Teachers Resources

Genetic Contribution Demonstration

This demonstration simulates how mussels reproduce. Mussel reproduction is dependent on the presence of a current to carry sperm from a male to a siphoning female mussel. Therefore, mussels can only reproduce if the female is downstream of the male mussel; the sperm cannot swim upstream. Somehow, the female mussel can differentiate between food, sperm from a different species of mussel (which is ingested or passes through her) and the sperm from a male of her species.

1. Ask for 2 volunteers. One will play a female mussel, the other a male.
   
2. Have the male mussel stand with his back to the female mussel. Give the male mussel a handful of confetti. The confetti represents his genetic contribution, or sperm. Instruct the male mussel that when you tell him it is time to spawn he will throw the confetti into the current (represented by the breeze created by the fan).
   
3. Have the female mussel stand about 5 feet behind the male mussel facing his back. Point out that the breeze coming from the fan represents the current and ask where the female mussel should be (upstream or downstream) in order to successfully reproduce. Instruct the female mussel that she will use her hands to "siphon" the sperm released by the male mussel. She cannot move her feet, but can move her hands to try and catch the males genetic contribution. She cannot pick up confetti from the floor.
   
4. Turn on the fan using the high setting for maximum breeze and tell the male to spawn.
   
5. Count the number of confetti pieces caught by the female mussel. Inform the female mussel that only the sperm caught is usable for reproduction. Point out that of the large number of sperm released by the male, only a very small percentage are actually successful in fertilizing an egg.