ORGANISMS CAN INTERACT IN DIFFERENT

WAYS• ORGANISMS INTERACT IN

DIFFERENT WAYS• SURVIVAL OF ONE SPECIES MIGHT

DEPEND ON ANOTHER SPECIES– SYMBIOSIS = relationship between

individuals of 2 different species who live together in a close relationship (word means “living together”)

• INTERACTIONS IN AN ECOSYTEM ARE COMPLEX

Organisms Interact in Different Ways

• PREDATOR/PREY: predator is an animal that eats another; prey is an animal eaten by a predator; in a food chain, an animal may be both(a small bird feeds on grasshopper, then is eaten by a falcon).

• The sick & elderly usually are the members of a population that are eaten; prey may affect the location of predators (birds will go where the insects are).

• COMPETITION: struggle between individuals or different populations for a limited resource.

• Competition may occur within same species (plants compete for light & nutrients) or different species (strangler fig vines compete with trees for water light & nutrients, eventually killing it).

Organism Interactions Con’t.• COMPETITION CON’T.: occurs between & within

species (vultures & hyenas compete for remains of dead animals- wolves compete with each other over territory); within species competition often occurs during mating season. Many populations can coexist in a habitat without competition also (maple, beech, & birch trees side by side).

• COOPERATION: an interaction in which organisms work in a way that benefits them all. (some predators hunt in packs- killer whales, lions, wolves, etc.)

• Ants, bees, & termites are social insects; members of a colony belong to different groups called castes & have different responsibilities (gather food, defend colony)

• Apes & monkeys live in family groups, & members cooperate to take care of the young.

Organisms Interacting

Survival of 1 Species may Depend on Another

• Symbiotic Relationships: both species benefits, 1 benefits & other isn’t affected, & 1 benefits while other is harmed.

• MUTUALISM= interaction between 2 species that benefits both. (bee gets nectar from flower, & flower gets pollinated).– Many plants rely on mutualism to reproduce (insects &

birds get nectar & in turn pollinate, or animals eat fruit & disperse seeds).

– Mutualism might be necessary for survival of organism (termites live off of wood because have one-celled protozoa making homes in their gut and they digest the wood into usable nutrients).

Species Survival con’t.• COMMENSALISM: relationship between 2 species

where 1 benefits & other is unaffected. Orchids & mosses grow on trees to get light & nutrients that run down along tree, tree remains unaffected.

• Commensal relationships common in ocean ecosystems (remoras stick to sharks to eat scraps leftover; fish swimming among jellyfish tentacles for safety).

• PARASITISM: one species benefits while other is harmed. Parasites (ticks, lice, mites) feed off & weaken their hosts. Tapeworms & ringworms are internal parasites living inside of host.– Nest or Brood Parasitism= female cowbird lays eggs

in a warbler’s nest, often pushing out warbler eggs.

Species Survival Relationships

Complex Interactions in Ecosystem