Allergy Tests. Guide. Allergy testing involves having a skin or blood test to find out what substance, or allergen, may trigger an allergic response in a person.Skin tests are usually done because they are rapid, reliable, and generally less expensive than blood tests, but either type of test may be used.llergy blood tests look for substances in the blood called antibodies. Blood tests are not as sensitive as skin tests but are often used for people who are not able to have skin tests. The most common type of blood test used is the enzyme-linked immunosorbent assay (ELISA, EIA).
Sensory Structures of a Flatworm. Flatworms live in many environments. Jupiterimages/Photos.com/Getty Images. Flatworms, also called planarians, belong to the phylum Platyhelminthes. Characterized by flat bodies, they have no circulatory or respiratory organs and a very simple digestive tract.This body plan limits them to very small, flat shapes to allow them to absorb oxygen and moisture.owever, a flatwormâs body contains the beginnings of more complex structures found in other animals. For example, eye spots resemble the ancestral forms found in more complex animals. Understanding flatworm sensory structures can help you understand the origins of these organs.
Planaria. Planaria (Platyhelminthes) are free-living flatworms that live in freshwater. They are typically found under rocks and debris in streams, ponds, and springs. Planarians are interesting to study for a variety of reasons. First, planarians have bilateral symmetry with two nerves extending the length of the body, an enlarged brain (ganglion cell), and two eye spots. The eye spots are sensitive to light. Planarians move away from the light and are most active in the dark. Second, light and water current can be used demonstrate kinesis (change of speed) and taxis (change of direction).