environmental systems taks review session spring 2012 lecture 1 energy flow in ecosystems
TRANSCRIPT
Environmental SystemsTAKS Review SessionSpring 2012
Lecture 1
Energy Flow in Ecosystems
Movement of Energy
• Almost all of the life forms on earth get their energy from the sun and its light energy
Primary Productivity
• All photosynthetic (like plants) organisms take the light from the sun and convert it to chemical stored energy. This chemical energy is an organic compound (organic means having carbon).
Producers and Consumers
• All creatures and plants that create food with photosynthesis are called primary producers
• Creatures that eat the plants are called consumers
Trophic Levels
• Energy travels through the ecosystem and goes through levels.
• Each level is called a trophic level
Flow of Energy
• To understand the flow of energy lets say that when energy leaves the sun it is worth 100 dollars.
• Next when the plant makes food the energy is now worth 10 dollars
• When the rabbit eats the plant the energy is worth 1 dollar
• When the wolf eats the rabbit it is worth 0.1 dollars or 10 cents
Flow…
• So, as the energy moves through the ecosystem only 1/10th of it makes it to the next level!
The Trophic Levels
• The lowest level of the food chain is made up of the producers
• The second level of the chain is the herbivores (plant eaters)
• The third level is made up of the omnivores (eats plants and animals) and the carnivores (eats only meat)
Producer
Herbivore
Omnivore
Carnivore
The Special Case
• The Detritivores-worms, fungus, and bacteria-all survive by eating the dead things and returning the nutrients to the soil and air. If these creatures cause the decay they are called decomposers.
• They are on all trophic levels except the first
Energy
• As the energy moves from the producers to the herbivores, then to the carnivores, energy is lost in the form of heat.
• Because energy is lost, each level gets smaller (fewer # of organisms)
• For instance, there are more blades of grass than there are zebras and more zebras than there are lions.
Energy Pyramid
• Producers have the most members, then the herbivores have less, and the carnivores even less. This is because there is less energy available at each level. Think about it, there are many many plants (producers), many rabbits (herbivores), and few wolves (carnivores).
Pyramid of Energy
Biomass
• If we add up all the dry weight of tissue and other organic material in an ecosystem it is called Biomass
Pyramid of Biomass
Environmental SystemsTAKS Review SessionSpring 2006
Organism Interactions
Interactions among species
• 5 types of close interactions1.Predation
2.Parasitism
3.Competition
4.Mutualism
5.Commensalism
Predation – Co-evolution of Predator and Prey
• Tools: Predator – Improve efficiency at finding, capturing and consuming prey
Sharp Teeth Keen senses; sight, hearing, smell Strong, fast legs Camouflage
• Tools: Prey – Improve efficiency at hiding, evading and avoiding being eaten.
Sharp Teeth Keen senses; sight, hearing, smell Strong, fast legs Camouflage Spines Bad Taste / Warning Coloration / Mimicry
Predation – Co-evolution of Predator and Prey
Parasitism
• One individual benefits (parasite) while another is harmed (host).
Examples:
Ticks
Fleas
Tape Worms
Malaria
Parasitism – Co-evolution of Parasite and Host
• Tools: Parasite – Highly specialized physiologically and anatomically
Feeding apparatus Small size, hard to see Strong, attachment apparatus Natural pain killers at feeding site
Parasitism – Co-evolution of Parasite and Host
• Tools: Host – Defense Eyes, nose and mouth are
protected by tears, mucous and saliva
Grooming behaviors Natural body defenses
TAPE – WORM DIET!
Competition
• Use of a limited resource by two or more species
• Resources could be food (prey) or nesting sites, for example.
• Hyenas and Lions• Hawks and Eagles• Ducks and Geese
Commensalism
• When one species benefits and the other is not affected.
• Example: Bromeliads (Spanish Moss) grow on trees to obtain sunlight
• Barnacles on a whale• Birds that follow behind elephants and
eat the insects stirred up by the elephant