Notes on Living Things and Their Environment

Ecosystem Unit Notes

1. Organism – any living thing (ex: 1 trout, 1 frog, 1 bear)

2. Population - group of organisms of same type of species that

live together in same area. (ex: trout in a stream; redwoods in

a forest; frogs in a pond)

3. Community - living part of any ecosystem - all the different

populations living together in an area. (ex: pond community:

has lily pads, frogs, fish, insects, cat tails, etc)

4. Ecosystems - all living and nonliving things in an area that

Interact with one another – the community and the environment.

(ex: forest, ocean, drop of water, solar system)

a. Ecosystems can be as tiny as drop pond water or a garden and as

large as ocean, forest, or planet – it’s size is defined by the person

studying it.

b. Ecosystems are not isolated; they overlap & affect one another. (ex: grizzly [forest] eats salmon

[stream]; owl [mountains] eats hare [desert], etc.)

5. Abiotic – the nonliving things in the ecosystem. (ex: dirt, water, rocks, air, temperature, humidity, etc)

6. Biotic – the living things in the ecosystem. (ex: fish, frog, lily pad, cat tails, trees, whales, insects, etc)

7. Habitat - place in which organism lives. It provides food, shelter, & other resources organisms need to

survive. Organisms protect their habitat and fight with one another for the limited resources available.

a. More than one species can share a habitat. (ex: coral reef, tropical rainforest, field, etc – Many

different plants & animals live in each of these habitats)

b. More than one species can share similar habitats and food. (ex: shark and dolphin live in the same

habitat and eat similar food.)

8. A niche includes everything the organism does and everything it needs in the environment - place to live,

food, predators, other organisms around it, light, humidity, temperature, etc.)

a. Organisms can have more than one name to their niche. (ex: lion is a predator, consumer, and a

carnivore; a rabbit is a consumer, prey, herbivore, etc) b. Two species CAN NOT share the same niche. Over time, one species will die off because there

will not be enough for it to survive.

Energy Flow through the Ecosystem

9. Food chains, food webs, & energy pyramids show the FLOW OF ENERGY, not what eats what.

ARROWS POINT TO WHO GETS THE ENERGY.

10. Producer – makes its own energy through photosynthesis (ex: tree, grass, flower) – always at the

beginning of all food chains, webs, & pyramids. PHOTOSYNTHESIS IS THE FOUNDATION or

BASIS FOR ALL FOOD CHAINS, FOOD WEBS, and ENERGY PYRAMIDS.

11. Consumer – must eat to get the energy it needs to survive (ex: cow, human, bat, mouse, lion, frog) –

can’t make its own food through photosynthesis.

12. Herbivore – type of consumer that only eats plants. (ex: cow, horse, rabbit, grasshopper, elephant)

13. Omnivore – type of consumer that eats both plants and other animals. (ex: humans, bears, monkeys)

14. Carnivore – type of consumer that only eats other animals. (ex: owl, lion, frog, wolf, eagle, blue shark)

15. Decomposer – type of consumer that breaks down dead organisms and returns the nutrients to the soil.

(ex: earthworm, ant, mushroom, bacteria) – always last in the food chains and webs because they return

the nutrients to the producers completing the cycle.

16. Scavenger – type of consumer that eats dead, dying, injured, old, young, and other easy prey. (ex:

coyote, buzzards, hyenas)

17. 1 st order consumer/1 st level consumer – first consumer in food chain, web, or pyramid – a herbivore.

18. 2 nd order consumer/2 nd level consumer – second consumer in food chain, web, or pyramid – eats other

animals – either an omnivore or carnivore.

19. 3 rd order consumer/3 rd level consumer – third consumer in food chain, web, or pyramid – eats other

animals – either an omnivore or carnivore. Changes in a Population

20. Populations will INCREASE when: more births than deaths, more immigration

(moving in) then emigration (moving out), decrease in predators or competitors,

increase in food or prey, increase in habitat or territory, decrease in hunting by

humans, decrease in habitat destruction or pollution

21. Populations will DECREASE when: more deaths than births, more emigration

(moving out) then immigration (moving in), increase in predators or

competitors, decrease in food or prey, decrease in habitat or territory, disease

or natural disaster, increase in hunting by humans, increase in habitat destruction

or pollution

22. Limiting factors prevent population from growing beyond a certain point.

(ex: amount of food/prey available, amount of habitat/territory, weather conditions

– too cold / hot / wet / dry, predators, competitors, pollution, etc.

23. Carrying capacity is the maximum amount of a population an environment can hold – when the

population reaches this point there is no more food / space available and the population begins to starve.

Population numbers cannot increase beyond this point and stay.

Behaviors that Change a Population Size 24. Predator – animal that hunts down, kills, & eats another animal for its energy.

(ex: giant sea bass catching & eating a smaller fish; smaller fish hunting down and eating a sea urchin)

– herbivores can’t be predators

25. Prey – animal that is hunted down and eaten by another animal. (ex: the smaller fish that is eaten by the

giant sea bass; the sea urchin that is eaten by the smaller fish) - producers can’t be prey

26. Competitor – an organism that competes with another organism for a resource (food, water, shelter, etc)

or mate - can be two organisms in the same species or in different species. (ex: two lions competing for

a mate; a rabbit and mouse competing for the same shelter) – organisms at the same level in a food web

or energy pyramid compete with each other.

27. Symbiosis – close relationship between 2 different species of organisms where 1 organism lives near,

on, or inside the other and at least 1 organism is helped.

28. Commensalism – symbiosis where 1 organism is helped and the other isn’t helped or harmed – it

couldn’t care less about that animal being there. Examples: osprey hawk and the wren (little bird) or the

red-tailed hawk and the saguaro cactus.

29. Mutualism – symbiosis where both organisms are helped – two different species. Examples: algae and

coral, sea anemone and clown fish, blind person and seeing-eye dog.

30. Parasitism – symbiosis where 1 organism is helped and the other is harmed. Examples: tick and dog,

leech and human, tapeworm and dog.

31. Cooperation – two or more organisms OF THE SAME SPECIES working together to get what’s

needed. (ex: wolves hunt in a pack, bees taking care of the babies together)