How To Study Living Animals


Definitions.

Postembryonic development,

the changes taking place in the development of an animal after birth or hatching herunterladen.

Larva,

the active feeding stage. It is the first stage in postembryonic development, and follows the gastrula stage.

Pupa,

usually a resting or quiescent stage herunterladen. It is the stage following the larva stage.

Observations.

1. Describe the appearance of the egg packet both as seen with the unaided eye and with a hand lens microsoft office kostenlos downloaden vollversion deutsch chip. Find the trapdoor.

2. What is the difference between the appearance of the larva and the pupa? How do their resting positions differ?

3. What does the larva do when disturbed? Describe any characteristic motions that you notice.

4. Contrast the pupa with the larva under the same conditions and note any differences.

5. Where do you think the external openings of the respiratory organs of the larva and those of the pupa are located? Give reasons for your answer.

6. Into what does the pupa change? Where must the pupa be at this time? Is it easier for the pupa to stay at the surface or at the bottom?

7. Examine an adult mosquito. State the kind of mouth parts, the number and appearance of the wings, the appearance of the antennæ. How does the male and female differ in this respect?

Suggested drawings.

a. A diagrammatic drawing representing the jar of water and showing the various positions assumed by the wrigglers.

b. Careful drawings of each stage.