Symbiosis: Types of Relationships

I can describe the different ways organisms interact

with each other.

What is symbiosis?

Symbiosis is a situation where two types of organisms live closely together.

If the two organisms are separated, one (or BOTH) of them will die! (either immediately, or the population will over time)

Why live together?

There is always competition within an ecosystem for food, space and resources.

In order to survive, each organism occupies a NICHE, or specific role.

Organisms can avoid spending energy on competition by forming a relationship with another organism – they can share the same space and food supply.

Predator/Prey Relationship

Predator:

Prey:

Hunts or kills other organisms for food.

Animals that are food for other organisms.

Top Predator: Are not prey for any other organisms.

Predator/Prey Relationship

Predation is a strong, selective pressure that drives prey organisms to find ways to avoid being

eaten. Prey organisms that are difficult to find, catch or consume are the ones that will survive

and reproduce. The result is that over time, prey organisms have developed a stunning array of

strategies to avoid being eaten – ADAPTATIONS.

Examples of Predator/Prey

Lemming populations go through cycles of growth

and decline. When they are large, they eat all the moss and the population starves. This affects the snowy owls – they will only reproduce if

the lemming populations are large enough for the owls to feed themselves

and their chicks.

Snowy Owls and Lemmings

Examples of Predator/Prey

In Michigan, all the top predators, such as the grey wolf, cougar, and

American black bear, have dwindling populations. Without these

predators, the white tailed deer population has grown so large that there is not enough food for all the

deer. The growing human population has also decreased the amount of natural habitat for the deer. The

Michigan state government allows human hunting of deer to help limit

the population size and prevent death by starvation.

Top Predators and White Tailed Deer

Mutualistic Relationship

Mutualism is where both organisms BENEFIT from the relationship.

Example of Mutualism

A type of bird, called oxpeckers (or tick birds), rides upon the

back of African rhinos. The oxpeckers protect the rhinos from parasites by eating ticks off the rhinos. The rhinos give

the birds a place to live and something to eat.

Oxpeckers and African Rhinos

Example of Mutualism

Another example involves the acacia plant and african ants.

The ants act as a defense mechanism, protecting the plant

from other insects or animals. The plant in return provides the ants with precious nutrients that

have no other purpose other than to help the ants.

Acacia Plant and African Ants

What is Commensalism?

Commensalism is a relationship between two organisms where one benefits and the other is unaffected.

Example of Commensalism

Barnacles are sedentary creatures, so adults

attach themselves to whales, who transport them to areas where food is available. The

barnacles do not affect the whales in any way.

Barnacles and Whales

Example of Commensalism

Orchids are plants with beautiful flowers that are

found in the rainforest. They have adapted to grow on top

of other trees and larger plants in order to get more

light to perform photosynthesis. They do not harm or affect the trees they grow on – they do not take

the tree’s nutrients.

Orchids and Trees

What is Parasitism?

Parasitism is a relationship where one organism is benefited, and the other is harmed in some way.

Example of Parasitism

Lice live exclusively on the scalps of humans, and they

feed off human blood. In return, they cause a rash and irritation to the human host.

Lice and Humans

Example of Parasitism

Caterpillar wasps lay their eggs inside or on a caterpillar.

When the eggs hatch, they feed on the caterpillar,

causing it to die.

Some plants actually release secretions that attract caterpillar wasps when

caterpillars start eating their leaves.

Caterpillar Wasps and Caterpillars

Which type of symbiosis is being shown?

The human intestine contains many different kinds of bacteria. The bacteria break down and process food and help fight disease, in turn they get a place to

live without any predators or competition from other bacteria for food.

The Great Burdock is a plant that produces seeds in a hooked casing. This casing allows the seed to hook onto the fur of animals passing by without

hurting them, and the animals spread the seed to new locations.

Which type of symbiosis is being shown?

Your Task:

BACKGROUND: Relationships aren’t always love-love in biology, nor are they always love-hate. Relationships among organisms can take on many different meanings. Coevolution is the result of an association between two species in which they evolve together and develop such a close relationship that one needs the other for survival. If both organisms benefit from the relationship, it’s called mutualism. If one benefits, and the other gets nothing, it is called commensalism. However, if one organism benefits while the other is harmed then the relationship is considered parasitism.

WHAT TO DO: Create a classified advertisement/want ad for a job opening in which an organism in a symbiotic relationship is looking for the other organism. The ad should be based on mutualism, parasitism, or commensalism. The ad should be from the point of view of the organism that benefits from the relationship (for example, if the relationship is an example or parasitism, the organism getting harmed wouldn’t be seeking out the organism that would harm it). The ad can be down as a PowerPoint presentation, brochure, newspaper ad, magazine ad, poster, prezi presentation, glogster, etc.