Feigned Injury and Automimicry

This week we will examine another example of feigned injury deception as well as further explain what automimicry is as requested. The following week we will continue to define the different levels of deception and mimicry and in the future really explore the biology behind how species have developed these fascinating traits.

Feigning death is the level of feigned injury; to be able to deceive possible predators (or prey) into believing that they no longer are alive is incredible. The classic case of feigned death can be seen portrayed by Didelphimorphia (the opossums). Ever heard the expression playing dead or playing possum? When Didelphimorphia are threatened or harmed, they will display the appearance and smell as if they are dead. When they are feigning death, the animals lips are drawn back, revealing bared teeth, saliva foams around the mouth and they secrete foul-smelling fluid from their anal glands. This deters possible predators that prefer to take live prey. Thompson et al (1981) describes that the lack of movement in the prey species confers selection benefits by depriving predators of the necessary movement stimulus to launch a final attack. In this case the Opossum utilises feigned death as a defensive mimicry. Next week we will explore the use of feigned death as an aggressive mimicry.

Figure 1: Didelphimorphia playing dead. Photographer: T.Alter (2011).

 Now to take a step back and further explore Automimicry. As stated in my last post, automimicry is where one part of an organism’s body resembles another part. This only occurs within a single species. Chaetodon capistratus (the four-eyed butterfly fish) is such a species that utilises automimicry. It gets its common name from the large dark spots found on the rear portion of both sides of its body. These spots are lined with a bright white colouration creating the illusion that these are its eyes. A vertical bar on its true head runs through its eyes, making it harder to distinguish. Neudecker (1989) states that false eyespots are located in these areas of the body to allow escape and survival following an attack. When threatened they will flee by putting the false eyes in the direction of the predator. Most predators aim for the eyes of their prey, and by placing the false eyes towards the predator, the predator is clueless to the apparent escape attempt that follows.

Figure 2: Chaetodon capistratus displaying its false eyes. Photographer: J.Lyle (2012).

References

Lyle, J. (2012). Chaetodon capistratus displaying its false eyes. http://diver.net/bbs/posts003/87969.shtml; retrieved 19/04/2015

Neudecker, S. (1989). Eye camouflage and false eyespots: chaetodontid responses to predators. Environmental Biology of Fishes. 25, 143-157.

Thompson, R. K. R., Foltin, R. W., Boylan, R. J., Sweet, A., Graves, C. A., & Lowitz, C. E. (1981). Tonic immobility in Japanese quail can reduce the probability of sustained attack by cats. Animal Learning & Behavior. 9, 145-149.

Tony, A. (2011). Didelphimorphia playing dead. http://www.flickr.com/photos/ 78428166@Noo/6289417559/; retrieved 19/04/2015.