Activities

Learning statement: Organisms are designed for specific feeding methods. Why are we considered carnivores? Our body design, particularly limbs and teeth function effectively for most of the foods we eat.

Goal: Students will be able to describe three attributes that determine what type of food we are designed to eat.

Objective 1: Students will be able to describe three methods of obtaining food: scavenging, filter feeding, and hunting

Objective 2: Students will list at least two reasons why humans are not considered scavengers; list two animals that are scavengers.

Objective 3: Students will list at least two reasons why humans are not considered filter feeders; list two animals that are filter feeders.

Activity 1: Scavenging food

Materials: Cookie baking sheet, waxed paper or aluminum foil, graham crackers or crumbs, mallet, drinking straws, paper plates, peas or other large seeds

Preparation: Place paper or foil on cookie sheet; place graham crackers on sheet and cover with paper/foil.

Pound crackers until they are finely ground.

Place graham cracker crumbs and sprinkle the seeds on individual plates, and give each student a straw.

Students suck crumbs through their straw until their plate is clean. They should avoid the seeds so they don't clog the straw. Older children should not use their hands to move the straw across the plate.

Explanation: Scavengers in the ocean often get nourishment by sucking sediment in and processing organic material. Non-nourishing material is processed through and eliminated as waste. Trilobites ate in this manner. Sea cucumbers have (and still) use this method and are one of the most prolific invertebrates in the ocean today. There are sediment particles and organisms that are too large to be consumed by the scavenger.

Discussion: Why are we not adapted to feed as scavengers? What characterstics do scavengers share?

Activity 2: Filter feeding food

Materials: Popped pop corn, circulating fan elevated on a table top, protective eyewear, baseball gloves (optional). This activity may be done outside if there is access to an electrical outlet.

Preparation: Students should be spread out so they are just beyond hand-to-hand with their arms outstreatched (baseball gloves optional). Some students should sit on the floor, others should stand behind them. Use a circulating fan set on its highest setting and gently pour pop corn directly in front of the fan so it sails through the air. (You may want to practice without students first, so you can place them at the proper distance.) Students can move their arms (but cannot move their body) up and down /back and forth, but cannot grab pop corn that is beyond their grasp. They can either eat any pop corn they catch or hold and count it (i.e. on a paper plate) in order to see who caught the most food. To prevent choking, discourage students from catching pop corn with their mouth.

Explanation: In the ocean, filter feeders depend on ocean currents to bring food to them. Organisms have have developed several methods to catch microscopic plankton. Corals have tentacles covered with stinging cnematocysts that harpoon and paralyze their prey. Crinoids and basket stars have sticky arms with cilia that move food toward their mouth.

Discussion: There are no air borne filter feeders, but many plants and fungi are pollinated and disperse seeds or spores by the wind. Imagine trying to catch food floating through the air! What characteristics do filter feeders share?