Discovering Symbiosis
I NTRODUCTION
About the Authors: Kayla Mathewson is a young, ambitious special education teacher at an elementary school in Lakewood, Colorado. She is a graduate from Indiana University, and she played four years of softball for the Hoosiers. She loves sports and is married to an NFL player who plays for the Denver Broncos. She loves teaching and loves helping others. She is very outgoing and loves camping, dancing, and having fun with family and friends. Austin Heckaman is a teacher of ninth-grade biology students. He obtained his Bachelor’s degree from Indiana University Bloomington. He is passionate about instilling a love of science in his students. He likes to take his bulldog, Baxter, for strolls in the park. An avid outdoorsman, he loves to go fishing and camping in Yellowstone National Park.
Standards: SCI.6.3.1 2010 Describe specific relationships (i.e., predator and prey, consumer and producer, and parasite and host) between organisms and determine whether these relationships are competitive or mutually beneficial. SCI.B.4 2010 - Interdependence Describe the relationship between living and nonliving components of ecosystems and describe how that relationship is in flux due to natural changes and human actions.
About the eBook: This eBook is an overview of biology, and it includes different relationships between animals and/or plants. It is written for a ninth grade biology class that needs to learn these topics and teach them to a sixth-grade special education class. The biology students are learning about relationships between animals (symbiosis, predator-prey, parasite-host). As the sixth graders are learning the basic processes of the same relationships, the freshmen will be given the opportunity to teach them a short lesson on these relationships. Although this eBook was written with a specific class in mind, it could also be used to teach other children about these topics This eBook is under a creative commons license, so it can be used as an open educational resource by other teachers and students.
Overview: All of the animals in the world interact with each other and the things around them (plants, streams, forests) to create what is called an ecosystem. An ecosystem is a place where many different animals live and eat. There are many different types of relationships in an ecosystem, but this eBook focuses mainly on the interactions between animals. You probably already know a lot more about animal relationships than you might think. Take a minute to think of as many relationships between different types of animals as you can. (Hint: Some animals eat other animals and other types of animals help each other.) In this eBook you will read about a few different types of animal relationships. These main types are carnivores, herbivores, and symbiosis. Don’t worry if you don’t already know what these words mean, because by the end of this book you will. There will be images and videos throughout this eBook that will help you understand some of the difficult ideas. There will also be a couple of quiz questions that will help you see if you learned the topic of each chapter.
C HAPTER 1
What is an Animal? Do you know what an animal is? They come in all colors, shapes, and sizes, and there might be more different types of animals than you think. There are lions, deer, squirrels, sharks, grasshoppers, worms, eagles, and even jellyfish. All of these are different types of animals. Look at the next few pages of this eBook to see some different types of animals. Although animals can be very different from each other, they all have some basic things in common. They all create energy by breaking down carbohydrates, respond to things that happen around them, and have babies. Based on this definition can you think of another example of an animal? This type of animal walks on two legs, eats many different types of food, and looks like you and me. That’s right! Humans are a type of animal too.
Animals
Here is a Lion part of the Animal Kingdom.
C HAPTER 2
Carnivores: You have probably seen or heard of animals that eat other animals for food. These animals are called carnivores. The word carnivore can be broken down into “carni” and “vore.” “Carni” means meat and “vore” means eater, so you can use this to remember that carnivores are meat-eaters. Spend a minute thinking of as many types of carnivores as you can. Many carnivores have large bodies and sharp teeth. Lions, tigers, and bears (Oh my!) are probably the first types of carnivores that you would think of, but carnivores can be small too. Weasels, hawks, geckos, and some types of bats are all little meat-eaters.
Here s a Lion eating its prey, which is another animal.
These sharp teeth are called fangs and they help the carnivores rip apart their food. The animals that carnivores eat are often referred to as prey. Carnivores are also called predators, and they are said to have a predator-prey relationship with the animals they eat. Just because an animal is a carnivore, doesn’t mean that nothing else eats it. For example, the harp seal is a carnivore because it eats fish and lobsters. However, harp seals are also prey because they are eaten by killer whales. Although these seals are predators in their relationship with fish, they are prey in their relationship with killer whales. Predators are often very fast and strong to be able to hunt down their prey. What is your favorite type of predator? My favorite predator is the Tyrannosaurus Rex, a type of dinosaur. That’s right, some dinosaurs were predators too! I like the T. Rex because it was very big and fast and it had teeth that were huge! Also, the name Tyrannosaurus Rex means “tyrant lizard king,” which I think is really cool. If you have a favorite predator, you should take some time to research it and learn more about it. If you don’t have a favorite, take some time to find one.
My Favorite predator. A T-Rex
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C HAPTER 3
Herbivores Just as some animals eat other animals for food, there are many animals who eat plants for food. These animals are called herbivores. The word herbivore can be broken down into “herbi” and “vore.” “Herbi” means plant and “vore” means eating, so use this as a way to know that herbivores are plant-eaters. Herbivores usually have flat teeth that are good for mashing up the leaves and grass that they eat. Some herbivores even have multiple stomachs that help them digest their food better. Cows and deer have four stomachs. They eat as much as they can when food is available and store it in their first stomach. Then, when they are full or there is no more food, they spit some of the food back up and chew it again. This is called “chewing their cud.” If you’ve ever seen a cow chewing when there wasn’t food around, it was probably chewing its cud.
I’ve already mentioned cows and deer, but try to think of a few other types of herbivores. Because herbivores eat plants, food is often scarce for them during the winter in colder areas, like Canada and the Northern U.S. Different types of herbivores have developed different methods for staying alive through the winter. Some animals, like groundhogs, hibernate. This means that they eat a ton of food in the fall so that they gain a lot of weight, and then they sleep through the whole winter living off of their body fat. This would not work if we tried it, because we were not made to be able to hibernate, but sometimes I wish I could! Squirrels also have a way to survive the winter. Their main food source is nuts. They eat walnuts, acorns, beechnuts, hickory nuts, and lots of other types of nuts. During the fall, they gather a bunch of nuts and bury them in many places around their home. Then they dig up the nuts in the winter when they are hungry. It’s truly amazing that they are able to find any of the nuts to be able to eat them, but the ones that they forget to dig up grow into trees the next year.
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Because herbivores eat plants, they are often they prey of carnivores. For example, rabbits eat grass, and they are eaten by foxes. In this case the rabbit is the prey and the fox is the predator. Because they are often preyed upon, many herbivores have developed ways to camouflage or outsmart their predators. When an animal camouflages itself, it makes itself harder to find. During the winter, when there is snow on the ground, the snowshoe hare turns white to blend in with surroundings. During the rest of the year, its hair is brown, because white hair would stand out in the summer. This amazing color-changing act is a form a camouflage, because it helps to hide the snowshoe hare from animals that want to eat it.
Camouflage Aminals
Here is a camouflaged animal, very hard to see. If you click the arrow to the right there is another picture of a snowshoe hare.
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Many types of herbivorous (plant-eating) insects have developed bodies that blend into the plants that they eat. For example, many caterpillars are green so that they can blend in with the green leaves that they eat. This form of camouflage helps prevent hungry birds from seeing and eating the caterpillars. I have personal experience with caterpillar camouflage, because I had a garden growing up. We used to grow tomatoes in my garden, and we would often have trouble with tomato worms (a type of caterpillar) eating the tomato plants. My sister and I would spend a long time searching for the tomato worms, so that we could move them to prevent them from destroying the tomatoes. Other herbivorous insects have taken camouflage to a much higher level. If you’ve ever seen a leaf bug or a stick bug, you know what I’m talking about (or maybe you missed them because they are so hard to see). These type of insects have bodies that are shaped and colored like leaves and sticks so that no predators (or people) will be able to find them.
As you have learned, it can be a hard life when you are an herbivore. These animals face many problems, such as not having food in the winter and the threat of being eaten. However, herbivores have found many solutions to these problems that help them stay alive.
Here is a Tomato Worm, also very hard to see when hiding on tomato plants. .
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C HAPTER 4
Symbiosis
Symbiosis Video
Symbiosis is a category of relationships between organisms. An organism is a word for any living thing. It includes animals, plants, and even bacteria, which are tiny living cells that are too small for us to see with our eyes. We cannot simply say that symbiosis occurs between types of animals, because some symbiotic relationships include plants and bacteria. The word symbiosis means “living together� so these types of relationship involve organisms that interact closely with each other. There are four main types of symbiotic relationships: commensalism, mutualism, parasitism and mimicry and camouflage. Commensalism involves two different species (types) of organisms that live together so that one organism benefits, while the other organism is relatively unaffected. Mutualism is similar, but in this class of relationships, both organisms benefit from the interaction between them. Parasitism is a type of relationship in which one organism interacts with another organism in a way that helps the first organism but hurts the second organism. Mimicry and Camouflage are indirect relationships between one animal and another or its environment. These next four sections each cover one of these different classes of symbiotic relationships.
Watch this video to get an overview of three of the main classes of symbiosis.
S ECTION 1
Commensalism This class of symbiosis involves species of organisms that interact so that one of the organisms benefits while the other is neither harmed nor benefitted. Most of the types of commensalism involve one animal that rides around on another. The animal that rides on the other benefits because it gets a free ride, but the other animal does not get any benefit from this interaction. A good example of this type of interaction can be seen in remoras. These fish are a perfect example of animal freeloaders, because they hitch free rides on any type of larger animal they can find. They have a special disk-shaped mouth that helps them attach themselves onto large sharks and sea turtles that can carry them around. They even get free meals, because they can eat the scraps of food that their host (the animal carrying them) leaves behind while eating. Remoras greatly benefit from these relationships, but the host animals are unaffected, because the remoras do not hurt them.
Picture of a Remoras in the Ocean
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Another similar commensalistic relationship exists between barnacles and whales. The barnacles attach themselves to the skin of the whale and live their whole life riding around on the whale. The whale does not even feel the barnacles, but the barnacles benefit from being carried through foodrich waters.
The video that you watched in the overview for the symbiosis chapter also gave the example of a spider hitchhiking a ride on a person as a commensalistic relationship. This is only true as long as the spider does not hurt the host, because then that would be parasitism. Also, this relationship is not as strong as normal symbiotic relationships in which both species interact with each other on an almost daily basis. As we continue with the other classes of symbiosis, I will continue to identify relationships that could be placed in multiple categories.
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S ECTION 2
Mutualism
Boxer Crab
Mutualism is a symbiotic relationship that benefits both of the species involved. Examples of this class of relationships can be very diverse, but they usually involve one animal that gains shelter from the relationship and one animal that gains a food source. The best example of this mutualism that I have found occurs between the boxer crab and sea anemones. The boxer crab gets its name because it carries a sea anemone in each of its claws. This gives the crab the appearance of a boxer wearing gloves. When a predator comes near to the crab and tries to eat it, the crab waves the anemones in the face of the predator to scare it off. The tentacles of the anemone are poisonous and will sting the predator if it gets too close, so the boxer crab usually gets left alone. When the boxer crab is eating, it drops little food particles that the anemones can eat. This relationship between the boxer crab and the anemones is clearly mutualistic because both animals benefit. The crab is protected from being eaten, and the anemones are fed by the crab.
Here is a picture of mutualism, the boxer crab.
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There are many different kinds of mutualism that exist between plants and bacteria, so I will give a general overview of these relationships. Bacteria are tiny organisms that are made up of only one cell. In these mutualistic relationships, the bacteria form colonies (groups of bacteria) on and in the roots of plants. These bacteria help the plants absorb water and minerals from the ground better, which helps the plants grow big and strong. In return, the plants provide sugar for the bacteria. The bacteria use this sugar as their food, and they break it down to make food for themselves. This relationship is beneficial to both organisms, because the plants have better access to the things they need to grow and the bacteria are supplied with food. Bacteria growing on the roots of the plant.
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Another example of mutualism can be seen in the interactions between clownfish and anemones. As I said earlier, anemones have poisonous tentacles that can sting or kill most fish in the ocean, but clownfish are not affected by the poison of the anemones. The clownfish live among the anemones and are safe from basically all predators. Some experts argue that this relationship should be seen as a form of commensalism, because the anemone can live without the clownfish and the clownfish seems to receive all of the benefits from the relationship. However, I agree with other experts who say that this relationship is mutualism. As evidence for their claim, they say that the clownfish can scare away predators and remove parasites from the anemones, thereby providing mutual benefits to both species.
There are many other examples of mutualism in the world, and if this topic interests you, so simple research can find more examples. For instance, here is a video about a two different mutualistic relationships. One of the relationships is between ants and a type of plant and the other is between ants and a caterpillar.
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S ECTION 4
Parasitism Another type of symbiotic relationship involves one species that survives by hurting other species. This class of relationships is known as parasitism. You have probably heard of many different parasites. Some common examples of parasites that affect humans are tapeworms, fleas, ticks, and lice. A parasite is an organism that lives on or inside another organism, called a host. Parasites survive by feeding off of the host animal as food. However, most parasites do not kill their hosts, because then the parasite would also die. This is what separates parasites from predators. Parasites often carry diseases that can kill their hosts, though, such as ticks and Lyme disease.
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The first example of parasitism that I will discuss is that of ticks and their hosts. Ticks are small arachnids that live on the blood of host animals. While some parasites only interact with a single host species, ticks can use many different types of animals as hosts. Basically any mammal can serve as a host for a tick. Ticks wait in tall grass for host animals to walk by. When a host animal brushes through the grass, the tick climbs onto the animal and begins looking for a place to begin feeding. The tick uses its pincers to cut a hole in the host’s skin and begins feeding on its blood. It treats the host’s wound with a chemical that prevents the blood from clotting and stopping the wound from bleeding. The tick interaction is temporary, as it detaches from the host after it finishes feeding. This relationship is parasitic, because the tick uses the host animal’s blood to survive and the host animal can experience negative effects from this interaction.
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Another example of parasitism involves tapeworms and humans. Tapeworm eggs can be eaten by humans in raw pork, beef, and fish. Once they are eaten, these eggs hatch in the intestines of a person and begin to grow. The tapeworm latches on to the wall of the intestine and begins sucking nutrients from the person. People can generally live for years with a tapeworm inside them and not even know it. Once the tapeworm gets to be too big, a person can begin experiencing weight loss and can become sick. Before people knew the negative effects of tapeworms, tapeworm eggs were sold as a dieting pill to help people lose weight. However, today we know that tapeworms can make people sick. This is a parasitic relationship, because parasites suck away the nutrients of the person and the host can become sick from this interaction.
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There is another form of parasitism between wasps and caterpillars. Several types of wasps lay their eggs inside caterpillars. The wasp eggs hatch and begin to grow as larvae inside the caterpillar. The caterpillar continues to eat and grow and the wasp larvae feed off of the nutrients that the caterpillar eats. Eventually the larvae become too big and the caterpillar dies. The larvae get as much food out of the caterpillar as they can, then they emerge and are ready to develop into adult wasps. This may sound like something out of a science fiction movie, but it is a natural relationship in nature. Interactions like these are why so many people think of parasites as nasty and negative. In this case the wasp larvae were the parasites and the caterpillar was the host. This example of parasitism is unusual because the parasite kills the host animal. There are several other types of parasitism, including cuckoo birds, emerald ash borers, and botflies. Hopefully you never have to experience the negative effects of a parasite for yourself.
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S ECTION 5
Mimicry and Camouflage:
Another class of animal relationships that could be described as symbiosis is mimicry. I touched upon this topic in the section on herbivores, but I will cover it more fully here. Mimicry is where one animal develops a body, color scheme, or sound of another animal that helps it survive. Predators can mimic harmless animals so that they can sneak up on their prey. Also, animals that would otherwise be eaten can mimic poisonous or aggressive animals to prevent themselves from being eaten. This class of relationships is generally not listed as a form of symbiosis, because it does not involve a direct interaction between two species. Although the interactions present in mimicry are indirect, I believe that mimicry qualifies as symbiosis. Mimicry is almost a class of commensalism, because it involves one species that uses another’s looks to receive benefits, while the other species is unaffected. Camouflage is similar to mimicry, but in camouflage animals tend to copy the looks of plants, rocks, or soil, rather than other animals.
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A well-known example of mimicry can be found between the coral snake and the king snake. The coral snake is a venomous snake that is colored with bands of red, black, and yellow. Predators who have been bitten by a coral snake will be wary of other snakes that look similar to it. The king snake has bands of the same three colors as the coral snake, but they happen in a different order. It is possible for humans to distinguish the difference between these venomous and nonvenomous cousins, but predators will generally stay away from both species. In this case the mimicry serves to allow the king snake to evade predators.
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Another interesting case of mimicry can be found in the fork-tailed drongo, an African species of bird. This bird mimics the calls and noises that meerkats eat so that it can steal their food. For example the drongo can make the sound that meerkats use to warn each other to hide; this cause the meerkats to dive into their holes, allowing the drongo to eat the food that the meerkats dropped. This example of mimicry is particularly interesting because the drongo mimics the calls of the meerkats, rather than their looks (It would be hard for a bird to look like a meerkat.). A type of mimicry that I learned about in school was between bees, flies, and moths. You all know that bees have black and yellow stripes. Well, so do animals that have tried to eat them. Birds that have been stung by bees will remember their black and yellow markings and learn to stay away from them. Some types of moths and flies use this to their advantage. These insects have developed black and yellow markings that are so similar to that of bees that predators cannot tell the difference. This mimicry prevents these flies and moths from being eaten.
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Since all of the examples of camouflage that I discussed were in the herbivore section, I would like to give some examples of carnivores that use camouflage to sneak up on their prey. The first example is the tiger. It has orange fur with black stripes. You might be wondering how bright orange fur helps a tiger stay hidden, and you would be right that it would not help it hide in the forests of North America. However, a tiger’s natural habitat in Asia contains some areas with tall dry grass that has a similar color to the coat of the tiger. The black stripes on the tiger’s fur help to break up its outline and make it harder to see. Both of these camouflage effects help the tiger sneak up on its prey and be a more successful hunter. Another example of a predator using camouflage is the leaf-tailed gecko. This gecko’s body and tail are shaped and colored like a dead leaf. This creative camouflage, combined with the gecko’s patience in standing still, allow the gecko to wait for prey to land near it, so it can eat the prey. Even if the gecko does need to move, it does so with a twitchy walking style that mimics the movement of leaves blowing in the breeze. This camouflage allows the leaf-tailed gecko to catch lots of food.
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C HAPTER 5
Summary Final Quiz
The relationships between organisms often have something to do with food. After all, without a food source, most organisms cannot survive very long. The descriptions of carnivores and herbivores centers on these animals’ sources of food. Remember that carnivores eat meat and herbivores eat plants. Many of the symbiotic relationships also stem from an organism’s need for food, although some have to do with the need for protection or movement. Hopefully this book was very helpful in informing you about carnivores, herbivores, and symbiosis. The many pictures in this eBook should have provided you with a visual description of the topics that were covered. Please use the sources on our citations page as resources for you to further learn about these interesting scientific topics. Hopefully the book was interesting and informative.
Use this quiz to review the material covered in this eBook.
Humans and Dogs are the best example of mutualistic symbiosis!
C HAPTER 8
Credits Carnivores: http://education.nationalgeographic.com/education/encyclopedia/ carnivore/?ar_a=1 http://kids.nationalgeographic.com/kids/stories/animalsnature/m eat-eating-plants/ Herbivores: http://www.qrg.northwestern.edu/projects/marssim/simhtml/info /whats-a-herbivore.html http://citadel.sjfc.edu/students/naa07113/e-port/Herbivores.html Camouflage and Mimicry: http://forums.sherdog.com/forums/f48/top-10-worlds-best-mimic ry-animals-new-2429169/
Symbiosis: https://www.youtube.com/watch?v=zSmL2F1t81Q http://www.ms-starship.com/sciencenew/symbiosis.htm http://education.nationalgeographic.com/education/activi ty/ecological-relationships/?ar_a=1 Commensalism: http://www.princeton.edu/~achaney/tmve/wiki100k/doc s/Commensalism.html http://facstaff.cbu.edu/~seisen/ExamplesOfCommensalis m.htm http://www.britannica.com/EBchecked/topic/127789/co mmensalism Mutualism: http://www.necsi.edu/projects/evolution/co-evolution/m utualistic/co-evolution_mutualistic.html http://video.nationalgeographic.com/video/ant_caterpilla rsymbiosis http://www.britannica.com/EBchecked/topic/127789/co mmensalism Parasitism: http://necsi.edu/projects/evolution/co-evolution/parasite s/co-evolution_parasite.html http://www.britannica.com/EBchecked/topic/443191/par
Animal A living thing that creates energy for itself by breaking down sugars. Animals come in all sorts of forms.
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Index
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Chapter 3 - What is an animal?
Camouflage A form of symbiosis in which an animal develops the looks of its environment to prevent itself from being eaten or to help it eat other animals. In camouflage the animal can look like anything from plants, to rocks, to sand.
Related Glossary Terms Symbiosis
Index
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Chapter 5 - Herbivore 2
Carnivore An animal that eats other animals for food.
Related Glossary Terms Herbivore, Predator
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Chapter 4 - Carnivores
Commensalism A symbiotic relationship in which one organism benefits from its interaction with another organism, while the second organism is unaffected.
Related Glossary Terms Symbiosis
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Chapter 6 - Symbiosis
Herbivore An animal that eats plants for food.
Related Glossary Terms Carnivore
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Chapter 5 - Herbivores
Mimicry A form of symbiosis in which one animal develops characteristics of another animal to prevent itself from being eaten or to help it eat other animals. In mimicry one animal can look or sound like another animal.
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Chapter 6 - Symbiosis
Mutualism A form of symbiosis in which two organisms of different species both benefit from the interactions between them.
Related Glossary Terms Symbiosis
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Chapter 6 - Symbiosis
Parasites Organisms that engage in parasitism with another animal. Parasites usually live on or in another animal and live off of the body fluids of that animal.
Related Glossary Terms Parasitism
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Chapter 6 - Parasitism
Parasitism A symbiotic relationship in which one organism survives by living off of the resources of another organism, while the second organism is negatively affected by the interactions with this first organism, which is called a parasite.
Related Glossary Terms Parasites, Symbiosis
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Chapter 6 - Symbiosis
Predator Another name for a carnivore. The term predator is usually used when describing the relationship with a carnivore and the animals it eats, called prey.
Related Glossary Terms Carnivore, Prey
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Chapter 4 - Carnivore 1
Prey An animal that is eaten by a carnivore.
Related Glossary Terms Predator
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Chapter 4 - Carnivore 1
Symbiosis An interaction between two organisms of different species other than predator-prey relationships.
Related Glossary Terms Camouflage, Commensalism, Mutualism, Parasitism
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Chapter 6 - Symbiosis