Making Mini-Aquariums
This activity sets up living aquaria which (if all goes well) will illustrate how an ecosystem constantly reuses the same materials (atoms), but does need something from outside - namely energy from the Sun.
Materials
- clear plastic saladbar containers
- empty 20 oz. plastic soda bottles (mixing chambers), w. caps, marked at 250 ml
- measuring spoons (.25 tsp and .5 tsp)
- brine shrimp (sold live at PetLand and other pet stores), and eggs
- algae (seaweed - from beach, or chloropsis from aquarium store)
- salts: NaCl, (and optionally, MgSO4)
- water
- (if available) microscope, perhaps camera and TV
- digital "slide show" of shrimps' life cycle
- molecule models to review past activities: (C, 2H, 3O; CO2, H2O; CH2O, O2)
Procedure
Start with a refresher of last week's activities by holding up the 6 basic atoms used. Ask "who can name a molecule we made? What does it look like?" When someone answers, hold up the molecule named, then get them to say what else with the remaining atoms of the 6. Then review: does Plant or Animal make these? Which one uses them? Go through the cycles.
Focus on "Plant", the "green being" - in the sea, it's actually algae (like seaweed). Let's make a living example! Students, working in groups, then start to assemble their own aquariums (recording each step in writing):
- make ~250 cc of salt water, containing ~9g (1.5 tsp) of NaCl and ~1.5g (.25 tsp) of MgSO4 (shake in bottles)
- put brine into salad container
- measure out (and record amount) chloropsis into container
Now it's Animal's turn (the "pink being"). Provide (e.g. on pieces of paper) samples artemia eggs, for naked-eye examination - see how tiny (especially the eggs, like dust). Then, if possible, show microscopic views via digital pictures on computer projector screen. Quickly tell the story of shrimp development, from hatching to adulthood.
Now students continue the aquarium setup:
- count out known number of shrimp and put into container
- seal lid on, put label on with number of shrimp and amount of chloropsis added
- draw resulting aquarium on lab sheet, as well as picture(s) of shrimp and written descriptions
- place some aquaria in Sunlight, others in the dark; observe and record over the following weeks
Meeting the components of our tiny ecosystem, then them all together into a mini-estuary for long-term study and care should (hopefully) naturally lead to feelings of protective fostering. This will set the stage for next week's consideration of conservation and stewardship.