Community Interactions

Community: Many different species interacting in the same environment. Three types of interactions: – Competition – Predation – Symbiosis

Competition Defined: competing for resources – water, nutrients, light, food – occurs due to a limited number of resources Intraspecific competition: When organisms of the same species compete for resources. Interspecific competition: When organisms of differing species compete for resources. Competitive exclusion principle: no two species can occupy the same niche in the same habitat at the same time

Predation Defined: when an organism captures and feeds on another organism. Predator- hunter Prey- hunted

Symbiosis Defined: any relationship where two species live closely together. Three types – Mutualism – Commensalism – Parasitism

Mutualism Defined: both species benefit from a relationship. Ex: Lichens (fungus and Algae) Ex: Clown fish and anemones Ex: Cleaner birds and crocodiles Fungus obtains nutrients from the algae Algae lives amongst the fungal cells Fish receives protection and a home Anemone feeds on undigested food from the fish Bird receives food Crocodile has parasites removed

Commensalism Defined: One member of a symbiotic relationship benefits and the other is neither helped nor harmed Ex: Cattle and Birds – Birds eat insects stirred up by the cattle Ex: Barnacles and whales – Barnacles grow on whale

Parasitism Defined: One creature benefits and one creature is harmed Endoparasitism: A parasite that inhabits the inside an organism. – Ex: Tapeworm feeds within a human’s intestines absorbing his/her nutrients Ectoparasitism: A parasite that inhabits the outside of an organism. – Ex: A leech feeds on the blood of an organism from a host’s skin.

Review 1)What is a community? 2)Name the 3 types if community interactions. 3)When do organisms usually compete? 4)How do predators and prey interact? 5)Name the 3 types of symbiosis. 6)How is predation and parasitism differ? 7)How does mutualism, commensalism, and parasitism differ?