in data. ...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 Genetics, Evolution & Biodiversity 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 Genetics, Evolution & Biodiversity essays

  1. Marked by a teacher

    An Investigation into the Mitotic Nuclear Division of Allium Sativum Root Tip Cells, and ...

    5 star(s)

    Degrees of Freedom Probability Greater Than 0.1 0.05 0.01 0.001 1 2.71 3.84 6.64 10.83 2 4.60 5.99 9.21 13.82 3 6.25 7.82 11.34 16.27 4 7.78 9.49 13.28 18.46 If X� > P = 0.05 (7.82), the null hypothesis should be rejected.

  2. Peer reviewed

    An Investigation into the effect of caffeine on reaction times

    5 star(s)

    Any improvement could be due to practise instead of caffeine dose. However, it is important that the dose is increased gradually so that they are not given a dose that is too high. I will take this into account when analysing my results.

  1. Peer reviewed

    Is there a relationship between the girth of a tree trunk and the percentage ...

    4 star(s)

    32 28 21 30.75 594 9 1.007 53 36 36 33 39.50 608 10 1.564 62 44 39 37 45.50 710 11 0.893 58 54 31 39 45.50 644 12 1.000 66 49 42 43 50.00 638 13 1.284 50 33 34 37 38.50 104 14 1.796 71 49 43

  2. Investigate how the height to width ratio of Limpets varies with distance from sea

    Therefore shell height is often higher. Limpets reproduce once a year, usually during winter. Limpets are hermaphrodites, maturing as males at 9 months and undergoing sex change after 2 years (8). Rough tides disperse the eggs and sperm, the larvae are suspended in the sea before securing themselves to a hard surface.

  1. Recombinant DNA, genetically engineered DNA prepared in vitro by cutting up DNA molecules and ...

    Thus, knowledge of the way DNA is synthesized has had important effects on biophysical research. (See also Cell.) Chromosome, microscopic, threadlike part of the cell that carries hereditary information in the form of genes; among simple organisms, such as bacteria and cyanobacteria (formerly called blue-green algae), chromosomes consist entirely of

  2. Cell Theory - Discuss the theory that living organisms are composed of cells.

    For every enzyme there is only one shape of substrate that will fit into the enzyme's active site. 2.3.3 Explain the effects of temperature, pH, and substrate concentration on enzyme activity. Increased substrate concentration = increased enzyme activity Moving away from optimal temperature decreases enzyme activity Changing the pH denatures the enzyme 2.3.4 Define denaturation.

  1. An Investigation into the effect of flow rate on the size of Gammarus pulex

    Fast flowing streams of rivers are usually well oxygenated.15 Shrimps require high concentration of dissolved oxygen and therefore have conspicuous respiratory apparatus such as gills. Hypothesis Hypothesis "There will a greater number of adult shrimps present in areas of

  2. What is the relationship between genotype and phenotype?

    However, if subjected to an environment in which he receives inadequate quantities of nutrients and suffers from malnutrition, the individual, despite this potentiality, may only grow to a maximum height of 171cm. From this, the following equation may be constructed: Genotype + Environmental Influence = Phenotype However, before the environment

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