Mimesis

Mimesis 

  

Although I might actually move a little bit away from my topic, today I will enlighten another part of mimicry. The reason I say it is not all about my topic, is because a part of this mimicry I'm going to write about, will also be related to shape and not just color, but since I have already mentioned mimicry related to warning(batesian and mullerian) I find it natural to say a few words about other ways that mimic can help an animal, not just by advertising. So this time I will dive deeper into Mimesis. 

  

Mimesis is actually related to camouflage, but not in the in way we would normally think about it. Camouflage is as earlier mentioned, a way to blend in so no one can spot you, basically you look like the background, or have a way of not getting detected. Whit mimesis you are detectable, just not as the individual or the species you actually are. The thing here is that an animal don't mind being seen, as long as it is not interesting for the observer, meaning, if a predator is after you, you mimic something the predator don't eat. The animal were a disguise, and in this way, it will be camouflaged in a broad sense. It is not necessarily for these animals to be poisonous or anything, they simply look like something that the observer don't pay attention to. 

  

Often animals that do this type of mimicry will resemble something in their environment that also make them blend in, like a stone, leaf, branch etc. This means other animals will see the mimicking animal, but not actually realize what it is looking at. That is why this is actually a kind of camouflage.  

  

A lot of insects do this kind of camouflaging mimicry, and some examples would be: 

  

• Stick insects: Shaped and colored like a stick. You could easily look at it without ever realizing it is a living animal. 
• Mantists: Some can look like flowers, with beautiful colors so no prey would notice it, and the prey would encounter the predator and realize everything when it is to late. 
• Katidyds: Shaped like a leaf with green colors, or they could look like an ant, so predators would leave it alone. 
• Fish, lobster, and other sea-creatures looking like corals, polyps and sea-grass. 

  

In a broad sense, you could look at mimesis as something that covers almost all kinds of mimicry, because it means resembling something, whether this resemblance has to do with color, shape, sounds, if it mimics a living object or not, and also it could include mimicking of behavior and special kinds of advertisement. This would then included batesian and mullerian mimicry, but in most cases mimesis just implies to being something that is not interesting, something that goes unnoticed, and therefor other types of mimicry is not included here, and would rather be grouped or included elsewhere. 

In this short movie you can see a lot of different animals living in the sea pretending it is something else that would not interest the predator, that is if it is preyed upon, or if it is a predator – pretending it is something that is not dangerous.

https://www.youtube.com/watch?v=ZMNfpb87pe8#t=75
viewed 1 March 2014.

Bibliography:

Wang,
L, Liu, Z, Wang, X, Shih,
C,
Zhao, Y, Engel, MS, & Ren, D 2010,
Ancient pinnate leaf mimesis among lacewings,
Proceedings of the National Academy of Sciences of the United States
of America, viewed 27 March 2014, <
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2941307/ >

Puetz, M 2002,

Mimesis,
The University of Chicago, Illinois, US, viewed 27 March 2014, <
http://csmt.uchicago.edu/glossary2004/mimesis.htm
> 

Countershading:

What does an eagle soaring in the sky, a shark dwelling beneath the surface, and a deer out on the fields all have in common? They obviously live in different environments, and they all are shaped very different from each other, and they don't eat the same food... But what they all have, is wish of not being spotted. So why do I bring this up? I have already talked about camouflage. What I want to talk about know is a very special form of camouflage you can find everywhere, it is called countershading, and it is found among many sorts of animals.

If you look at an animal from the sea, like a shark for example, you will notice its colors are dark on its back, and light underneath. A lot of animals share this pattern of gradual color change from dorsal side to ventral side. It might be more abundant in the sea, where penguins, fish, sharks, dolphins and wales display this, but lot of terrestrial species also show this pattern, like birds, ungulates, and a range of other animals.

It is very common, and therefor it must also matter in a way, it must be advantageous somehow. In nature almost nothing is random, and neither is this. There is several reasons for why this has developed among animals at such a high degree, but everything comes down to being spotted.

A lot of animals, as well as humans, rely to some degree of 3D vision. Shadows and different colors and shades, create an image that is easy for us to spot-, we easily sort it out from the background, even if the individual is staying still. Light from above will reach an animal, and create a lighter looking surface area where the sunlight hits, usually at the dorsal side. The lateral sides, where the light don't reaches, will look darker, and a shadow might appear towards the ventral side or at the ground where the animal is standing. This is if you look at an animal from the side(lateral side towards you). Light will make it easier to discover an animal, because of this lively 3D created image. Of course, for an animal which don't want to be spotted, this is a major disadvantage, and nature has encountered this problem. By making the dorsal side darker, and the ventral side lighter, the animal counteract the affect of light. They cancel out the shadings that are created by the sun, and make it look less three dimensional and more flat, and thereby they get harder to detect.

This is to show how it works:

picture from http://en.wikipedia.org/wiki/File:Countershading.jpg viewed 18 march 2014

Another good reason for having light colors ventrally and dark colors dorsally, is because you might be spotted from to different angles, and depending on where the light enters from, the environment looks very different, and therefor the colors also must be different. If a shark close to the surface is spotted from above surface, it will have to look like the dark blue sea beneath it so it won't be spotted. Animals further down in the sea beneath the shark, will look up towards the surface with a light background, and the shark must therefor also display a light color to be less visble. This is in general very common in the sea, regardless if you look at a predator or a herbivore. Also a lot of birds have a light ventral side, so that animals below them don't spot them easily with the light sky as a background, while from above they look dark as the ground under them. Predators like eagles use this so that their prey won't spot them, this makes it easier for them to get close. Their prey on the other hand is safer with this coloration since they are looking like the environment no matter if the predator is flying above , or looking up towards the sky.

Under is a couple of pictures showing different animals with countershading, the metod is the same, although the animals look very different.

Picture:< http://rfotd.tumblr.com/post/2728583939/open-water-sharks-have-a-color-pattern-called > viewed 26 March 2014

Picture:< http://gurneyjourney.blogspot.com.au/2013/01/countershading.html > viewed 26 March 2014

Picture:< http://www.nhptv.org/natureworks/nwep2a.htm > viewed 26 March 2014

Bibliography:

Breed, MD & Moore, J 2011, Animal Behaviour, Elsevier Science Publishing Co Inc, San Diego, United States.

Stevens, M & Merilaita, S 2011, Animal Camouflage : Mechanisms and Function ,Cambridge University Press.

Science and the Sea; Countershading 2011, The University of Texas Marine Science Institute, Port Aransas, Texas.

<http://www.scienceandthesea.org/index.php?option=com_content&task=view&id=358&Itemid=10 >

Mimicry – the batesian way

In the last blog I talked about how some animals have adapted wonderful colors and patterns to warn off predators and advertise their distastefulness. This seems to be the perfect adaption to avoid predation, and it really works well, at least until someone else decides to take advantage of this. There is never a competition without cheaters, and in the animal world the stake is high, it's a matter of life or death, which makes winning very lucrative. So what happens when an animal with no defense mechanism start to mimic an animal which do have a good defense and very distinct color patterns? And why does this happen?

An animal with a good defense mechanism and strong recognizable color patterns (aposematism), will quickly teach a predator to stay away, there is no point in hunting something that is inedible. This is of course very beneficial for the prey. But through time the predator might as well stay away from other species with similar attributes, because the predator find them hard to distinguish from each other, and as a result it will stay away from all similar species. The look-a-like species, doesn't have to be in possession of any defending mechanism at all, it just gets benefits because predators think it is inedible. This means that individuals which best mimic the original species, will be the ones that survive, mate and pass their genes on to the next generation. What we end up with here, is to species who resemble each other, one with defense and one without.

The resemblance doesn't have to be exact, very often the colors are the same, but the patterns just look similar in a broad sense. A predator doesn't take its time to stop and count stripes or dots before attaching. Since it often spots the prey in a long distance, it would be time and energy consuming to move all the way up to the prey just to realize it is the real model of that animal, and then have to give up the hunt, and most animals are not even capable of telling the difference. This means that a predator who have tasted the real model with a defense mechanism, basically would give up everything that looks the same, and find something else.

This all sounds really good, and we might think mimicry is a very good strategy, it gains the defenseless species and doesn't seem to effect the original model. But is this really the case? Unfortunately not. The strategy works well if a predator tastes the original model first, and gets a very bad experience. But that is not always the case. Sometimes the predator might actually eat the mimicking species, and then it will get the impression of it being a very good meal. Instead of learning to stay away, the opposite is achieved, because a predator with a good hunting experience, is more likely to hunt the same kind of prey again. This puts the original model species at more risk, since the predator is not likely to distinguish between similar species, and therefor might try to eat original species as well.

Overall, having species mimic you is not good for your defense advertisement, since this seems to confuse the predator and weakens its perception about the link between color patterns and defense. If a predator sometimes catches a species that tastes good and other times something that is really bad and inedible, the link will be erased. Without any link, all species are very vulnerable, since they are very easily spotted, and this might not go in anyone’s favor. All gets eaten, and the predator will have to use time and energy on prey that is not always good for eating.

To make Batesian mimicry work, it is important that the mimicry species are less abundant compered to the original models, basically the mimicry species should be rare, so that most predators only encounter the ones with defense, and thereby making the aposematism work efficiently. The few individuals that mimic an original species, will then in most cases be protected because they don't encounter predators as often, and when they do, the predator is likely to already have tasted a bad version of it, and will then just stay away.

We humans also encounter mimicking species and the originals from time to time, and it's of importance that we learn which is which. That is because some species can be a real treat to us, while others are harmless. If you can't be sure which one is dangerous and which one is not, then play it safe, stay away.

Which of these do you actually think is the original with highly effective venom?

<http://www.scwildlife.com/pubs/julyaug2008/coralsnake.html>,  viewed 20 March 2014, photography by Steve Bennett

<http://www.wildflorida.com/wildlife/snakes/Scarlet_Kingsnake.php>, viewed 20 March 2014, photography by Alan Cressler.

These butterflies look very similar, but only the Monarch is distasteful.

<http://creationrevolution.com/2011/02/mirror-mirror-on-the-wall/>, viewed 20 march 2014.

Bibliography:

Gullan, PJ & Cranston, PS 2010, The insects: an outline of entomology, Wiley-Blackwell, West Sussex, UK.

Aposematism

Have you noticed how many animals display very bold and colorful patterns on their body? Ever wonder why that is? Animals with strong colors are easily detected, and will therefor also put themselves in a potentially dangerous position of being eaten. So why would they still do it?

Imagine you are in a restaurant, and are about to order food. You can choose among three dishes. First one is familiar to you, you have tasted it before and know it is really good, but the price is also really stiff. The second dish on the menu is something you have never tasted, but it's lower in price than the first one. Last dish is something you really dislike, because it have caused you to vomit in the paste, and made you really sick, but this dish is really cheap. Which are you more likely to choose?

I know what my answer will be. I will pick the food I know is tasteful, although it costs me more money compared to the distasteful food. I might also choose to be a bit brave, and try out some of the food I am unfamiliar with and hope for it to taste good. So why will I not choose the cheapest food? That's easy to answer; If it makes me sick or make me vomit, the food will not be profitable too me at all, and that will be like throwing money, time and energy out the window, I will end up having to buy new food anyway, and being sick is certainly never profitable any day. I know this, therefor I will not choose it no matter how cheap it might be, in the long run it will cost me more money than the expensive food and also a lot of energy.

Animals are not always very far from us humans when it comes to their food preferences, and most animals learn quickly, that's why I use this example, just to put things in perspective. Think about this example when you read further.

Animals with strong colors and patterns are often also animals that display some features that give them a big advantage against predators. Colors will help them being remembered, and not in the good way, at least not for the predator. These features might be that they display distastefulness, or they are poisonous, hard to swallow, or have a good defending mechanism in some other way. Colors are therefor a very serious form of advertising to a predator that they are not a good choice of prey, eating a prey would be more costly than advantageous. Some animals can be very poisonous, like some frogs who display a very powerful coloration. Eating a frog like that could be fatal. Other animals just taste really bad, some can like the monarch butterfly, make birds(or other animals) vomit. Other insects, like the wasp can cause a lot of pain by using stinging as a defense mechanism.

So why would animals evolve something like this? If they are eaten, and the predator only after the meal feel the bad effects, how would it help? Well, for that individual who gets eaten, there will be no comfort, but if all individuals within a specie that is very abundant all show the same color pattern, the specie as one could gain from it. This is because a predator with a very bad experience is likely to avoid that animal in the future, especially if the price it had to pay eating that animal(the cost) was higher than the winning of eating it.

If advertisement is going to succeed, the prey must display some sort of easily recognizable pattern, that the predator will not forget. The predator must be able to draw a line between not profitable and strong colors and patterns. This is why a lot of animals use same warning colors although they might belong to totally different phyla or other classifying groups. Some colors are just more striking, easier to see and remember. Orange, yellow, and especially red is common colors, but others are also used. Not all animals use this strategy, there might be several reasons for that. One is that producing a defense mechanism can be costly, and not all can or have evolved this defense, instead many animals rely on camouflage (mentioned in earlier blog), and hope not to be spotted, which is basically the opposite strategy of aposematism.

To make color/pattern warning more efficient, many species have developed a very similar pattern, or they may use many of the same warning colors. There is a reason why wasps, bees, and bumblebees often have the same striped patterns and colors. This reinforces the message to the predator and says that yellow striped individuals are bad prey. If everybody tastes bad or have a way of defending themselves, the predator will soon learn to stay away from all similar species. When many species look like each other, they will also gain in another way. Less individuals from one specie will get eaten, because either specimen eaten will be enough to teach that predator to stay away from all species looking like that. Like mentioned earlier, there is a cost due to advertise like this, because obviously you are easy to spot, and each predator would have to attack at least on prey to be able to learn, but if a specie is abundant, the learning outcome will gain the specie as a whole group and maybe several species at the same time.

There are some predators that are actually able to overcome the defense mechanism of a prey if they become really specialized. Some frogs will eat insects with poison dangerous for almost all predators, but they can develop a counter strategy where they can metabolize the poison without getting sick. Some can even store and accumulate poison in depots in their own body and use this to avoid being eaten themselves. This is not uncommon in nature, and it shows the fact that there is always a race between prey who try to avoid getting eaten, and the predator who try to find possible preys and ways to digest them.

Snake with strong warning colors, strongly capable of defending itself against predators with venomous bites. Picture from http://www.evodivo.com/research.html viewed 11 march 2014.

Wasp with a unmistakeable and familiar colorful pattern. Most wasps and bees display similar colorations. Picture from http://www.naturephoto-cz.com/wasp-photo-4260.html viewed 11 march 2014.

Like many animals this frog display a strong red color, making it easy to spot, but if you know the true meaning of red, then you stay far away from this fellow. Ever wondered why we humans always use red as warning color (as in traffic lights, signs etc.)? Because we learn from the best (nature).

 Picture from http://www.coloredsixpackrings.com/ viewed 11 march 2014

Bibliography:

Breed, MD & Moore, J 2011, Animal Behaviour, Elsevier Science Publishing Co Inc, San Diego, United States.

Valkonen, J 2011, 'Disruption or aposematism? Significance of dorsal zigzag pattern of European vipers', Evolutionary Ecology, vol.25, no.5, pp. 1047-1063.viewed 5 March 2014, < http://link.springer.com.elibrary.jcu.edu.au/article/10.1007%2Fs10682-011-9463-0 >

Mappes, J, Marples, N, & Endler, JA 2005, 'The complex business of survival by aposematism', Trends in Ecology and Evolution, vol.20, no.11, pp. 598-603. viewed 5 March 2014, < http://www.sciencedirect.com.elibrary.jcu.edu.au/science/article/pii/S0169534705002521?np=y >

Camouflage

Camouflage:

It has infiltrated our human society for years, we have learned to use it for our advantage. The military use it, hunters use it, those who just want to blend in know how to use it; camouflage, when you don't want anyone to see you, you put on clothes that make you look similar to your background. Young people do it sometimes when they don't want to stick out, they all dress in the same mainstream fashion clothes, looking exactly the same, afraid someone will look at them with lifted eyebrows. Hunters want to get as close to there prey as possible, so they can secure next weeks dinner(or just brag about it), therefor they put on clothes with same colors as the forest they walk in. And the army wears clothes with pretty much the same purpose, only difference is they hunt people they obviously are not to fond off(not part of the discussion here). The thing is, this is not something our super human brain have worked out as a brilliant idea to either surprise someone or disappear. This is natures idea, and nature have perfected it for thousands of years. Some animals are so good at disguise themselves, you won't see them until you touch them or step on them.

So why is this a common thing in nature?

To answer that you have to realize what risk and pressure all animals live under. Every day is a fight to survive. Nature contain a lot of species who live togheter in a web of connections, where they fight over resources and mates, and almost all living animals find themselves in a position where someone wants to eat them. They will have to try to find a way to escape, fight of predators or not be spotted. Not being spotted is where the camouflage comes in. Coloration is essential if you would like to mix in with the background, and natural selection has rewarded those animals that during time have been successful with this. An animal with green color (like a grasshopper) is less likely to be spotted in grass habitats compared to a red one. This means the red one is more likely to get eaten, which of course is not very pleasant for that insect, and begging on it's knees is not as efficient as it is in our human world, which means adios amigo and no offspring who can carry its genes on to next generation. The green grasshopper on the other hand, might be able to survive another day or two, and have some lucky offspring.

This leads to the fact that any coloration or pattern that makes you less visible, is an advantage for you and your survival, and often if someone gets a mutation or a set of genes that might improve this coloration, this will be selected for. Changing environments create a pressure on all organism to improve all the time, so they can be a step ahead of everyone else. You also find this among predatores. Predatores need to catch a prey to survive, and the predators with best tactics, speed or other solutions are those who are able to produce offspring. Some predators have developed a tactic where they look like their background, so prey don't notice them. This way they can attack by surprise, either by walking up to they prey, or by waiting patiently in their prey's walking path and attack when they prey is within range.The better camouflage they posses, the more prey they catch. It's an evolutionary race to survive, where everyone would have to improve all the time to survive. Competition, predators and habitats change all the time, which means they can never rest, evolving is inevitable.

We humans think we are smart and good with camouflage; well lock at this guys and see how real professionals do it: If you can spot them at all:)

Here is a gecko on a tree.

Picture link: http://kids.nationalgeographic.com/kids/photos/gallery/animal-camouflage/#/gecko-camouflaged-on-tree-bark-4_24666_600x450.jpg

These guys looks much like the branch they are sitting on. Picture from: http://kids.nationalgeographic.com/kids/photos/gallery/animal-camouflage/#/tawn-frogmouths-myall-tree-3_24669_600x450.jpg

To see this spider you need to get really close and pay attention. Picture from; http://www.instantshift.com/2013/02/26/50-perfect-animal-camouflage-photography/

Bibliography:

Breed, MD & Moore, J 2011, Animal Behaviour, Elsevier Science Publishing Co Inc, San Diego, United States.

Introduction

Animal coloration – a resoult of an evolutionary contest of surviving and reproduce.

Who in this world is not amazed by all the variation you find among animals when it comes to their magnificiant colors and attributes. Their features are a resoult of natural selection happening for decades and decades, where they have adapted patterns and all sorts of abnormalties and varietions of colors to acchieve the two main goals in nature, namely survive and reproduce.

Animals have developed all sorts of tactics to survive, regardless if they are herbivores or predatores, and here I will once a week present a cool animal or a special tactic a group of animals use to survive. All is based upon colors and patterns found in the world of animals.