Energy Production In their daily struggle for survival marine animals perform a variety of activities e.g. movement - squids and octopuses use jet propulsion, scallops clap their shells and fish swim. Energy is required to perform all of these activities, however, unlike plants who can photosynthesis (see activity 2) to produce energy animals get their energy from food. Food provides nutrients for animals, i.e. proteins, sugars, starches, fats, vitamins, minerals and water, which allows them to maintain their energy level to carry out their essential daily routines. Animals break down and utilize these nutrients through a process known as metabolism. Cells of living organisms are composed of proteins, carbohydrates and fats (lipids) which they obtain from the food which they consume. Proteins are made up of building blocks called amino acids. When these amino acids join together within the animal cell the result is growth. Sugars and Starch provide a quick energy release to organisms - together these nutrients make up carbohydrates. An example of a simple sugar compound is glucose (C 6 H 12 O 6 ). When glucose is not being used in the body it is changed into, and stored as starch. Starches can be changed back into glucose when the body needs energy through a chemical process known as hydrolysis. Hydrolysis is a breaking down process and occurs when food is digested. Marine plants obtain the minerals they need by absorbing the minerals from the surrounding water. Marine animals that eat marine plants absorb the plants minerals into their body tissues. Water is the most abundant nutrient in most living organisms - with on average about 80% of an organism s weight being water. Water contains and transports many dissolved substances within the body. Water is also necessary for chemical reactions such as photosynthesis to occur.
Food Chain All organisms on Earth survive by participating in a Food Chain and a Food Web. Food chains and food webs show the transfer of energy from the sun to the producers, (e.g. seaweeds), which in turn transfer their own food to consumers (e.g. marine animals). Food chains therefore describe the eating relationships between species within an ecosystem. A marine food chain is made up of: 1) Primary producers: make their own food. These organisms are typically photosynthetic and are also commonly known as autotrophs, where they produce simple organic substances (essentially "food") from an energy source and inorganic materials. Example: phytoplankton, seagrass, zooxanthellae. 2) Consumers: obtains food by eating other organisms. Example: Starfish, sponge, shark. A) Primary consumers: Organisms that get their energy from organic substances by eating only producers are called heterotrophs. Heterotrophs include herbivores, which obtain their energy by consuming live plants. Example: Manatee, limpet. B) Secondary consumers: these mainly include carnivores, which obtain their energy from eating primary consumers. Example: Shark, octopus, sea otter. C) Tertiary consumers: those animals that feed on secondary consumers including the omnivores i.e. detritivores, scavengers and decomposers, which all consume dead biomass (both consumers and producers). Example: Basking shark, sponge, coral, crab. Typically, the highest level upon which a consumer feeds determines what it is called, even though it may feed on more than one level.
Energy Transfer Organisms in a food chain are grouped into trophic levels, based on how many links they are removed from the primary producers. At the very first level are producers (plants) and these are the most important part of the chain. Without producers, the chain would collapse, and all animals above would starve and perish! Blue whale At each level of the food chain, about 90% of the energy is lost in the form of heat. The total energy passed from one level to the next is only about one-tenth of the energy received from the previous organism. Therefore, as you move up the food chain, there is less energy available. Animals located at the top of the food chain need a lot more food to meet their energy needs. Copyright www.pixel-lab.ie Krill Copyright wikipedia Biomass: The total amount of organisms per unit volume, of carnivores is much less than that of herbivores they consume. Similarly the biomass of herbivores will be much less than the total weight of plants they consume. For example: a hundred tons of plants would produce only about 10 tons of herbivores, which would in turn feed and sustain only one ton of carnivores. As you move up levels in the food chain, biomass decreases. Plankton Basic food chain of the baleen whale (Blue whale) The transfer of energy is complete when both the producers and consumers die and their remains are consumed by scavengers. The end of a food chain or web occurs when decomposers such as bacteria break down dead plants and animals as well as wastes.
Food Web A diagram illustrating showing a Food Chain within the Food Web A food chain becomes complicated when other animals get into the picture and create a food web. A food web is a network of food chains that are linked together. For example, krill are not only eaten by whales but are also eaten by other fish, penguins and seals. The baleen whale may also be eaten by the killer whale. In this case the killer whale would be at the top of this food web. A food web follows a natural order i.e. plants or animals at the lower levels are consumed by animals higher up the chain. If a plant or animal at lower levels begins to die out or disappear, then animals higher up would also begin to die from lack of nourishment. There are a number of causes for a break in a food web e.g. 1. Disease or sudden weather changes can alter the biomass of particular plants, or animals such as zooplankton. These are both natural phenomena and a food web will usually recover form such occurrences. 2. The world s fishing industry, however, is something that could destroy the ocean s food chain if not monitored. If the fishing industry began wiping out lower levels of the food chain, they would upset the natural balance of marine life.
Quick Test Match each description with the correct term in each section. Write the letter on the line provided 1. plant and animal eater A. Tertiary consumers 2. Eat primary consumers and sometimes producers B. Herbivores 3. Plant eaters C. Secondary consumers 4. Eat only producers D. Omnivores 5. Animal eaters E. Primary consumers 6. Eat secondary consumers, and sometimes primary consumers and producers F. Carnivores
Quick Questions On a separate page write the answers to these questions and create your own food web. 1. What are some of the causes for a break in the ocean s food chain? 2. How might a break in the ocean s food chain affect us? 3. How is a food web different from a food chain? 4. Define 4 of the following terms: A) Biomass B) Phytoplankton C) Omnivores D) Hydrolysis E) Metabolism F) Trophic Levels G) Protein 5. Create your own Marine Food Web mural and show three possible food chains within your food web. [For each animal or plant used show what each depends upon by drawing an arrow from each animal or plant to what it depends upon].