Part of the Local Ecosystems Module Spotlight Biology Preliminary Text Chapter 4 Authors: D. Heffernan, J. Bastina, B. Grieve, K. Humphreys, A. Sartor Science Press 2002 Ecosystems Topic 3: Energy and Life

Energy and Life Because all heterotrophs depend on organic molecules they cannot make themselves, their lives are structured around the need to obtain them. Herbivores must live within reach of plants, carnivores survive only where there is prey and decomposers only exist where there are dead plants or animals. centralcoastwaterfront.com.au

Energy and Life Any conditions that influence the growth of primary producers in an ecosystem indirectly control the live of all other organisms as well. withfriendship.com

Energy and Life in a Rainforest On land, sunlight is virtually the same everywhere. Wildflower on Mount Kosciusko, grasses on the western plains near Dubbo and Saltbushes in Menindee all live in the same kind of light. There are seasonal variations but there is usually plenty of energy for photosynthesis. epiphanyofsunshine.wordpress.com

Energy and Life in a Rainforest In rainforests, sunlight varies from lots at the treetops to sometimes very little on the forest floor. For this reason, plants of rainforests have adapted to survive in widely different conditions of light intensity and water availability. earthobservatory.nasa.gov

Energy and Life in a Rainforest On the outer canopy, the light from the sun is very intense and there is no shortage of light. Because it’s a closed canopy very little light is able to penetrate and reach ground level. This is one reason why rainforest trees grow so tall and straight, they are competing for sunlight. daintreerainforestretreat.com.au

Energy and Life in a Rainforest Some vines cling to and climb tree trunks as they grow toward sunlight. Other plants such as orchids and ferns grow on tree trunks close to where the light is found. zeljkaderio.blogspot.com

Energy and Life in a Rainforest Plants that survive at lower levels have leaves adapted to survive low light conditions. You may have such plants around your house where they are not in direct sunlight. lamingtonnationalpark.net.au

Energy and Life in a Rainforest Animals have also adapted to survive in these different zones of light in forests. Pigeons and possums feed on fruits in the tree tops while cassowaries live on the forest floor and eat the fruit that falls from the trees above. australianmuseum.net.au

Energy and Life in a Rainforest The moist conditions on the forest floor ensure that decomposers rapidly return minerals of organic material back to the soil ready to be reused by the plants. wittenberg.nu

Energy and Life in the Sea Over two-thirds the Earth’s surface is covered by waster and more than half of the photosynthesis on our planet occurs in the sea. sciencedaily.com

Energy and Life in the Sea When thinking about light energy, the open-sea ecosystem is very different from terrestrial environments like forests. Sea water absorbs much more light than the atmosphere. This includes ultraviolet (short) and infrared (long) light regions of the spectrum. Coastal water also absorbs blue light because of the dissolved compounds carried into the sea by rivers and streams. art.com

Energy and Life in the Sea The further beneath the surface a marine organism lives, the less light reaches it and the greener the light is. Different wavelengths (colours) get absorbed by the water at different levels. Marine algae contain several different kinds of chlorophylls which each capture energy from different parts of the light spectrum. way-of-tao.com

A Little Side Track About Light in the Ocean The colours of objects are due to the particular wavelengths of light that they absorb and reflect. Therefore if the ocean water absorbs a particular wavelength of light, you won’t find anything below a certain depth in that colour. See website:

Energy and Life in the Sea Marine algae use other compounds called accessory pigments to collect more energy by taking in light that the chlorophyll does not absorb. For example, red algae are more common at 30 metres than brown or green algae. This extra energy can be used in photosynthesis, enabling the algae to grow at greater depths. purehealingfoods.com

Energy and Life in the Sea The region in which photosynthesis can occur may be as shallow as 30 metres in the turbid waters of the Antarctic or as deep as 200 metres in the crystalline waters of the tropical Barrier Reef. Only this uppermost part of the ocean can phytoplankton grow actively. Bottom-growing plants can grow only where the ocean floor is within this depth along continental margins. 123rf.com

Energy and Life in the Sea Below the surface layers are vast volumes of water in which darkness prevents plants from growing. However some organisms live at these great depths. These organisms get their food by eating other organisms or scavenging off the dead carcases that have fallen to their depths from above. 123rf.com

Energy and Life in the Sea Some play host to particular species of microbe that live inside their bodies and manufacture food by combining certain chemicals found in deep sea vent fluids with oxygen found in seawater. The microbes give some of the food they manufacture to their animal hosts

Homework 1. Contrast deep oceans with rainforests 2. How does energy reach animals on the floor of oceans? 3. How does energy reach animals on the floor of rainforests?