Ecological interactions describe the relationships between organisms living in the same environment. The major interactions covered here are Commensalism, Mutualism, Parasitism, Neutralism, Competition, and Predation.
Commensalism is a type of symbiotic relationship in which one organism benefits while the other organism is neither helped nor harmed.The benefiting organism may receive:
The host species remains unaffected.
One organism uses another solely for transportation.
One organism uses another organism as a permanent shelter or housing site.
One organism benefits from the waste products, dead remains, or habitat created by another organism.
Microorganisms colonize the body or surface of a host and obtain nutrients without causing disease or infection.
Remoras attach to sharks using a specialized sucker.Benefits to Remora:
Effect on Shark:
Grazing animals stir insects from grass.Benefits to Egret:
Effect on Grazing Mammal:
Barnacles attach to whale skin.Benefits to Barnacles:
Effect on Whale:
Orchids grow on tree branches.Benefits to Orchid:
Effect on Tree:
Hermit crabs occupy discarded shells of dead gastropods.Benefits to Hermit Crab:
Effect on Original Shell Owner:
Clownfish live among stinging tentacles.Benefits to Clownfish:
Effect on Anemone:
Birds construct nests on tree branches.Benefits to Birds:
Effect on Tree:
Bacteria live on human skin.Benefits to Bacteria:
Effect on Humans:
Mutualism is a biological interaction in which both organisms benefit.The relationship enhances:
Neither organism is harmed.
Both species are completely dependent on each other for survival.If the relationship ends, one or both organisms may die.
Both species benefit, but each can survive independently.
Benefits to Bees:
Benefits to Plants:
Benefits to Clownfish:
Benefits to Anemones:
Benefits to Ants:
Benefits to Trees:
Benefits to Plants:
Benefits to Fungi:
Partnership between:
Benefits to Fungus:
Benefits to Algae/Cyanobacteria:
Benefits to Plants:
Benefits to Bacteria:
Parasitism is a biological relationship where a parasite benefits while the host is harmed.The parasite feeds on, lives in, or utilizes the host.
Live on the outer surface of the host.
Ticks and Fleas
Leeches
Lice
Live inside the host body.
Tapeworms
Plasmodium (Malaria Parasite)
Hookworms
Obtain nutrients from host plants.
Mistletoe
Dodder
One species manipulates another species into raising its offspring or performing work.
Cuckoos and Cowbirds
Parasitic Ant Species
A parasite itself becomes host to another parasite.
One organism permanently attaches to another and becomes dependent.
Male Anglerfish
Parasite eventually kills its host.
Neutralism is an interaction where two species coexist without affecting each other positively or negatively.Neither species:
True neutralism is considered extremely rare because ecosystems are highly interconnected.
Countries such as:
Avoided alignment with:
Competition is a rivalry among organisms, individuals, or groups seeking the same limited resource, goal, or opportunity.Competition promotes:
Companies sell similar products to the same customers.
Many firms sell identical products.
Market dominated by a few large firms.
Teams or individuals compete for championships.
Occurs within the same species.
Occurs between different species.
Multiple individuals compete for limited opportunities.
Employees compete for rewards.
Predation is an ecological interaction in which a predator hunts, kills, and consumes prey.It facilitates:
Animals kill and consume other animals.
Animals consume plant parts.
A specialized form of predation.
Occurs among insects and microorganisms.
Transfers energy through trophic levels:Plant → Herbivore → Carnivore.
| Interaction | Effect on Species 1 | Effect on Species 2 |
|---|---|---|
| Mutualism | Benefits | Benefits |
| Commensalism | Benefits | Unaffected |
| Parasitism | Benefits | Harmed |
| Neutralism | Unaffected | Unaffected |
| Competition | Negative impact due to resource rivalry | Negative impact due to resource rivalry |
| Predation | Benefits (Predator) | Harmed/Killed (Prey) |
| Relationship | Effect on Species 1 | Effect on Species 2 | Definition | Examples |
|---|---|---|---|---|
| Mutualism (+/+) | Benefits | Benefits | Both organisms benefit from the interaction. | Bees–Flowering Plants, Clownfish–Sea Anemones, Acacia Ants–Acacia Trees, Mycorrhizal Fungi–Plant Roots, Lichens (Fungus + Algae), Rhizobium–Legumes |
| Commensalism (+/0) | Benefits | Unaffected | One organism benefits while the other is neither helped nor harmed. | Remora–Shark, Cattle Egret–Grazing Mammals, Barnacle–Whale, Orchid–Tree, Hermit Crab–Discarded Snail Shell, Birds–Trees, Skin Bacteria–Humans |
| Parasitism (+/-) | Benefits (Parasite) | Harmed (Host) | Parasite obtains food, shelter, or resources at the expense of the host. | Tick–Dog, Flea–Cat, Louse–Human, Tapeworm–Human, Plasmodium–Human, Hookworm–Mammals, Mistletoe–Tree, Dodder–Host Plant |
| Predation (+/-) | Benefits (Predator) | Harmed/Killed (Prey) | Predator hunts, kills, and consumes prey. | Lion–Zebra, Wolf–Moose, Owl–Mouse, Shark–Seal, Ladybug–Aphid, Venus Flytrap–Fly |
| Herbivory (+/-) | Benefits (Herbivore) | Harmed (Plant) | Animal feeds on plant tissues. | Deer–Grass, Elephant–Tree Leaves, Seed-Eating Birds–Seeds |
| Competition (-/-) | Harmed | Harmed | Both organisms compete for limited resources. | Lion–Hyena, Two Male Deer Competing for Mates, Plants Competing for Sunlight |
| Neutralism (0/0) | Unaffected | Unaffected | Two species coexist without significant effect on each other. | Cactus–Tarantula, Rainbow Trout–Dandelion, Deer–Woodpecker |
| Parasitoidism (+/-, Host Dies) | Benefits (Parasitoid) | Eventually Killed | Parasite-like interaction where host is ultimately killed. | Parasitoid Wasp–Caterpillar |
| Phoresy (Commensalism) | Benefits | Unaffected | One organism uses another for transport. | Remora–Shark, Barnacle–Whale |
| Inquilinism (Commensalism) | Benefits | Unaffected | One organism uses another as shelter. | Orchid–Tree, Birds Nesting in Trees |
| Metabiosis (Commensalism) | Benefits | Unaffected/Dead Organism | One organism uses remains or structures created by another. | Hermit Crab–Empty Snail Shell |
| Microbial Commensalism (+/0) | Benefits | Unaffected | Microbes obtain nutrients without harming host. | Skin Bacteria–Humans |
| Brood/Social Parasitism (+/-) | Benefits (Parasite) | Harmed | One species forces another to raise its offspring or perform work. | Cuckoo–Host Bird, Cowbird–Host Bird, Parasitic Ant–Host Ant Colony |
| Hyperparasitism | Benefits (Secondary Parasite) | Harmed (Primary Parasite) | A parasite parasitizes another parasite. | Protozoan → Flea → Dog |
| Sexual Parasitism | Benefits (Male) | Supports Male | One organism permanently attaches and depends on another. | Male Anglerfish–Female Anglerfish |