ECOLOGY & FOODWEBS

UNIT 2: S7L4 Students will examine the dependence of organisms on one another and their environments. A. Demonstrate in a food web that matter is transferred from one organism to another and can recycle between organisms and their environments. B. Explain in a food web that sunlight is the source of energy and that this energy moves from organism to organism. C. Recognize that changes in environmental conditions can affect the survival of both individuals and entire species. D. Categorize relationships between organisms that are competitive or mutually beneficial.

EQ’s to be answered in this unit: How is life like a web? Why is it necessary for everything in an ecosystem to work together? How do YOU fit into the larger world? How does a change in temperature and/or precipitation affect the living things in the environment? Why can’t there be a lone survivor? What effect does the environment have on organisms? How does the environment affect us?

Habitats An environment that provides the things that an organism needs to live, grow, and reproduce. Organism A single living thing (plant, animal, fungus, protist, bacteria) Needs food, water, & shelter

Organisms Interact With Both: Biotic Factors Any plant or animal; living things Abiotic Factors Objects that do not have living characteristics; non- living things Example: water, sunlight, oxygen, temperature, soil

Population vs. Community Species A group of organisms that are physically similar and can mate with each other Example: bear Population All members of one species in a particular area Example: a group of deer in a forest Community All different populations that live together in an area and are close enough to interact with each other Example: birds, bears, snakes, all living in the forest

ECOSYSTEM LEVELS of ORGANIZATION: Species: Prairie Dog The community of organisms that live in a particular area, along with their nonliving surroundings, make up an ecosystem. Example: Prairie, mountain streams, deep oceans, and forests LEVELS of ORGANIZATION: Species: Prairie Dog Population: Prairie Dog Town Community: All the living things that interact on the prairie (grass, prairie dogs, skunks) Ecosystem: All the living & nonliving things that interact on a prairie (grass, owls, prairie dogs, snakes, sun, water, soil)

Where Does Energy Comes From? SUN Provides energy for life on Earth

2 Ways To Obtain Energy Producers Consumers Organism that can make its own food using the Sun Example: Plants Consumers Organism that gets energy by feeding on other organisms Example: Animals

How Do They Get Energy? Here is how energy passes from one organism to another. PRODUCERS will ALWAYS be first. Producers make their own food. CONSUMERS will be next: herbivore An organism that eats only plants (ex: rabbit, deer) carnivore An organism that eats other animals (ex: hawk, wolf) omnivore An organism that eats both plants and animals (ex: bear, human)

How Do They Get Energy? Here is how energy passes from one organism to another. scavenger A carnivore that feeds on the bodies of dead organisms (ex: vultures) decomposer An organism that breaks down chemicals from wastes and dead organisms, and returns important materials to the soil and water. (ex. fungi & bacteria)

Interactions of Living Things There are three major types of interactions among organisms: Predation An interaction in which one organism kills another for food Competition The struggle between organisms to survive as they attempt to use the same limited resources Symbiosis A close relationship between two species that benefits at least one of the species

Interactions of Living Things An interaction in which one organism kills another for food is called predation. A tiger shark lurks below the surface of the clear blue water, looking for shadows of albatross chicks floating above. The shark spots a chick and silently swims closer. Suddenly, the shark bursts through the water and seizes the albatross with one snap of its powerful jaw. This interaction between two organisms has an unfortunate ending for the albatross. predator The organism that does the killing prey The organism that is killed

Interactions of Living Things The struggle between organisms to survive as they attempt to use the same limited resources is called competition. In any ecosystem, there is a limited amount of food, water, and shelter. Organisms that survive have adaptations that enable them to reduce competition. Adaptations are behaviors or physical characteristics that allow organisms to be successful in their environment.

NICHE-Organism Survival A Niche is the role of an organism in its habitat, or how it makes its living. Consists of a variety of adaptations that are suited to the organisms specific living conditions. How does it find food and shelter? How does it avoid danger? How does it care for its young? Does it have predators? Can it cooperate with other animals? Can it find prey (food)?

Interactions of Living Things A close relationship between two species that benefits at least one of the species is called symbiosis. There are three types of symbiotic relationships: Mutualism: A relationship in which BOTH species benefit. Commensalism: A relationship in which ONE species benefits and the other species is neither helped nor harmed. Parasitism: A relationship in which one organism lives ON or IN another organism and HARMING it.

Interactions of Living Things A close relationship between two species that benefits at least one of the species is called symbiosis. Mutualism: A relationship in which BOTH species benefit. Example: + birds that ride on a rhino’s back they eat bugs & ticks on the rhino’s back they get food and the rhino gets clean

Interactions of Living Things A close relationship between two species that benefits at least one of the species is called symbiosis. Commensalism: A relationship in which ONE species benefits and the other species is neither helped nor harmed. Example: + birds that build nests in tress the bird now has shelter but the tree is not helped or harmed by this interaction.

Interactions of Living Things A close relationship between two species that benefits at least one of the species is called symbiosis. Parasitism: A relationship in which one organism lives ON or IN another organism and HARMING it. A parasite is the organism that lives on or in another organism and is benefitting. A host is the organism that the parasite is living on or in. Example: a tick living on a dog

Mutualism – Bees & Flowers Parasitism – Ticks Mutualism – Bees & Flowers Commensalism – Fish & anemones

ENERGY FLOW Energy is transferred from one organism to another. The movement of energy through an ecosystem can be shown in diagrams. Two diagrams of energy transfers Food Chain/Food Web Energy Pyramid

Tree  Carpenter Ant  Woodpecker Food Chains A food chain is a series of events in which one organism eats another and obtains energy. The first organism in a food chain is ALWAYS a producer! The second organism feeds on the producer and is called a first-level consumer. Next, a second-level consumer eats the first-level consumer. Finally, a third-level consumer may eat a second-level consumer. TREE (a PRODUCER is eaten by a) CARPENTER ANT (a FIRST-LEVEL CONSUMER which is eaten by) a WOODPECKER (a SECOND-LEVEL CONSUMER) Tree  Carpenter Ant  Woodpecker

EXAMPLE GRASS RABBIT WOLF Producer Herbivore Carnivore

Food Webs A food chain shows only ONE possible path along which energy can move through an ecosystem. A food web consists of many overlapping food chains in an ecosystem. The arrows show the direction the energy is traveling.

ENERGY PYRAMID When an organism eats, it obtains energy. The organism uses some of this energy to move, grow, reproduce, and carry out other life activities. Only some of the energy obtained is available to the next organism in the food web. An energy pyramid is a diagram that shows the amount of energy that moves from one feeding level to another in a food web.

ENERGY PYRAMID: Carnivores Least Energy Third-level Consumers Carnivores Second-level Consumers Herbivores First-level Consumers Producers Most Energy

ENERGY PYRAMID Only about 10% of the energy at one level of a food web is transferred to the next higher level The other 90% is used for the organism’s life processes Since 90% of the energy is lost at each step, there is not enough energy to support many feeding levels in an ecosystem. This is why there are few organisms at the highest level in a food web.

Limiting Factors A limiting factor is an environmental factor that causes a population to decrease. Limiting factors include: Food & Water: If it runs out… populations will get smaller. Space: Plants need room to grow or… populations will get smaller. Weather: temperature & rainfall can kill off populations or make them breed more. Hurricanes & floods can wash away nests…populations will get smaller.

Means of Dispersal The movement of organisms from one place to another is called dispersal. Dispersal can be caused by: Wind & Water: Wind can disperse seeds, spores of fungi, tiny spiders, and other small, light organisms. Water transports objects that float such as coconuts and leaves which could be harboring small animals. Other Living Things: A bird may eat berries and deposit seeds as wastes. Animals may carry sticky plant burs. Humans can also disperse organisms.

Limits to Dispersal Three factors that limit dispersal of a species: Physical barriers – water, mountains, and deserts are hard to cross and can limit movement. Competition – Find a unique niche or compete for resources. Climate – the typical weather pattern in an area. Organisms stick to the area they are adapted to.

Let’s see if you can answer the EQ’s: How is life like a web? Why is it necessary for everything in an ecosystem to work together? How do YOU fit into the larger world? How does a change in temperature and/or precipitation affect the living things in the environment? Why can’t there be a lone survivor? What effect does the environment have on organisms? How does the environment affect us?