Interactions in the Environment

In food relationships, nutrients (food) are transferred from one organism to another.

Nutritionally, Organisms are either: Autotrophs Can make their own food from inorganic compounds. Also called PRODUCERS. Example: Green Plants

Nutritionally, Organisms are either: Heterotrophs Cannot make their own food. Also called CONSUMERS. Must obtain their nutrients from the environment. They are classified according to the type of food they eat.

Heterotrophs Classification: Herbivores Carnivores Predators Scavengers Omnivores Detrivores

SYMBIOTIC RELATIONSHIPS SYMBIOSIS: Organisms of different species live together in close association. At least one member of the association benefits (gains) by the association. Mutualism, Commensalism Parasitism

MUTUALISM A relationship in which both organisms benefit. nitrogen-fixing bacteria A type of bacteria that lives in little knobs on the roots of peas and clover plants. These bacteria make important nitrogen compounds that are used by the plant and the plant supplies moisture and organic nutrients to the bacteria.

COMMENSALISM Two organisms of different species live in a relationship that is beneficial to one and the other is not affected. The remora (little fish) attaches itself to the shark’s body with little suction cups. The remora gets scraps of uneaten food from the shark, the shark is not harmed by the relationship.

PARASITISM One organism (the parasite) benefits and the other organism (the host) is harmed. Athlete’s foot fungus (parasite) feeds on the host organism (humans). The host is harmed by the relationship and the parasite benefits.

https://www.youtube.com/watch?v=qN2XMyxAs5o

COMPETITION Competition occurs when there is a struggle among organisms living in the same habitat (environment) for the same limited resources. Some of these resources are food, space, water, light, oxygen, and minerals. When two species compete intensely for the same resource, one species usually wins. Competition may result in the elimination of one species in the ecosystem. Competing species tend to reduce their use of common resources.

FOOD CHAINS Food passes through an ecosystem in a certain path known as Food Chain. Food chains involve the transfer of food materials from producer to primary consumer to secondary consumer to tertiary consumer. Each level on a food chain is a Tropic Level.

Tropic Levels Producer – green plants and other photosynthetic organisms. Producers change the energy of sunlight into the chemical energy of food. Primary Consumer – are always herbivores because they are the animals that eat green plants. Secondary Consumers – are animals that eat other animals (carnivores). These include predators and scavengers. Higher-Level Consumers – are organisms that eat secondary consumers. Decomposers – break down all organisms into chemical materials that are returned to the environment for use by other living organisms.

FOOD WEBS In a natural community, there are many interconnecting food chains. Most organisms eat more than one type of food. Most organisms are consumed (eaten) by more than one species of organism. The flow of energy and materials is much more complicated than a simple food chain.

SEASHORE FOOD WEB The interconnecting food chains of an ecosystem form a FOOD WEB.

PYRAMID OF ENERGY At each step on the food web, energy is transferred to the next higher level. Energy is “lost” at each food level, because much of the food energy taken in by a consumer is used in the process of metabolism. Less energy is available to the higher levels on the food chain.

PYRAMID OF ENERGY

PYRAMID OF BIOMASS The amount of organic matter in an ecosystem is its biomass. This pyramid shows that the total biomass an ecosystem can support decreases at each higher feeding level. This is because there is less energy available at each level. The greatest amount of biomass is found at the producer level, and degreases with each higher feeding level.