Glossary
10% Rule
The principle stating that only about 10% of the energy from one trophic level is transferred to the next, with the remaining 90% lost as heat.
Example:
If producers have 10,000 units of energy, the 10% rule means primary consumers will only receive about 1,000 units.
Commensalism
A symbiotic relationship where one species benefits, and the other is neither harmed nor helped.
Example:
Barnacles attaching to a whale's skin for transport and feeding opportunities, without affecting the whale, is commensalism.
Competition
An interaction between organisms or species that require the same limited resources, leading to a struggle for survival.
Example:
Two different species of birds vying for the same type of insect in a tree demonstrates competition for food resources.
Consumers (Heterotrophs)
Organisms that obtain energy by consuming other organisms, as they cannot produce their own food.
Example:
A bear eating berries and fish is a consumer, relying on other life forms for its energy.
Decomposers
Organisms, primarily bacteria and fungi, that break down dead organic matter and waste, returning nutrients to the ecosystem.
Example:
Mushrooms growing on a fallen log are decomposers, breaking down the wood and recycling its nutrients.
Detritivores
Organisms that feed on detritus, which includes dead organic matter and waste products.
Example:
A dung beetle rolling and consuming animal waste is a detritivore.
Food Chain
A simple, linear sequence showing how energy is transferred from one organism to another through feeding relationships.
Example:
Grass → Grasshopper → Frog → Snake → Hawk represents a basic food chain.
Food Web
A complex and interconnected network of feeding relationships within an ecosystem, showing multiple pathways of energy flow.
Example:
In a forest, a food web would illustrate how deer eat plants, wolves eat deer, and bears eat both plants and deer, showing multiple interconnections.
Keystone Species
A species that has a disproportionately large effect on its environment relative to its abundance, crucial for maintaining ecosystem structure.
Example:
Sea otters are a keystone species in kelp forests because they control sea urchin populations, preventing them from overgrazing kelp.
Mutualism
A symbiotic relationship where both interacting species benefit from the interaction.
Example:
Bees pollinating flowers is an example of mutualism, as bees get nectar and flowers are fertilized.
Parasitism
A symbiotic relationship where one organism (the parasite) benefits at the expense of the other (the host), which is harmed.
Example:
A tapeworm living in the intestines of a mammal, absorbing nutrients and causing harm, demonstrates parasitism.
Predator-Prey Relationships
An interaction where one organism (the predator) hunts and kills another organism (the prey) for food.
Example:
A lion chasing and catching a zebra illustrates a predator-prey relationship.
Primary Consumers (Herbivores)
Organisms that feed directly on producers, typically plants or algae.
Example:
A rabbit munching on a carrot is a primary consumer.
Producers (Autotrophs)
Organisms that produce their own food, typically using sunlight through photosynthesis, forming the base of most food chains.
Example:
Algae in a pond are producers, converting solar energy into chemical energy for other organisms.
Resource Partitioning
When different species use the same limited resources in different ways or at different times to avoid direct competition.
Example:
Several bird species feeding on insects from different parts of the same tree (e.g., canopy vs. trunk) is an example of resource partitioning.
Scavengers
Organisms that consume dead animals that they did not kill themselves.
Example:
A vulture feeding on a carcass is a scavenger.
Secondary Consumers (Carnivores)
Organisms that feed on primary consumers.
Example:
A snake eating a mouse is a secondary consumer.
Symbiotic Relationships
Close and long-term interactions between two different biological species.
Example:
The relationship between clownfish and sea anemones is a classic example of a symbiotic relationship.
Tertiary Consumers (Top Carnivores)
Organisms that feed on secondary consumers, often at the top of the food chain.
Example:
An eagle preying on a snake is a tertiary consumer.
Trophic Levels
Hierarchical levels in an ecosystem, representing the position an organism occupies in a food chain based on its primary source of energy.
Example:
In a forest, the deer are at a different trophic level than the wolves that hunt them.