Lesson 6.2: Communities & Symbiosis

*Refer to Chapter 16 in your Textbook

Learning Goals: 1. I can describe interactions that occur in a

community.2. I can differentiate between the types of

symbiosis.

Interactions within a Community: Predation: occurs when one organism hunts (predator)

another organism (prey) to consumeExample: A leopard seal (predator) hunts and eats an

emperor penguin (prey) in Antarctica.

Interactions within a Community: Competition: fighting over a resource such as food,

shelter, or a mate; can occur 2 ways: 1. Intraspecific: between the same species

Ex. Hermit crabs compete for the biggest shell 2. Interspecific: between different species

Ex. Sponges & coral compete for plankton

Interactions within a Community: Keystone Species: a species that has vital importance

to its community; without the keystone species, the community would be drastically different Ex. Sea Otter – is a keystone species in a kelp forest. Sea otters

feed on sea urchins, which feed on kelp. Without the sea otter, the sea urchins would over populate. If there are too many sea urchins, there would eventually be no more kelp forest!

Interactions within a Community: Symbiosis: “living together” occurs when 2 different

species have a close relationship within a community. 3 types:

1. Mutualism2. Commensalism3. Parasitism

Types of Symbiosis: Mutualism: occurs when both species in the

relationship benefit in some way Ex. Clownfish & sea anemone – fish gets a free home & also

lures food in for the anemone to eat

Types of Symbiosis: Commensalism: occurs when 1 organism in the

relationship benefits without affecting the other oneEx. The remora fish attaches himself to a shark to gain a

free ride & protection from predators.

Types of Symbiosis: Parasitism: occurs when 1 organism in the relationship

benefits while harming the other one Ex. A tapeworm lives inside a polar bears gut and feeds off

his internal organs.