From Plankton to Top Predator Building Marine Food

From Plankton to Top Predator: Building Marine Food Webs

(Almost) all life is based on the sun’s energy. § - Sunlight enters atmosphere. § - Plants turn sunlight into organic matter. § - This is called primary production. § - Energy flows in and out of the earth, but organic matter is recycled. From Energy Conversions to Food Webs

Plankton = Drifting, tiny life in the ocean Phytoplankton = Plant-like Plankton Primary Production = Biomass built from sunlight Primary Production = energy packaged into life

Life can also be based on other energy sources. § - Example: Hydrothermal vents. § - “Sulfide-reducing” bacteria § - “Chemoautotrophs” = primary producers that do not need sunlight. A cool exception! “Black Smokers”

Only a small portion of boimass is passed from prey to predator. § - Most of what you eat is respired, lost as heat, or pooped out. § - Example: Only 10% of the energy captured by plants is passed to caterpillars. § - 10% is an average – sometimes it an be higher or lower. The “ 10%” Rule

Trophic Pyramids Trophic = “nourishment”, “eating” Trophic levels 3 2 1 4 HIGHER LEVEL PREDATOR (1 KG) CARNIVORES (10 KG) HERBIVORES (100 KG) PRIMARY PRODUCERS (1, 000 KG)

Food Webs Decomposers Matter sinks away

Top Predators are at highest point in a food web. § - Nothing eats them (except decomposers) § - They eat many things. § - Farthest removed from primary production. § - Therefore fewer and smaller than the largest species in the food web. http: //earthref. org/SCC/ Top Predators: the Highest Trophic Level NSF GK-12: Scripps Classroom Connection

Relating Trophic Level to Size Top Predator Low Trophic Level

Relating Trophic Level to Size Top Predator Low Trophic Level

Relating Trophic Level to Size Low Trophic Level Top Predator

The Focus Question of the Lesson: § - Eating at low trophic level gives access to more of the sun’s energy. § - With more energy, you can be large and numerous. § - Top predators feed at high trophic levels, with access to small portion of the sun’s energy (because of the 10% rule). § - Therefore, top predators are not the largest and often rare. Why do the largest animals in a food web tend to eat the smallest things?

Conclusions § MOST LIFE IS BASED ON ENERGY FROM THE SUN. § THE 10% RULE MEANS HIGHER TROPHIC LEVELS HAVE LESS BIOMASS. § TROPHIC PYRAMIDS SHOW BIOMASS AT EACH TROPHIC LEVEL. § FOOD WEBS SHOW ENERGY FLOW THROUGH A GROUP OF ORGANISMS. § THE LARGEST MEMBERS OF A FOOD WEB ARE NOT THE TOP PREDATORS.