Research project proposal

Avoidance behaviors displayed by Apple Snail Pomacea diffusa when chemical signals from different predators are introduced

Alana Olendorf, Josh Stevens, Doug Ericson

I. Background and Significance

Predator-prey interaction is, in essence, the ongoing genetic battle to overcome the opposition (Dawkins & Krebs, 1979). As one party adapts to effectively interact with the other party, the other must also adapt to account for the change. As a predator population becomes more adapted to hunting the prey species, the prey population will also adapt in response to the selection pressure generated by the predator adaptation (Corcoran and Conner, 2017). These adaptations can come in the form of morphological, physiological, and/or behavioral changes. For the predator, these changes could involve adaptations in the ability to find prey, and eat prey. For prey species, these adaptations could involve detecting and avoiding predators.  

When a predator is detected, snails will alter their behavior in order to avoid the predator. Snails can exhibit a variety of different avoidance behaviors such as climbing, burrowing and foraging (Armajo and Sura, 2012). The avoidance tactic used can vary depending on what species of predator is present. Snails use chemical cues in the water to detect predators. Each predator gives off a different chemical cue which can allow snails to display the appropriate avoidance behaviors (Levri et al., 2017). Chemical signals from turtles tend to make snails bury themselves, however chemical signals from fish will usually cause snails to try and get above the water line (Ueshima, Yusa, 2015). Snails can also “learn” avoidance behaviors if they are conditioned to certain predators as hatchlings. Hatchlings conditioned to a certain species of predator exhibit much higher alarm response when exposed to the same type of predator than when introduced to a new predator (Aizaki and Yusa, 2009) .

II. Objectives, Hypotheses and Predictions

The main objective of this experiment is to determine what predator avoidance behavior Mystery snails display in the presence of Betta fish and crayfish kairomones. Specifically, we want to determine if the snails display different avoidance behaviors depending on the type of predator present. Our hypothesis is that Apple snails, Pomacea diffusa, show predator specific avoidance behavior as a response to chemical signals from the predators. If they do show predator specific avoidance behaviors, then when kairomones from two different predators are introduced to the apple snail environment, the snails will exhibit a respond differently to each signal.  We predict that when water that Betta fish have been living in is introduced, the snails will climb above the water line. We also predict that when water that Crayfish have been living in is introduced to the snails tank, the snails will attempt to bury themselves or hide under something as a response to the chemicals that the crayfish secrete. For each replicate, water in the snail tank will be changed, and kept at room temperature with a constant pH. Our objective is to determine if Pomacea diffusa have different avoidance behavior based on the species of predator that is present.

III. Methods

Set-Up

For this experiment we will obtain six mystery snails from the species Pomacea diffusa and one Betta fish. These snails will most likely be of different ages and sizes. The snails will be kept in a filtered 10 gallon tank with a constant pH and at room temperature. This tank will have space left at the top so the snails have the option to go above the water line. There will also be a shelter available in the form of a flower pot that the snails can go under to hide. The betta fish will be kept in a separate unfiltered tank also at room temperature. The crayfish water will be obtained from another group that is using them for their experiment. The two test tanks will also be filtered so that remains constant. An ethogram will be created in order to create a baseline for the snails behavior without the introduction of any predator signals.  

Experimental Design

To start the experiment, we will move the snails from their “home” tank to one of the test tanks. We will let them acclimate to this new tank for at least an hour with the cage or net in the tank. First we will do 3 trials with nothing but the snails in the new tank. We will record where each individual snail is every 3 minutes for a 30 minute time period. Then we will obtain 3 trials with the empty cage in the tank with the snails using the same process to collect data. Then we will put one crayfish into the tank that all the snails are in. We will let the snails stay in this tank for 30 minutes. We will then remove all of the snails and put them back into their original tank.  We will then repeat this process for the next two days so that we will have 3 replicates. Once we have collected all of our data with the crayfish, we will use our third tank to do our second experiment. In this experiment, we will use a net instead of a cage for the betta fish so we will obtain 3 trials with only the net in the water. Our next step will be to put a betta fish in the net. We will use the same process that we did in the first experiment and obtain 3 replicates with the betta fish.

Statistical Analysis

To analyze our data we will use a Chi squared test. The test will tell us if the behavior of the snail is independent of the introduction of “predator water”. The variables will be based on the location of the snails at 3 minute time increments over 30 minutes.  

IV. References Cited

R. Dawkins, J. R. Krebs (1979). Arms races between and within species. Proc. R. Soc. Lond. B 1979 205 489-511.  DOI: 10.1098/rspb.1979.0081. http://rspb.royalsocietypublishing.org/content/205/1161/489

Corcoran & Conner (2017). Predator counteradaptations: stealth echolocation overcomes insect sonar-jamming and evasive-manoeuvring defences. Animal Behavior (2017) 132, 291-301. https://0-www.sciencedirect.com.ksclib.keene.edu/science/article/pii/S0003347217302671?_rdoc=1&_fmt=high&_origin=gateway&_docanchor=&md5=b8429449ccfc9c30159a5f9aeaa92ffb&ccp=y#bib16

Davidson, A.T. & Dorn, N.J (2017). Life history traits determine the differential vulnerability of native and invasive apple snails (Pomacea spp.) to a shared juvenile-stage predator. Aquatic Ecology (2017) 51(3): 331-341. Retrieved from  https://doi.org/10.1007/s10452-017-9620-9

The apple snail website. Retrieved 2018, from http://applesnail.net/content/ecology.php

Levri, E. P., Landis, S., Smith, B., Colledge, E., Metz, E., & Li, X. (2017). Variation in predator-induced behavioral changes in introduced and native populations of the invasive New Zealand mud snail (Potamopyrgus antipodarum Gray, 1843) (J. Rehage & K. Magellan, Eds.). International Journal of Field Research on Biological Invasionons, 12(4), 499-508.

Liu, S., Yang, Q., He, C., & Yu, X. (2017). The complete mitochondrial genome of Pomacea diffusa (Gastropoda: Ampullariidae). Mitochondrial DNA Part B, 2(2), 491-492. doi:10.1080/23802359.2017.1361348

Ueshima, E., & Yusa, Y. (2014). Antipredator behaviour in response to single or combined predator cues in the apple snail Pomacea canaliculata. Journal of Molluscan Studies, 81(1), 51-57.

doi:10.1093/mollus/eyu057Aizaki, K., &Yusa, Y. (2009). Learned Predator Recognition in a Freshwater Snail, Pomacea Canaliculata. Malacologia, 52(1):21-29. Retrieved from http://www.bioone.org/doi/abs/10.4002/040.052.0102?journalCode=mala

Alexander, Jr., & Covich, A. (1991). Predator Avoidance by the Freshwater Snail Physella virgata in Response to the Crayfish Procambarus simulans. Oecologia, 87(3), 435-442. Retrieved from http://www.jstor.org/stable/4219717

Ueshima, E., Yusa, Y. (2015). Antipredator behaviour in response to single or combined predator cues in the apple snail Pomacea canaliculata. Journal of Molluscan Studies, 81(1):51-57. Retrieved from https://academic.oup.com/mollus/article/81/1/51/2939641

Armajo, B., & Sura, S. (2012). Effects of Predator Chemical Cues on Snail Behavior. Practicum in Field Biology, Salt Lake Community College. Retrieved from https://underc.nd.edu/assets/155095/fullsize/armajo2012.pdf

V. Resources Required

  • 3 Fish Tanks 10 gallon
  • Lab bench space for the fish tanks
  • 6 Mystery snails ($20.00)
  • Betta Fish tank water
  • Snail food (Algae tablets)
  • Place for snail to hide under (Flower pot)
    • 1 for each tank
  • Water from Crayfish tank
  • Cover for tank
  • Snail marker