For You To Do - Teaching Suggestions and Sample Answers

Part A: Observing Animal Diversity
1. Establish with the students your guidelines for handling live animals.
The following are concerns you may wish to discuss with your students.
All animals must be treated as humanely as possible. Avoid bringing wild animals into the classroom. Obtain healthy animals from pet stores or biological supply houses. Earthworms may be an exception, but do return any earthworms you collect to their natural habitat after your observations. Be sure that the proper environment can be established in the classroom for any live animal you use. Under no circumstances inflict any pain or injury on the animal. Avoid loud and startling noises.

Review all the safety tips provided in the student text. Stress the importance of washing hands and avoiding any contact with the mouth and eyes. Frogs can harbor Salmonella. Hermit crabs can grasp tightly; warn students to keep their fingers away from the pincers.

Teaching Tip
To help students understand the different types of symmetry, ask them to classify a number of familiar items as having either radial or bilateral symmetry. For example: what type of symmetry does each of the following show: a baseball bat (radial); a garbage pail (radial); a chair (bilateral) and a spoon (bilateral).

The following data table contains possible observations that the students may make, although the observations are presented in a more scientific language than you would expect of your students. The italicized sections provide additional information for the teacher. Encourage students to make their own observations and express them in their own words. Note in Step 3, students are advised to “Record only your own observations, not what you have read or heard.” As you visit the stations, avoid the temptation to provide additional information, instead use suggestions that will develop the students’ observational skills

Part B: Animal Adaptations to the Environment
1. a) Student answers will vary. Some possible answers are provided.
Hydra

Feeding–tentacles are capable of working together to capture food
Gas exchange–hydra are only two (germ) layers (ectoderm and endoderm)
thick, therefore each cell is in contact with water and oxygen is able to diffuse into each cell
Movement–hydra have nerve and muscle tissues that enable them to move

Feeding–a digestive system is present for digesting food
Movement–a nervous system permits more complex movement and the planarian can move about freely
Gas exchange–the planarian is small and lives in the water where oxygen is free to diffuse into and out of each cell

Movement–the shape of the earthworm is ideal for burrowing through the soil; bristles along the underside of the earthworm help in its movement along and through the soil
Feeding–the “brain” and the mouth are at one end of the earthworm
Gas exchange–oxygen diffuses through the skin as earthworms burrow through moist soil

Movement–jointed legs enable the crab to move freely
Feeding–claws are able to grasp prey; eyes can see prey
Frog
Movement–strong muscular hind legs are used for jumping; feet of hind legs are webbed for swimming
Feeding–a long (sticky) tongue is used to capture prey
Response to danger–large eyes are able to move to see any “enemies” (predators)

Teaching Tip
Students often think of an ecosystem in terms of the living or biotic components. They must appreciate the significance of the abiotic components as well.
Each ecosystem has a particular set of abiotic factors. These influence the biotic factors that exist in an ecosystem. Abiotic factors include: temperature, water, atmosphere and wind, fire, gravity, topography, and geological substrate and soil. Discuss with the students how each factor affects the biotic factors. For example, most species of organisms are limited in the range of temperatures in which they can survive. Water is one of the most important factors because it is essential to living things. The carbon dioxide required for photosynthesis and the oxygen required for respiration come from the atmosphere. Fire can be destructive, but it can also rejuvenate an aging forest. Many structural adaptations of plants and animal are related to overcoming the pull of gravity.