Symbiotic Relationships Objectives of the Symbiotic Relationships Lesson

Symbiotic Relationships

Objectives of the Symbiotic Relationships Lesson § Students will investigate how organisms or populations interact with one another through symbiotic relationships and how some species have become so adapted to each other that neither could survive without the other. (Ohio Academic Standards LS 7. 1) § Students will be able to define and identify the following relationships: § Parasitism § Mutualistism § Commensalism § Neutralism § Competition

Symbiotic Relationships § Definition: A relationship between two kinds of organisms that lasts over a period of time is called symbiosis. § The word symbiosis can be broken down into two parts to determine its meaning. § sym means together (like in the words sympathy and symphony) § bio mean life (like in the words biology and biome)

Parasitism

Parasitism § Parasitism is the situation where one organism benefits while the other is harmed. § A + / - relationship. § Think of a friendship where you might feel Parasitic Isopod on fish used by your friend.

Tapeworms § The definitive host of the cucumber tapeworm is a dog or a cat (occasionally a human). Fleas and lice are the intermediate host. the dog or cat becomes contaminated when the eggs are passed in the feces, and the flea or louse ingests the eggs. The dog or cat (or human) is infected when they ingest a flea or louse. Hence the importance of controlling fleas on your pet!

Bedbugs § Bedbugs are small, nocturnal parasites that come out of hiding at night to feed on unsuspecting humans. They feed exclusively on blood! Their bites often result in an allergic reaction.

Acacia plant with ant galls Ants lay eggs on acacia tree Acacia covers the infected area with brown flesh (gall) Parasitism: one benefits, one is harmed

Taenia worm in human eye Worm infects human blood stream Human may go blind Parasitism: one benefits, one is harmed

Commensalism

Commensalism is where one species benefits while the second species remains unaffected. A + / 0 relationship Think of a friendship where one of the friends benefits while the other doesn’t change. Barnacles adhering to the skin of a whale

Cattle with cattle egrets Cattle stir up insects as they eat grass Egrets hang around and eat insects Commensalism: one benefits, one is unaffected

Mutualism

Mutualism § Mutualism is where both organisms benefit from the relationship. § A + / + relationship. § Think of a normal friendship where both friends gain The clownfish and sea anemone are an example of mutualism. Although these anemones stun and devour something from the other species of fish, clownfish are not harmed. friendship. Clownfishes were thought to be commensal on the giant sea anemones, but there now is evidence that the aggressively territorial clownfishes chase away butterfly fishes, who eat anemone tentacles.

Mutualism § Both organisms benefit from the relationship Otters and Kelp The otters help the kelp by eating the sea urchins which endanger it. The kelp provides and anchor for the otters while they sleep.

Moray Eel with Cleaner Fish Moray Eel gets a clean mouth Cleaner Fish gets a meal Mutualism: both benefit

Antelope with Oxbird Antelope gets rid of parasites Oxbird gets a meal Mutualism: both benefit

Predation

What type of relationship is this? Can you guess? The picture shows a shark going after the small fishes to eat them. The small fishes are helpless! In this type of relationship, the shark is the predator, much bigger and powerful, while the small fishes are the prey. They are directly attacked by the predator. This relationship is called predation. Do you know of other examples of this type of relationships?

Neutralism

§ Neutralism is the situation where both species remain unaffected. § A 0 / 0 relationship. § Think of someone you sit beside but never show any emotional either positive or negative.

Neutralism the most common type of interspecific interaction. Neither population affects the other. Any interactions that do occur are indirect or incidental. Example: the tarantulas living in a desert and the cacti living in a desert

Competition

§ Competition is where neither species benefits. § A - / - relationship. § Think of someone whom you are constantly at battle with.

COMPETITION: Scramble (Indirect) vs. Contest (Direct) Scramble: mutual use of limited resource § -Most plant competition is of this form Contest: interact directly (direct aggression or display)

Competition can be defined as an interaction between organisms or species, in which the fitness of one is lowered by the presence of another. Limited supply of at least one resource (such as food, water, and territory) used by both is required. Competition is one of many interacting biotic and abiotic factors that affect community structure

intraspecific competition - Competition among members of the same species interspecific competition between individuals of different species is known as

Amensalism

Amensalism between two species involves one impeding or restricting the success of the other while the other species has no effect on it. Do you know that there are organisms that may live together only for sometime because one species secrete a toxic or lethal substance that could kill the other species? Are you familiar with some of them? A certain species of Artemisia (damong maria) secrete a substance that can kill the grasses that may grow around them. This is an example of amensalism. It is a type of symbiosis. Usually this occurs when one organism exudes a chemical compound as part of its normal metabolism that is detrimental to another organism.

The bread mold Penicillium is a common example of this; penicillium secrete penicillin, a chemical that kills bacteria. A second example is the black walnut tree (Juglans nigra), which secrete juglone, a chemical that harms or kills some species of neighbouring plants, from its roots. This interaction may still increase the fitness of the nonharmed organism though, by removing competition and allowing it access to greater scarce resources. In this sense the impeding organism can be said to be negatively affected by the other's very existence, making it a +/- interaction. A third simple example is when sheep or cattle make trails in grass that they trample on, and without realizing, they are killing the grass.

Saprophytism

Since one of the characteristics of fungi is that they are unable to produce their own food by photosynthesis, due to the lack of choloroplasts, they obtain their food from other organisms. They also do not have mouths to take in food as animals do, therefore they absorb food through their plasma membranes and cell walls. One of the types of such heterotrophic food intake methods is saprophytism

Effects and examples § They break down wastes from dead organic matter and thereby enabling the constituent materials to be available for reuse by other organisms within the ecosystem. § dry rot, which occurs in wooden houses, and other wooden structures, causing the wood to deteriorate and the structure to fall apart

Cannibalism

Cannibalism Eating species of the same kind. Example: Human (Holocaust) Spider dog eating puppies

Cooperation

Cooperation § Helping same kind of organisms or organisms of different kind to get food. § Example: Ants in a colony § honeybee colony where the member carry out and follow specific task rigidly and work together for benefit of the group

For Practice A lichen is a combination of two organisms, an alga and a fungus. The fungus gets its food from the alga while the alga gets water from the fungus. This is an example of which relationship? a) Competition b) Mutualism c) Parasitism d) Commensalism

Let’s look at this again § If this were an example of competition, both of the organisms would be effected negatively. However, in this example neither organism is effected negatively. § Return to the question.

Good Job! § You’re right! This is an example of a mutualistic relationship. The alga gains water from the fungus and the fungus gains food from the alga. Both need each other to live and gain something from the other organism. § Go to the assignment

It’s interesting that you think this § In a parasitic relationship, one organism gains a positive while the other organism receives a negative. In this example, neither organism receives a negative. § Return to the question.

Can we talk about the example § In a commensalistic relationship, one organism gains something positive. The other organism remains unaffected by the relationship. In this example, both organisms are effected by the relationship. § Return to the question.

Terminology § Herbivory: an animal consuming plant material § 4 kinds of herbivores: § Grazers (aka folivores) consume leafy material § Browsers consume woody material and bark § Granivores consume seeds § Frugivores consume fruit