Brine Shrimp: Hatch the Excitement

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Sea monkeys - the popular pet of the 1960s and 70s.  They allowed kids to see “instant life” which is what the founders originally called their product when released in 1957.  Students are still fascinated by these creatures and they lend themselves well to excitement in the classroom.


Introducing the Lesson - 

I show students a video of brine shrimp under the microscope.  While watching they make observations, inferences and ask questions - anything besides what are they?


You can certainly just hatch some brine shrimp and let the kids look at them under the microscope, but I like to put a scientific spin and make it a little more.  This is my student handout, and all my teacher tips are below.  


Material Notes - 

  • De-chlorinated water: My husband is a big fish tank enthusiast so I use his reverse osmosis water, but you can just get water from the tap - just leave it out a few days before use.

  • Salt: Again my husband comes in handy with these fish tanks and we have endless amounts of aquarium salt.  You can pick some up at the pet store, order online or even just purchase non-iodized salt at the grocery store.

  • Water bottles: I just save plastic water bottles and rinse, any kind will do.

  • Brine shrimp eggs: These can be found at the pet store or ordered online.  Keep in the fridge and they will last for a LONG time.  You need to add so little to each bottle; these eggs are so small!


Setting Up the Experiment - 

Students should set up the experiment using the following procedure - 

  1. Use masking tape to label the bottles A, B, C and D.

  2. Use a graduated cylinder to measure and fill each bottle with 250 ml of de-chlorinated water.

  3. Add the following amounts of salt to the indicated bottle – 

A: none, this will be fresh water

B: ¼ teaspoon

C: ¾ teaspoon 

D: ½ tablespoon

  1. Cap each bottle and shake to dissolve all of the salt.

  2. Bring your bottles to your teacher and they will add equal amounts of brine shrimp eggs to each of your bottles. DO NOT CAP YOUR BOTTLES!

  3. Set your bottles together on the side counter and lay a piece of paper with your group member’s names over all of the bottles. 

  4. Make your initial observations.  We will observe the containers for the next two days.


Here is a link to a basic slide that you can display with these instructions.


Making It More - 

After set-up we work as a class to develop a question that we will be able to answer as a result of setting up this experiment and the observations that we will be able to make over the next 2 days.  You do not have to do this over 2 days - if you want to speed up the hatching process put your bottles in a nice warm location.


Students then make a hypothesis.


This is a good time to go over and/or practice microscope skills that the students will need to view brine shrimp up close in the next few days.


Observations - 

Before removing any samples students should make observations and rank the bottles from lowest to highest hatch rate.


Students can take samples from their bottles using a dropper - just be sure that the opening is large enough to accommodate the shrimp.  Cut your dropper if needed.  I encourage students to look in their dropper for a shrimp before placing it on a slide or even better a tray from my disposable contracts; this is avoid lots of water everywhere with no shrimp!

Once they have a shrimp on the slide or tray it's time to bring them to the microscope.  On basic student microscopes 4x is usually great, 10x works but can be narrow so the shrimp swims out of view often.  Stereoscopes are also an option here since the shrimp are visible with the naked eye.


Finishing It Off - 

If you are doing a second day, keep the bottles.  On day two I have students see if there was any die off or further hatching.  They can use microscopes again but it is not necessary.


If you are finishing after day one, I have the students empty bottles of living shrimp into a container that I feed my fish.  Have them rinse their bottles because these are definitely reusable.  They can then answer the lab questions.  Depending on the level of experience your students have in experimental design there may need to be conversation of independent and dependent variables.

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