1. EcoSystem Interactions Review

2. Energy, Producers, and Consumers
Organisms need energy for growth, reproduction, and metabolic processes.
No organism can create energy—organisms can only use energy from other sources.

3. Primary Producers
For most life on Earth, sunlight is the ultimate energy source.

4. Primary Producers
Primary producers are also called autotrophs because they use energy from the sun to change simple, non-living chemical nutrients (water & carbon dioxide) in the environment into living tissue during photosynthesis.
The term autotroph means “self-feeding”, therefore primary producers are able to make their own food.
Primary producers are the first producers of energy- rich compounds that are later used by other organisms.

5. Primary Producers
Primary producers store energy in forms that make it available to other organisms that eat them, and are therefore essential to the flow of energy through the biosphere.
For example, plants obtain energy from sunlight and turn it into nutrients that can be eaten and used for energy by animals such as a caterpillar.

6. Energy From the Sun
Photosynthesis captures light energy and uses it to power chemical reactions that convert carbon dioxide and water into oxygen and energy-rich carbohydrates. This process adds oxygen to the atmosphere and removes carbon dioxide.

7. Energy From the Sun
Plants are the main photosynthetic producers on land. Algae (phytoplankton) fill that role in freshwater ecosystems and the sunlit upper ocean.

8. Life Without Light
For some organisms, chemical energy stored in inorganic chemical compounds must serve as the ultimate energy source for life processes in the absence of light.
Biologists have discovered thriving ecosystems around volcanic vents in total darkness on the deep ocean floor.

9. Life Without Light
These deep-sea ecosystems depend on primary producers that harness chemical energy from inorganic molecules such as hydrogen sulfide.
The use of chemical energy to produce carbohydrates is called chemosynthesis.

10. Consumers
Also called heterotrophs because they must feed on other organisms to obtain energy
These organisms cannot make all the building blocks of living tissue from simple chemical substances available in their environment, and must rely on other things for food.

11. Types of Consumers
Consumers are classified by the ways in which they acquire energy and nutrients.
a. Herbivores obtain energy by eating autotrophs that have manufactured and stored proteins, carbohydrates, and other high energy substances
-Herbivores eat plant leaves, roots, seeds, or fruits.
-Common herbivores include cows, caterpillars, and deer.

12. Types of Consumers b. Carnivores obtain energy by eating other animals
- Carnivores kill and eat other animals, and include snakes, dogs, cats, and lions
Catching and killing prey can be difficult and requires energy, but meat is rich in nutrients and energy and is easy to digest

13. Types of Consumers
c. Omnivores are animals that eat both plants (autotrophs) and animals (heterotrophs). Humans, bears, and pigs are omnivores.

14. Types of Consumers
d. Scavengers are animals that consume the carcasses of other animals that have been killed by predators or have died of other causes. Vultures are scavengers.

15. Types of Consumers
e. Decomposers, such as bacteria and fungi, feed by chemically breaking down organic matter.
The decay caused by decomposers is part of the process that produces detritus—small pieces of dead and decaying plant and animal remains.

16. Types of Consumers
f. Detritivores, like giant earthworms, feed on detritus particles, often chewing or grinding them into smaller pieces. Detritivores commonly digest decomposers that live on, and in, detritus particles.

17. THINK ABOUT IT
What happens to energy stored in body tissues when one organism eats another?
Energy moves from the “eaten” to the “eater.” Where it goes from there depends on who eats and who is eaten.

18. Food Chains and Food Webs
Energy flows through an ecosystem in a one-way stream, from primary producers to various consumers.

19. Food Chains
A food chain is a series of steps in which organisms transfer energy by eating and being eaten.
Food chains can vary in length. An example from the Everglades is shown.

20. Food Chains
In some aquatic food chains, such as the example shown, primary producers are a mixture of floating algae called phytoplankton as well as attached algae. These producers are eaten by small fish, such as flagfish.

21. Food Chains Larger fish, like the largemouth bass, eat the flagfish.
The bass are preyed upon by large wading birds, such as the anhinga, which may ultimately be eaten by an alligator.

22. Food Chains
There are four steps in this food chain, with the top carnivore four steps removed from the primary producer. Producers are eaten by herbivores, which in turn are eaten by carnivores.

23. The direction of the arrow represents the flow of energy from one organism to another.

25. Food Webs
In most ecosystems, feeding relationships are much more complicated than the relationships described in a single, simple chain because many animals eat more than one kind of food.
A food web is a set of interconnected food chains by which energy and materials circulate within an ecosystem.

27. Food Chains Within Food Webs
Each path through a food web is a food chain.
A food web links all of the food chains in an ecosystem together.

29. Decomposers and Detritivores in Food Webs
Most producers die without being eaten. Decomposers must convert this dead material to detritus, which is eaten by detritivores, such as crayfish,shrimp, and worms.

30. Decomposers and Detritivores in Food Webs
The decomposition process releases nutrients that can be used by primary producers, similar to the way a recycling center works. Without decomposers, nutrients would remain locked in dead organisms.

31. Trophic Levels and Ecological Pyramids
Each step in a food chain or food web is called a trophic level.
Primary producers always make up the first trophic level.
Various consumers occupy every other level. Some examples are shown.

32. Trophic Levels and Ecological Pyramids
Ecological pyramids show the relative amount of energy or matter contained within each trophic level in a given food chain or food web.
There are three different types of ecological pyramids: pyramids of energy, pyramids of biomass, and pyramids of numbers.

33. 1. Pyramids of Energy
Pyramids of energy show the relative amount of energy available at each trophic level.

34. Ecological Pyramids
There is theoretically no limit to the number of trophic levels in a food web or the number of organisms that live on each level.
However, only a small portion of the energy that passes through any given trophic level is ultimately stored in the bodies of organisms at the next level.

35. Pyramids of Energy
Organisms expend much of the energy they acquire on life processes, such as respiration, movement, growth, and reproduction.
Most of the remaining energy is released into the environment as heat—a byproduct of these activities.

36. Pyramids of Energy
On average, about 10 percent of the energy available within one trophic level is transferred to the next trophic level.
The more levels that exist between a producer and a consumer, the smaller the percentage of the original energy from producers that is available to that consumer.

37. 2. Pyramids of Biomass
The total amount of living tissue within a given trophic level is called its biomass.
The amount of biomass a given trophic level can support is determined, in part, by the amount of energy available.

38. Pyramids of Biomass
A pyramid of biomass illustrates the relative amount of living organic matter at each trophic level.
Typically, the greatest biomass is at the base of the pyramid, as is seen in the field ecosystem modeled here.

39. 3.Pyramids of Numbers
A pyramid of numbers shows the relative number of individual organisms at each trophic level in an ecosystem.

40. Pyramids of Numbers
In most ecosystems, the shape of the pyramid of numbers is similar to the shape of the pyramid of biomass for the same ecosystem, with the numbers of individuals on each level decreasing from the level below it.

41. Pyramids of Numbers
In some cases, however, consumers are much smaller than organisms they feed upon.
Thousands of insects may graze on a single tree, for example. The tree has a lot of biomass, but represents only one organism.
In such cases, the pyramid of numbers may be turned upside down, but the pyramid of biomass usually still has the normal orientation.

42. Niches and Community Interactions

43. Tolerance
Every species has its own range of tolerance, the ability to survive and reproduce under a range of environmental circumstances.

44. Tolerance
When an environmental condition, such as temperature, extends in either direction beyond an organism’s optimum range, the organism experiences stress.
The organism must expend more energy to maintain homeostasis, and so has less energy left for growth and reproduction.

45. Tolerance
Organisms have an upper and lower limit of tolerance for every environmental factor. Beyond those limits, the organism is too stressed and cannot survive.
A species’ tolerance for environmental conditions, then, helps determine its habitat— the general place where an organism lives.

46. Tolerance
A species tolerance for environmental conditions, then, helps determine its “address” or habitat – the general place where an organism lives.

47. Defining the Niche
An organism’s niche describes not only the physical and biological environment where it lives, but how it uses biotic and abiotic factors in the environment to survive and reproduce.

48. Resources and the Niche
The term resource can refer to any necessity of life, such as water, nutrients, light, food, or space.
For plants, resources can include sunlight, water, and soil nutrients.
For animals, resources can include nesting space, shelter, types of food, and places to feed.

49. Physical Aspects of the Niche
Part of an organism’s niche involves the abiotic factors it requires for survival.
Ex> amphibians lose and absorb water through their skin, so they must live in moist places; if an area is too hot and dry, or too cold for too long, most amphibians cannot survive.

50. Biological Aspects of the Niche
Biological aspects of an organism’s niche involve the biotic factors it requires for survival, such as when and how it reproduces, the food it eats, and the way in which it obtains that food.
Birds on Christmas Island in the Indian Ocean, for example, all live in the same habitat but they prey on fish of different sizes and feed in different places.
Thus, each species occupies a distinct niche.

51. Competition
How one organism interacts with other organisms is an important part of defining its niche.
Competition occurs when organisms attempt to use the same limited ecological resource in the same place at the same time.

52. Competition
In a forest, for example, plant roots compete for resources such as water and nutrients in the soil. Animals compete for resources such as food, mates, and places to live and raise their young.
Competition can occur both between members of the same species (known as intraspecific competition) and between members of different species (known as interspecific competition).

53. The Competitive Exclusion Principle
Direct competition between different species almost always produces a winner and a loser— and the losing species dies out.

54. The Competitive Exclusion Principle
The competitive exclusion principle states that no two species can occupy exactly the same niche in exactly the same habitat at exactly the same time.
If two species attempt to occupy the same niche, one species will be better at competing for limited resources and will eventually exclude the other species.

55. Dividing Resources
Instead of competing for similar resources, species usually divide them.
For example, the three species of North American warblers shown all live in the same trees and feed on insects.

56. But one species feeds on high branches; another feeds on low branches, and another feeds in the middle.

57. Dividing Resources
The resources utilized by these species are similar yet different. Therefore, each species has its own niche and competition is minimized.

58. This division of resources was likely brought about by past competition among the birds.
By causing species to divide resources, competition helps determine the number and kinds of species in a community and the niche each species occupies

59. Predator-Prey Relationships
An interaction in which one animal (the predator) captures and feeds on another animal (the prey) is called predation.
Predators can affect the size of prey populations in a community and determine the places prey can live and feed.
Birds of prey, for example, can play an important role in regulating the population sizes of mice, voles, and other small mammals.

60. Predator-Prey Relationships
This graph shows an idealized computer model of changes in predator and prey populations over time.

61. Herbivore-Plant Relationships
An interaction in which one animal (the herbivore) feeds on producers (such as plants) is called herbivory.
Herbivores, like a ring-tailed lemur, can affect both the size and distribution of plant populations in a community and determine the places that certain plants can survive and grow.
For example, very dense populations of white-tailed deer are eliminating their favorite food plants from many places across the United States.

62. Symbioses
What are the three primary ways that organisms depend on each other?
Biologists recognize three main classes of symbiotic relationships in nature: mutualism, parasitism, and commensalism.

63. Symbioses
Any relationship in which two species live closely together is called symbiosis, which means “living together.”
The three main classes of symbiotic relationships in nature are mutualism, parasitism, and commensalism.

64. Mutualism
Mutualism – a relationship between two species in which both benefit
The sea anemone’s sting has two functions: to capture prey and to protect the anemone from predators. Even so, certain fish manage to snack on anemone tentacles.

65. Mutualism
The clownfish, however, is immune to anemone stings. When threatened by a predator, clownfish seek shelter by snuggling deep into an anemone’s tentacles.
If an anemone-eating species tries to attack the anemone, the clownfish dart out and chase away the predators.

66. Parasitism
Parasitism, relationships in which one organism lives inside or on another organism and harms it
Tapeworms live in the intestines of mammals, where they absorb large amounts of their hosts’ food.
Fleas, ticks, lice, and leeches, live on the bodies of mammals and feed on their blood and skin.

67. Parasitism
The parasite obtains all or part of its nutritional needs from the host organism.
Generally, parasites weaken but do not kill their host, which is usually larger than the parasite.

68. Commensalism
Commensalism- a relationship in which one organism benefits and the other is neither helped nor harmed.
Barnacles often attach themselves to a whale’s skin. They perform no known service to the whale, nor do they harm it. Yet the barnacles benefit from the constant movement of water— that is full of food particles—past the swimming whale.