3) Omnivores – eat both plants and animals Examples: grasshopper mouse, humans Scavengers are omnivores that eat dead plants and animals. Examples: turkey vulture
3. Decomposers – organisms that get energy by breaking down dead organisms Examples: bacteria and fungi Remove stored energy from dead organisms They produce simple materials such as water and carbon dioxide which can be used by other living things Decomposers are important because they are nature’s recyclers!
A food chain is a diagram that shows how energy in food flows from one organism to another
A food web is a diagram that shows the feeding relationships between organisms in an ecosystem
An arrow goes from one animal to the next, showing where energy is going. The arrows point toward who is receiving the energy, or who is doing the eating. Example above: Energy is moving from the grass, to the mouse, to the owl. Or the grass is eaten by the mouse, and the mouse is eaten by the owl.
An Energy Pyramid is a triangular diagram that shows an ecosystem’s loss of energy, which results as energy passes through the ecosystem’s food chain. An energy pyramid has a large base and a small top Less energy is available at higher levels because only energy stored in the tissues of an organism can be transferred to the next level.
One species can be very important to the flow of energy in an environment Example is Gray Wolves Wolves are at the “top of the food chain” which means they are consumers that control a lot of other populations because they prey on large animals When the gray wolf population declined, other species, such as elk, were no longer controlled This led to overgrazing This led to lack of food for the elk and all other species dependent on the grass for food. Soon almost all of the populations in the area were affected by the loss of the gray wolves In 1995 Gray Wolves were reintroduced in an attempt to restore the natural energy flow, bringing populations back into balance.
Balance in Ecosystems As the wolf population returns, they will reduce the number of elk, which will allow more plants to grow, so the numbers in populations of animals that eat the plants will increase.
Most living things produce more offspring than will survive. Example: Frogs lay hundreds of eggs. Why don’t ponds and such become overrun with frogs? An organism, such as the frog, will interact with abiotic and biotic factors that can control population size.
1. Limiting Factors Populations cannot grow without stopping because the environment contains a limited about of food, water, living space, and other resources Limiting factors – resource that is so scarce that it limits population size
2. Carrying Capacity Carrying capacity – the largest population that an environment can support If a population becomes larger than its carrying capacity, limiting factors cause individuals to leave or die
Four Main Ways that Species and Individuals affect each other are:
1. Competition – when two or more individuals or populations try to use the same resource such as food, water, shelter, space or sunlight. Occurs between individuals within a population Example: elks competing for food in the winter Also happens between populations Example: different types of trees competing for sunlight
2. Predators and Prey The organism that is eaten is the prey The organisms that eats the prey is called the predator Example: When a bird eats a worm, the bird is the predator and the worm is the prey
Predator Adaptations – any characteristic that makes a predator better at catching prey
Prey Adaptations – any characteristic that keeps prey from being eaten
Defensive Chemicals: skunk or beetle smells, the acid of bees, ants, wasps, and deadly toxins on the skin of some animals like a poison arrow frog
Warning coloration – A physical advertisement that predators should look for another meal; predators will avoid any animal that has the colors and patterns they associate with pain, illness, or unpleasant experiences. The most common warning colors are bright shades of red, yellow, orange, black, and white Yellow Jacket Locust Borer (beetle)
3. Symbiosis – a close, long-term association between two or more species Individuals in a symbiotic relationship can benefit from, be unaffected by, or be harmed by the relationship
Mutualism – symbiotic relationship in which both organisms benefit Example: Bacteria living in your intestines Clown Fish and Sea Anemone
Commensalism – A symbiotic relationship in which one organism benefits and the other is unaffected Example: sharks and remoras
Parasitism – A symbiotic association in which one organism benefits while the other is harmed The organism that benefits is the parasite The organism that is harmed is the host The parasite gets nourishment while the host is weakened Sometimes a host dies Example: Mosquito and human
4. Coevolution – When a long-term change takes place in two species because of their close interactions with one another Example: the ant and the acacia tree Takes place between any organisms that live close together, but changes happen over a very long period of time
Coevolution and Flowers A pollinator is an organism that carries pollen from one flower to another Flowers have changed over millions of years to attract pollinators Because flowers and their pollinators have interacted so closely over millions of years, there are many examples of coevolution between them.