Biotic Relationships

There are three types of relationships between living organisms: predation, symbiosis, and competition.

1) Predation: occurs when an organism hunts and feeds on another organism. Example: snake and frog Prey: the organism that is eaten (frog) Predator: The organism that kills and eats (snake)

2) Symbiosis: Close interaction between two different species in which members of one species lives in, on, or near members of the other species These anglerfish can be over 1 meter in size! Bioluminescent bacteria live in the spine extending from the female fish’s head.

There are three types of symbiotic relationships: a) Mutualism: When both species benefit from the relationship. Example: bees and flowers  Bees feed on nectar and plants get pollinated.

Mutualism Another example: Goby fish and shrimp - The pistol shrimp builds a home for both the shrimp and the goby to live in. The goby fish has better eyesight than the shrimp and can watch for predators.

b) Commensalism: occurs when one species benefits from the relationship while the other species neither benefits nor is harmed Example: Bird building a nest in a tree. free transportation to food sources

c) Parasitism: One species lives on or in the other organism and feeds on it Example: Tapeworms attach to intestines and feed on partially digested food, depriving host of nutrients.

Parasitism Another example: When one of the mistletoe berries comes in contact with tree bark, it will send a thread like root into the bark. The mistletoe plant attaches itself to the tree. The mistletoe feeds off of the host plant’s food and water.

3) Competition: Interaction between two or more organisms competing for the same resource within a given habitat.

There are two types of competition: Intraspecific competition  competition within the same species. Example: Squirrels compete with each other for food and mates.

Intraspecific Competition Another example: Elephant seals compete with each other for mating dominance. They can weigh up to 8800 lbs!

b) Interspecific Competition competition with other species Example: oystercatcher birds will chase away gulls from their territory.

The role of an organism in an ecosystem is called its NICHE The role of an organism in an ecosystem is called its NICHE. For instance, the niche of a grey squirrel includes being prey to foxes, competing with chipmunks for nuts and seeds, being an omnivore, nesting in trees, and dispersing seeds.