Symbiosis

Symbiosis

Middle School

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Learning Objectives

• Define symbiosis and its importance in various ecosystems.

• Describe the three main types of symbiosis: mutualism, commensalism, and parasitism.

• Distinguish between predation and competition as other key ecological relationships.

• Identify and classify real-world examples of interactions between different species.

Key Vocabulary

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Symbiosis

A close, long-term interaction between two different species, which can be beneficial, harmful, or neutral.

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Mutualism

A symbiotic relationship in which both of the organisms involved receive a benefit from the interaction.

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Commensalism

An interaction where one organism benefits, and the other is neither harmed nor helped in any way.

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Parasitism

A relationship where one organism, the parasite, lives on or inside a host, causing it harm.

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Predation

An interaction where a predator hunts and kills another organism, its prey, for its own food.

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Competition

A relationship where different organisms need the same limited resources, which negatively affects them all.

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What is Symbiosis?

• Symbiosis is a close, long-term interaction between two different species.

• Its name comes from the Greek 'sym' (together) and 'bio' (life).

• These relationships are fundamental to how ecosystems function around the world.

• Interactions use symbols: (+) for benefit, (-) for harm, and (0) for no effect.

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Multiple Choice

What is the primary definition of symbiosis?

• A relationship where two animals hunt together.

• A close, long-term interaction between two different species.

• Any interaction where one organism is harmed.

• A relationship that is only beneficial to both organisms.

The Three Types of Symbiosis

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Mutualism (+, +)

• ​This is a 'win-win' relationship where both organisms benefit from each other.

• ​​A bee gets nutritious nectar from a flower to use as food.

• ​The bee helps the flower reproduce by carrying pollen to other flowers.

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Commensalism (+, 0)

• ​One organism benefits from the relationship while the other is unaffected.

• ​​For example, barnacles attach themselves to a whale for a free ride.

• ​The whale is not harmed or helped in any way by them.

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Parasitism (+, -)

• ​This is a 'win-lose' relationship where one organism harms the other one.

• ​​The parasite benefits by living on or inside its host, harming it.

• ​A tick feeds on a deer’s blood, which may weaken the deer.

Multiple Choice

A barnacle attaches to a whale to travel to new locations, but the whale is not affected. What type of relationship is this?

• Mutualism

• Commensalism

• Parasitism

• Competition

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Predation and Competition

Predation (+, -)

• ​One animal, the predator, hunts and kills another animal, which is called its prey.

• ​​This interaction results in the immediate death of the prey, unlike in parasitism.

• ​A common example of predation is an owl hunting and eating a mouse.

Competition (-, -)

• ​This occurs when organisms need the same limited resources, like food, water, or mates.

• ​​It's a 'lose-lose' situation because both organisms are negatively affected by the interaction.

• ​For example, two male birds might compete with each other for the same female.

Multiple Choice

What is the main difference between predation and parasitism?

• Predation involves a predator killing its prey for food, while parasites typically live on or in a host without killing it.

• Predation benefits both organisms, while parasitism only benefits one.

• Predators are always larger than their prey, while parasites are always smaller.

• Predation only happens between animals, while parasitism can happen with plants.

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Common Misconceptions

Misconception	Correction
Symbiosis only means both organisms benefit.	Symbiosis is any close relationship: beneficial, neutral, or harmful to one partner.
Predation and parasitism are the same.	Predators kill their prey, while parasites benefit from keeping their host alive.
Competition is a type of symbiosis.	Symbiosis requires close living, while competition is a struggle for resources.

Multiple Choice

A golden jackal follows a tiger to feed on the remains of its kills. The tiger is unaffected. Which set of symbols best represents this relationship?

• (+, +)

• (+, 0)

• (+, -)

• (-, -)

Multiple Choice

Why is competition considered a lose-lose (-, -) relationship for the organisms involved?

• Because they both must expend energy or share a limited resource, reducing success for both.

• Because one organism always dies during the struggle.

• Because they are forced to live in close contact with each other.

• Because the resource they are fighting for is destroyed in the process.

Multiple Choice

A yucca moth pollinates a yucca flower, which is essential for the flower's reproduction. The moth also lays its eggs in the flower, and the larvae eat some of the developing seeds. How would you classify this complex relationship and why?

• Purely Parasitism, because the larvae harm the plant's seeds.

• Primarily Mutualism, because the plant's reproduction depends entirely on the moth, outweighing the seed loss.

• Commensalism, because the plant isn't significantly harmed by the seed loss.

• Competition, because the moth and the plant are fighting over the seeds.

Multiple Choice

Mistletoe is a plant that grows on a spruce tree. It takes water and nutrients from the tree, weakening it. If a severe drought strikes the forest, what is the most likely immediate outcome?

• The mistletoe will help the tree find more water.

• The already-weakened tree is more likely to die from the lack of water, which will also lead to the death of the mistletoe.

• The mistletoe will detach from the tree to find a healthier host.

• The tree will shed the mistletoe to conserve its own resources.

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Summary

• Symbiosis is any close, long-term relationship between two different species.

• Types of symbiosis include mutualism (+,+), commensalism (+,0), and parasitism (+,-).

• Predation (+,-) involves a predator hunting and killing its prey for food.

• Competition (-,-) occurs when organisms require the same limited resources.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

• 1

• 2

• 3

• 4