Experimento Artemia

Experiment: Plan and execute an experiment for a behavioral study with Brine Shrimp Artemia.

Research Question: Do brine shrimp artemia display positive phototaxis?

Design
Definition of the problem:
Artemia, better know as brine shrimp, are salt water crustaceans that forma part of the phylum Arthropoda (joint-legged invertebrates), class Crustacea. This specie measures aproximmatelyone centimeter in size (from 8 to 11mm) during their its adult life and are found specially in hypersaline and brine lakes. It is a very important source of food for different kinds of crustaceans and fish. According to different experiments, artemia seem to display an innate phototactic behaviour, meaning they move towards light. In this experiment, we will try to prove whether this statement istrue by puting a group of brine shrimp inside a tube which is illuminated on the left side, while it is totally dark in rightside; and we will see where do they go to.

Variables:
1. Dependent: Number of artemia moving towards the illuminated or dark side of the tube.
2. Independent: Lighting on each side of the tube (left side =light and right side =dark)
3. Controlled: All thevariables needed to be kept constant so that the experiment was always performed under the same circumstances:
* Light intensity: the intensity of light from the light bulb has to be the same every time the experiment is repeated (25 watts)
* Light from background: the experiment has to take place in an enclosed space where there is no external natural (sunlight) or artificial (other lamps)illumination apart from the 25 watts light bulb.
* Temperature: the different repetitions of the experiment are done during a short period of time and in the same room so that temperature remains constant.
* Inclination of the tube: The position of the tube will be horizontal all the time (to stop influence from gravitational gradient as far as possible).
* Movement of the tube:movement has to be avoided at all moments so that artemia are not disturbed.
* Distance of object: the tube always has to be placed at the same distance from the lamp (15 cm).
* Noise: A silent environment is ideal because we do not know the influence of noise on artemia.
* Number of brine shrimps: For every repetition, 100 artemia will be placed inside the tube (and always the same ones)* Age and specie: all the brine shrimps have to belong to the same specie and have to be relatively young artemia.
* Time: three repetitions will be made, each will last 5 minutes so that results can be fairly compared)
* Person: the person or people counting the brine shrimps have to be preferably the same during each repetition and they have to be capable of doing it correctly.Method to control the variables
* Test tube (20x150mm)
* Pipette
* 300 brine shrimps (same age)
* Attachabale plastic
* Small piece of black cloth ore carton (3x3cm)
* Test tube holder.
* 25 watts light bulb
* Closed room with curtains
* Water for artemia
* Ruler
* Extra recipient to divide artemia

Method and collecting of data:
1. Poor some water(with artemia) inside a recipient in a room with curtains closed.
2. With a pipette, take slowly 10 artemia (count one by one) from the recipient and poor them inside the test tube. Repeat this 10 times until you have 100 brine shrimps and the test tube is full of artemia water (try to leave the fewest amount of air possible inside).
3. Wrap the tube with the attachable plastic (so that thewater does not fall out) and cover exactly half of it with a black cloth.
4. Place the test tube horizontally (180 degrees from table) on the test tube holder.
5. Place a 25 watts lamp 15 cm from the tube and turn its light on.
6. Leave the test tube there for 5 minutes. Do not stand very close to the tube.
7. Two people have to count together how many brine shrimps are on the...