Naila :]

Naila :]

Wednesday, January 30, 2013

Web Surfing Science- Dichotomous Keys

Dichotomous Keys-

Why would you use a dichotomous key?
   To assist people with the identification of all types of living things.

What does dichotomous mean?
   The word dichotomous comes from dichotomy meaning branching, contrasting or opposite ideas. 

How does a dichotomous key work?
   A dichotomous key gives you a series of steps with a set of choices which are opposite or contrasting in nature that are initially very general and become more specific as one proceeds through the steps. By analyzing the physical characteristics of the object/organism in question and using the steps and choices given in the key, the observer can identify an object/organism based upon established traits.

What is the first step in making a dichotomous key?
   Start by observing the group of things to be used in the key.

What is the second step?
   List the most general traits that can be used to divide the organisms into categories.

How many choices should one have at each step decision point of the key?
   2 choices 

Identifying Pond Organisms-

Organism 1: Fingernail Clam
Organism 2: Tadpole
Organism 3: Pouch snail 

Identifying a Fish-

Fish:

1. band-tail puffer
2. spotted goat fish
3. glassy sweeper
4. squirrel fish
5. spotted eagle ray
6. peacock flounder
7. spotted moray eel
8. glass-eye snapper
9. trumpet fish

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