False Behaviour

False Behaviour

The next level of deception in animals concerns the utilisation of false behaviour. Behaviour that conceals the true nature of the animals’ intentions. Such a predator acting in such a way that it hides it predatory nature around possible prey. These behaviours are more examples of aggressive mimicry as seen in the last blog.

Stenolemus bituberus (assassin bug) deceive spiders into thinking they are the prey rather than the predator. They hunt web-building spiders by plucking the silk of the web, generating vibrations that lure the spider into striking range. Wignall & Taylor (2010) describe that the assassin bugs mimic enough vibrations within the range of vibrations that are classified as ‘prey’ to the spiders.

Figure 1. Stenolemus bituberus exploring a spider web. Photographer: Anonymous (2005).

False behaviour techniques can also be utilised through the use of automimicry. Automimicry is when animals have one body part that mimics another in order to increase survival during an attack or to hide a predators intentions. Laticuda colubrine (yellow-lipped sea krait) appears to have two heads, however, it has evolved through successful use of automimicry to have a tail that looks and behaves like its head. This species of sea snake will intrude into nests looking for a meal exposing the behind unprotected to the environment. However, its tail looks and behaves like it venomous head deterring any would be predators. This species has combined false behaviour and automimicry in order to greatly increase its chances of survival. However, there are fitness trade-offs for such an advantages trait. Rasmussen & Elmberg (2009) describe that the tail needs to be flattened in order to move through the water but this would lead to the tail looking different to the head. We must remember that evolved traits may prove to be advantageous in one aspect but may hinder a species in another, and this will be explored in the future on this blog.

Figure 2. Laticauda colubrina displaying “both” heads. Photographer: Anonymous (2009).

References

1.     1. Anonymous. (2005). Stenolemus bituberus exploring a spider web. http://bio.mq.edu.au/research/groups/behavbiol/Assassins.html ; retrieved 05/04/2015.

2.     2. Anonymous. (2009). Laticauda colubrina displaying “both” heads. http://www.sciencedaily.com/releases/2009/08/090805201539.htm; retrieved 05/04/2015

1.     3. Rasmussen, A. R., & Elmberg, J. (2009). ‘Head for my tail’: a new hypothesis to explain how venomous sea snakes avoid becoming prey. Marine Ecology. 30, 385-390.

2.     4. Wignall, A. E., & Taylor, P. W. (2010). Assassin bug uses aggressive mimicry to lure spider prey. The Royal Society. http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=3061146.

False Markings utilised for Aggressive Mimicry

This week we will explore the use of false markings utilised by predators for aggressive purposes. We will describe how predators share visual characteristics of a harmless species in order to avoid detection or appear harmless to their prey. The most iconic example of aggressive mimicry is utilised by anglerfish and their method of predation. Anglerfish have long filaments, called the illicium, protruding above their eyes from the middle of the head. At the tip of the illicium is a growth of flesh called the esca. The illicium and esca can be moved and wiggled in all directions, creating the illusion of a prey animal. The smaller fish’s response to the anglerfish’s false markings or signal appears straightforward, as the signals appear to resemble the stimulus the small fish would normally get from its own prey (Wilson, 1937). The anglerfish has evolved to be able to deceive their prey and manipulate what the prey is seeing. Some deep-sea anglerfish have even utilised a symbiosis relationship with bacteria in order to emit light from their escas to attract prey but these will be explored in the future.

Figure 1: Deep sea anglerfish Melanocetus johnsonii. Photographer: Anonymous (2015).

Much like the anglerfish; several snakes, lizards and even a shark have evolved to utilise aggressive mimicry in order to attract prey. The method these animals utilise is called Caudal luring. This is the use of tail movements by the predator to attract prey. Acanthophis antarcticus (death adder) is such a species that utilises caudal luring. The death adder will display caudal movements is such a position that the tip of the tail is right above its head, so close to the mouth that a prey item would almost certainly be within striking range (Hagman et al, 2008).

Figure 2: Death adder Acanthophis antarcticus displaying caudal luring. Photographer: R. Hoser (1989).

Next week we will explore false behaviour and its exploits.

References

Anonymous. (2015). Deep sea anglerfish Melanocetus johnsonii. http://www.montereybayaquarium.org/animal-guide/fishes/deep-sea-anglerfish; retrieved 29/03/2015.

Hagman, M., Phillips, B. L., & Shine, R. (2008). Tails of enticement: caudal luring by an ambush-foraging snake (<i>Acanthophis praelongus</i>, Elapidae). Functional Ecology. 22, 1134-1139

Hoser, R. (1989). Northern death adder Acanthophis antarcticus displaying caudal luring. http://www.smuggled.com/addtax2.htm; retrieved 29/03/2015

Wilson, D.P. (1937). The habits of the angler-fish, Lophius piscatorius L., in the Plymouth Aquarium. J. Mar. Biolog. Assoc. 21,477–497.

Defensive False Markings

False Markings

One of the four levels of deceptions in animals is the utilisation of false markings or mimicry. This week, the blog will focus on the use of defensive mimicry. Defensive mimicry can be utilised to avoid encounters that would be harmful to the animals by deceiving their predators into treating them as something else. As mentioned in the introductory blog, Batesian mimicry is such a form. Batesian mimicry is often when a harmless animal has mimicked a harmful one. Mullerian mimicry is when two or more poisonous species have come to mimic each other’s warning signals in order to avoid a common predator. Examples of these follows.

Papilio polytes Linnaeus (Common Mormon) is a black bodied swallowtail butterfly that is well distributed throughout India. Its wide distribution has been achieved through mimicking distasteful and poisonous butterflies in the same environment. The Common Mormon is a good example of sexual polymorphism and Batesian mimicry as it has three female forms and one male form (V.S & Mathew, 2014). The Common Mormon has mimicked the markings of two other butterflies: the red colouration and wing patterns of Pachliopta aristolochiae Fabricius (Common Rose) and Pachliopta hector Linnaeus (Crimson Rose). The red body, bright colouration and wing patterns indicate to predators that this butterfly is inedible. By mimicking these markings, the Common Mormon has avoided the predators by appearing distasteful.

Figure 1: Common Rose Pachliopta aristolochiae feeding. Photographer: Anonymous (2005).

Figure 2: Common Mormon Papilio polytes feeding. Photographer: Anonymous (2014).

Much like the case above; Limenitis archippus Cramer (Viceroy) has come to mimic the warning signals, such as bright wing colouration and patterns, of Danaus plexippus Linnaeus (Monarch). However, both the Viceroy and Monarch butterflies are as inedible as each other. That Viceroy butterflies are as unpalatable as Monarch butterflies (Ritland & Brower, 1991).

Figure 3: Comparative wing patterns of Viceroy Limenitis archippus & Monarch Danaus plexippus butterflies. Photographer: Anonymous (2014).

Next week we will explore the use of false markings for aggressive purposes.

References:

Anonymous. (2005). Common Rose Pachliopta aristolochiae feeding. en.wikipedia.org; retrieved 21/03/2015.

Anonymous. (2014). Common Mormon Papilio polytes feeding. www.thehindu.com; retrieved 21/03/2015.

Anonymous. (2014). Comparative wing patterns of Viceroy Limenitis archippus & Monarch Danaus plexippus butterflies. www.naturenorth.com; retrieved 21/03/2015.

Ritland, David B. & Brower, Lincoln P. (1991). The viceroy butterfly is not a batesian mimic. Nature 350, 497-498.

V. S, Revathy., & Mathew, George. (2014). Identity, biology and bionomics of the Common Mormon, Papilio polytes Linnaeus (Lepidoptera: Papilionidae). IOSR Journal of Environmental Science, Toxicology and Food Technology. 8, 119-124.

An Introduction

An introduction to mimicry and deception of animals

Introduction

Mimicry and deception of animals is a topic of great interest to evolutionary biologists. Mimicry is when an animal resembles another creature or inanimate object for either defence or to gain other advantages. The mimicking species may behave, sound, smell or look like the creature or object it is duplicating. Deception has evolved under natural selection in conflicts between predator and prey, in competition for food and/or in competitions for reproduction (Bond & Robinson, (1988).

Mitchell & Thompson (1986) acknowledge four levels of deception in animals: false markings on animals, false behaviour, feigned injury and verbal deception. These levels will be further explored in detail in the future but for now a few examples will be given for each.

Batesian mimicry is when a harmless animal has evolved to imitate the appearance of a harmful one such as a harmless red milk snake imitating the appearance of a venomous coral snake.

Figure 1: Comparative photo of a coral snake (right) and a red milk snake (left). Photo sourced from: kingsnake.com

False behaviour can be seen in distraction displays such as the broken-wing display. This occurs when a predator is approaching a nest. The bird will walk away from the nest with a wing hung low, dragging on the ground to appear as an east target. Distracting the predator’s attention away from the nest.

Feigning death is the simple act of “playing dead”. A deception act used as a defensive method of avoiding predation as predators prefer to take live prey.

Figure 2: Opossum feigning death. Photo sourced from: http://en.wikipedia.org/

Verbal deception is the use of your voice or sound to deceive others such as the tufted capuchin monkey utilising false alarms as opportunities to grab extra food.

Each level of mimicry and deception in animals can contain numerous deceptive techniques that can prove to quite effective and examples of these will be explored in detail each week.

References:

Bond, C. F., & Robinson, M. (1988). The evolution of deception. Journal of Nonverbal Behavior. 12, 295-307.

Mitchell, Robert W.; Thompson, Nicholas S. (1986). Deception, Perspectives on Human and Nonhuman Deceit. SUNY Press. pp. 21–29.ISBN 1438413327.