Symbiosis

Symbiosis

The intimate relationship between members of two different species that have co-evolved with each other

What are the two types of symbiosis?

Mutualism and parasitism

A parasite

This organism lives on another organism (the host) from which it obtains resources from

How does parasitism benefit the parasite and harm the host?

The parasite gains energy and nutrients from the host, whereas the host looses resources

Why do parasites need a host?

They have a limited metabolism

Transmission

This is when a parasite is passed to a new host

What three ways can parasites be transmitted by?

• Direct contact

• Released of resistant stages

• Vectors

Direct contact

When a parasite is passed from person to person or animal to animal

Release of resistant stages

Some parasites use resistant larvae and pupae, which can survive adverse environmental conditions until a new host comes into contact with them

Vectors

Some parasites use another species to transfer themselves from one host to another

Example: vectors

Malaria - female mosquitoes transmit the plasmodium parasite between humans through biting their blood to produce eggs

Secondary hosts

Some parasitic life cycles involve secondary hosts to allow them to complete their life cycle

Example: secondary hosts

Tapeworms - these lack their own digestive systems and so they live in the intestines of some animals, which is fine because the host has already digested the food

What is the most effective type of parasitic relationship?

One where the parasite does not kill the host (or at least not until completion of the parasitic life cycle is ensured)

Mutualism

This is when both of the mutualistic partner species benefit in an interdependent relationship

Example: mutualism

Cleaner fish feed off of the dead skin and parasites of larger fish such as sharks, providing the cleaner fish with food and protection and keeping the larger fish clean and less prone to infections