The Flow of Energy

Learning Objectives Know that the initial energy source of almost all food chains is…. Know what Food Chains show Know what Food Webs show Know the labels for each level of a food web/chain Recognize how Pyramids can show levels of energy, mass, or consumers

The Sun by far has the most influence on life on earth The Sun provides the starting point for almost all the energy that life on earth eventually uses Pg 68 The sun is the starting point for food chains, food webs and energy pyramids (thanks to photosynthesis):

A terrestrial food chain Food Chains Quaternary consumers Tertiary consumers Secondary consumers Primary consumers Primary producers Carnivore Herbivore Plant Zooplankton Phytoplankton A terrestrial food chain A marine food chain Shows a single path of energy flow in an ecosystem Consumer/ Heterotrophs: must eat other organisms for food Producer/ Autotrophs: makes its own food  Pg 69

Food Chain: This picture properly shows the sun as starting point & decomposers (often bacteria and fungi) that break down dead material and recycle nutrients for producers to reuse

Food Webs Shows multiple paths of energy flow in an ecosystem (it’s several food chains put together) Pg 71

Food Webs Shows multiple paths of energy flow in an ecosystem (it’s several food chains put together) Simplified Version: Sea nettle Fish larvae Zooplankton Fish eggs Juvenile striped bass Pg 71

Smaller toothed whales Food Webs Humans Baleen whales Crab-eater seals Birds Fishes Squids Leopard seals Elephant Smaller toothed whales Sperm whales Carnivorous plankton Euphausids (krill) Copepods Phyto- plankton Shows multiple paths of energy flow in an ecosystem (it’s several food chains put together) Pg 71 More accurate version

Pg 71

Time for Pyramids, Pyramids and more Pyramids

Energy Pyramids Shows the “amount” of energy at each trophic level -Only 10% of the energy in any one level goes to the next, the other 90% is Used or lost as heat Pg 72

Energy Pyramids J = joule unit of energy Pg 72 Tertiary consumers Secondary Primary producers 1,000,000 J of sunlight 10 J 100 J 1,000 J 10,000 J J = joule unit of energy Pg 72

Biomass Pyramids Pg 72 Shows the “amount” of mass that gets transferred to each trophic level Your book implies, once again, that only 10% of the total mass makes to the next level up…

…in reality it is not usually so stable a % and in fact, while this is the most common shape of the biomass pyramid… (a) Most biomass pyramids show a sharp decrease in biomass at successively higher trophic levels, as illustrated by data from a bog at Silver Springs, Florida. Trophic level Dry weight (g/m2) Primary producers Tertiary consumers Secondary consumers Primary consumers 1.5 (14%) 11 (30%) 37 (4%) 809

Primary producers (phytoplankton) Primary consumers (zooplankton) …some rare aquatic ecosystems biomass pyramids can actually be reversed… Trophic level Primary producers (phytoplankton) Primary consumers (zooplankton) (b) In some aquatic ecosystems, such as the English Channel, a small standing crop of primary producers (phytoplankton) supports a larger standing crop of primary consumers (zooplankton). Dry weight (g/m2) 21 4

Pyramid of Numbers - Represents the number of individual organisms in each trophic level in one area Pg 73

Its been argued that eating meat is a relatively inefficient way of using photosynthetic production Worldwide agriculture could feed many more people if they all fed more efficiently, eating only plant material Trophic level Secondary consumers Primary producers End