Do Woodlice prefer damp or dry environments?

Woodlice are commonly mistaken for insects. Although they tend to live in woodland areas, Woodlice closest relatives are actually Crabs, Shrimp and Lobsters, with all 4 belonging to Kingdom Crustacea (www.sylvanusservices.com/resources/woodlice_info.pdf accessed 10/10/14). Crustaceans characteristically live in aquatic or damp habitats. They have cephalothoraxes and lack a water proof exoskeleton (Kent, 2000). Due to their exoskeleton not being waterproof, dry environments are bad for woodlice (Kent, 2000). Water can be lost from their bodies via transpiration leaving them very vulnerable to desiccation (Anselme, 2013).

Their size would indicate that transpiration can occur very quickly, preventing them from venturing very far from their usual damp habitat.

They are terrestrial arthropods but are thought to have evolved from sea dwelling animals such as a Trilobite (www.sylvanusservices.com/resources/woodlice_info.pdf accessed 10/10/14).

Most crustaceans breathe via gills, and therefore need to constantly be close to water sources in order to breathe (Pond, 1990). It can therefore be deduced that woodlice (as crustaceans) need to keep close to water sources in order to survive.

Woodlice are actually nocturnal, emerging at night to feed and socialise (www.sylvanusservices.com/resources/woodlice_info.pdf accessed 10/10/14). They moult throughout their growth, and at the point of the actual moult they are very vulnerable, other woodlice will actively fight over a freshly moulted woodlouse until one wins and consumes it (www.sylvanusservices.com/resources/woodlice_info.pdf accessed 10/10/14).

The purpose of this experiment is to find out if woodlice prefer damp or dry environments. The woodlice will be introduced into choice chambers which are half damp and half dry and allocated a period of time before counting how many have settled in each area. The damp area will be made damp via tap water as woodlice are sensitive to pH (Souty-Grosset et al, 2005).

Anselme, 2013 stated that woodlice seemed to remain immobile in environments that it was deemed to favour. Therefore, this experiment will rely on the woodlice immobilising within a set period of time (10 minutes) before collecting the results.

Woodlice are known as “decomposers” (www.sylvanusservices.com/resources/woodlice_info.pdf accessed 10/10/14). Everything decays and decomposes faster in damp areas, and although there is a lot of evidence that woodlice require the damp to breathe, it may also be possible that they associate damp areas with food sources and so show a preference for damp environments.

The hypothesis is “Woodlice prefer damp to dry environments.”

Materials and Methods

1. 10 Woodlice
2. Choice chamber with gauze
3. Wet and dry kitchen roll
4. Pot to collect woodlice in
5. Stop watch

10 woodlice were located in a nearby woodland area and placed into the collection pot ready to transport.

The choice chamber was then set up. Using the divided areas of the choice chamber, half the chamber was filled with damp kitchen roll and the other half with dry kitchen roll. The gauze was then placed on top of the kitchen roll and finally the lid was put on the top. The 10 woodlice were subsequently introduced to the middle of the choice chamber.

They were then timed and observed for 10 minutes before being counted in their final locations.

This experiment was then repeated under exactly the same conditions and more results were collected.

A control experiment was then performed to ensure that the woodlice were not influenced by other factors when choosing their area to settle within the choice chamber.

Results

In the first experiment, after the allocated 10 minutes, 1 woodlouse became still in the dry area, the remaining 9 settled in the damp area.

In the second experiment 2, after the allocated 10 minutes, 2 woodlice settled in the dry area and 8 were found in the damp area.

In the control experiment, the sample woodlice were allocated the same 10 minutes in order to chose where to settle. 6 woodlice stopped in one half of the choice chamber and 4 in the other.

Discussion

The results are quite clear; the majority of the sample woodlice chose to reside in the damp area of the choice chamber in both experiment one and experiment two. The control experiment showed that the woodlice preference was purely based on the variables of the experiment.

It is possible that less woodlice went to the damp side in the second experiment due to becoming saturated with water so sought out dryer areas to “dry out” (www.sylvanusservices.com/resources/woodlice_info.pdf accessed 10/10/14). To avoid this affecting the results, the woodlice could have been given more time between experiments.

It was unclear whether the woodlice sample contained different species, and woodlice ability to survive for longer in dryer areas depends on the amount of gills they have (www.sylvanusservices.com/resources/woodlice_info.pdf accessed 10/10/14). The species of the sample was unknown, although after viewing some diagrams, it was suspected to be “Porcellio Scaber” (McGavin, 2000). Further research could compare different species and their preferences of environments.

The woodlice all seemed to settle and become still after around 4 minutes of exploring their new surroundings. Their settling was taken as a sign on their preference of area (Anselme 2013).

Although it did seem the exploration of the choice chamber was random, during experiment 1 a smaller woodlouse actually mounted a larger woodlouse. Its fate was therefore dependent on the choices of its carrier, not its own. This may have affected the validity of the results.

The sample size was very small, which makes the experiments results very limited and therefore a repeat of this experiment would require a larger sample group to collect more varied, accurate results.

The amount of water used to create the damp side was not regulated. In order to keep things the same, the water should have been measured and the exact same amount of paper towel should have been used each time.

The experiment could be repeated several times in order to work out a more accurate average choice of the woodlouse.

The control experiment should have been performed first so there was no chance the sample had associated a side of the choice chamber with a certain variable.

A choice chamber is an effective way of finding preference; however it was not a realistic living environment. Damp and Dry soil could have given more reliable, realistic results as it imitates the environment the sample were found in.

The sample woodlice were all collected from the same area. These woodlice were already living in damp conditions, which was a good indicator as to their preferred habitat. The sample could have been collected from various habitats to prove that given the choice, all woodlice prefer a damper environment.

It can be concluded that, on average, the woodlice sample chose to settle in the damp environment than the dry environment, as was hypothesised.

REFERENCES

ANSELME, P. (2013) Preference for rich, random tactile stimulation in woodlice. Learning and motivation. (44), 326 – 336

BADENHAUSSER, I. SOUTY-GROSSET, C. REYNOLDS, J.D. MOREL, A. (2005) Investigations on the potential of woodlice as bioindicators of grassland habitat quality. European Journal of Soil Biology 41, 109–116

KENT, M. (2000) Advanced Biology. Oxford: Oxford university press. Page 488-489

MCGAVIN, G.C. (2000) Insects, spiders and other terrestrial arthropods. London: Dorling Kindersley ltd. Page 212

POND, C.M. (1990) Biology form and function: Diversity of Organisms. Kent: Hodder and Stoughton. Page 95

Sylvanus – Archaeological, Natural History & Illustration Services[online] Welcome to the Weird and Wonderful World of Woodlice! Norwich. Available from: http://www.sylvanusservices.com/resources/Woodlice_Info.pdf [accessed 10/10/14]

BIBLIOGRAPHY

ANSELME, P. (2013) Preference for rich, random tactile stimulation in woodlice. Learning and motivation. (44), 326 – 336

SPENCER, J.O. and EDNEY, E.B. (1954) The absorption of water by woodlice. Birmingham University:Zoology Department

Sylvanus – Archaeological, Natural History & Illustration Services[online] Welcome to the Weird and Wonderful World of Woodlice! Norwich. Available from: http://www.sylvanusservices.com/resources/Woodlice_Info.pdf [accessed 10/10/14]

POND, C.M. (1990) Biology form and function: Diversity of Organisms. Kent: Hodder and Stoughton. Page 95

McGavin, G.C. (2000) Insects, spiders and other terrestrial arthropods. London: Dorling Kindersley ltd. Page 212

Kent M. (2000) Advanced Biology. Oxford: Oxford university press. Page 488-489