A Guide for the Study of Animals Part 31

2. What two protective habits has the earthworm? Name some other animals that have similar habits.

3. Describe the protective habits of the caddis-fly larva; of the leaf-roller moth. What benefit to the hermit crab is the colony of hydractinia growing on the snail sh.e.l.l which it inhabits? Give other similar cases.

4. Name as many cases of regeneration as you can.

5. What peculiar habits has a puss-moth larva? a dragon fly? Give other examples.

_Summary._

1. Name the various protective habits.

2. State any advantages or disadvantages you can with reference to these protective habits.

#E. DEFENSIVE STRUCTURES#

#Another Method of Protection from Enemies#

_Materials._

Specimens, charts, books, etc., to ill.u.s.trate the various defensive organs found among invertebrates.

_Observations and questions._

1. Describe the stinging hairs of the paramecium.

2. Describe the action and structure of nettle cells. Where are they located in the case of hydra; of jellyfish?

3. What defensive organs are found among the arthropods?

4. What are stinkbugs? What peculiar organs of defense have the caterpillars of the swallowtail b.u.t.terflies?

5. Where is the sting of a hornet located? To what in a gra.s.shopper does it correspond? Why does a hornet or bee inflict so painful a wound?

6. What peculiar organ of defense has a squid?

7. Find other examples of defensive structures.

_Summary._

1. What advantages have organs of defense as a method of protection?

2. What disadvantages?

#F. THESIS#

#To sum up the Important Points in the Study of Adaptations for Protection#

_Directions._

Write a connected account of what you have found out about protection of animals from their enemies, using the following outline:--

1. The struggle for existence--

a. its cause, b. its threefold nature, c. the various kinds of adaptations.

2. The various methods of protection from enemies.

a. The exoskeleton.

b. Protective coloration.

c. Animal a.s.sociations.

d. Protective habits.

e. Defensive structures.

CHAPTER VI

VERTEBRATES

#A. STUDIES OF FISHES#

THE LIVING FISH

_Vertebrates adapted to Water Life_

_Materials._

Living goldfishes or other fishes in small aquaria for individual study and a few fishes in a large aquarium where they have considerable freedom of motion.

_Definitions._

_Trunk_, the portion of the body between the head and the tail.

_Compressed_, a term used to describe the shape of the body when it is narrower from side to side than from dorsal to ventral surface.

When the opposite is true, the body is said to be _flattened_.

_Median fins_, the unpaired fins situated on the median line, dorsal and ventral, including the tail or _caudal_ fin, the _dorsal_ fin, and the _a.n.a.l_ fin.