How To Study Living Animals


Summary.

1. Name four uses of color.

2. Name four ways an animal is protected by being like its background.

3. Name one way it is protected by being unlike its background.

4. What disadvantages in this method of protection?

C. Animal Associations

To show Another Method of Protection from Enemies

Materials.

Specimens, charts, etc., illustrating animal associations herunterladen.

Definitions.

Animal communities,

associations of many animals of the same species in communities in which there is a greater or less division of labor.

Gregarious,

associations where there is but little division of labor.

Parasitism,

an association where one animal lives at the expense of the other. The animal on which the parasite lives is called the host. If there are two hosts during the life cycle of the parasite, the second host is called an intermediate host herunterladen.

Symbiosis,

an association where two animals live together in mutually helpful relations.

Commensalism,

an association where two animals live together in relations not mutually helpful but without injury to either.

Observations and questions.

Note.—To find answers to many of these questions it will be necessary to refer to the reference books in the laboratory.

1. Examine a specimen of Volvox. Why may this be considered a colonial protozoan and not a many-celled animal? What is gained by the colonial habit microsoft office kostenlos downloaden vollversion deutsch chip?

2. Is the colonial habit common or rare in sponges and cœlenterates? What is chiefly gained?

3. Describe the community life in one of the insects in each of the following groups:—

a. ant, honeybee, termite.

b. bumblebee, paper wasp, hornet.

c. mining bee.

d. carpenter bee, mud wasp, digger wasp.

4. Name the host or hosts in the following cases: trichina, liver fluke, malarial parasite, tapeworm, hook worm. Give the life history of one or more of the parasites just enumerated. What is the effect of parasitism on the structure of the parasite?

5. What is the relation between ants and plant lice? Show how this relation is mutually helpful. Mention other cases of symbiosis that you have come across.

6. With what animal are barnacles often associated? What is the habit of the pea or oyster crab? What are “guest bees”? What structure is lacking that is found in other bees? What are often found in the cavities of sponges? Why are these associations called commensalism rather than symbiosis?

Summary.

1. Into what groups can animal associations be divided based upon the number of species concerned?

2. From the standpoint of protection, is this a good or a bad method of protection?

3. What disadvantages can you see in this method of protection.

D. Protective Habits and Powers
Materials.

Specimens, charts, and books, showing habits of invertebrates.

Definitions.

Regeneration,

the power to grow new parts of the body when parts have been lost or injured.

Masking,

the covering of an animal by some object or organism so as to hide its identity.

Nocturnal habits,

the habit of hiding in the daytime and coming out at night to feed.

Terrifying attitudes,

the protective attitudes assumed at times by animals in order to ward off attack.

Observations and questions.

1. How are Sabella and Serpula protected? What advantages and disadvantages in this habit? What changes in structure are associated with this tube-dwelling habit?

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 shell 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 illustrate 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 butterflies?

5. Where is the sting of a hornet located? To what in a grasshopper 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.

. The exoskeleton.

a. Protective coloration.

b. Animal associations.

c. Protective habits.

d. Defensive structures.


CHAPTER VI
VERTEBRATES

A. Studies of Fishes