Crab Night at Sligo Creek Elementary

Anna and Denise debunk the 'old guy in a lab coat' stereotype

How many eyes does a horseshoe crab have? How can you tell when a blue crab is about to molt? These questions (and more!) were answered by Anna and Denise last night at Sligo Creek Elementary School's Guest Scientist Series.

Hoards of eager young minds descended on the cafeteria to hear about what it means to be a scientist, discuss the similarities and differences between blue crabs and horseshoe crabs, and help run a science experiment. Kids and parents alike were surprised by some of the things they learned.

Take, for example, the fact that horseshoe crabs save lives. Including yours most likely. Denise explained that early vaccines were tested for bacterial impurities by injecting them into bunnies. If the bunny got sick, the vaccine was unsafe for people. But the famous blue blood of the horseshoe crab offered a different solution - a substance called LAL that clots when in contact with bacteria.
Using LAL from horseshoe crab blood, Denise demonstrated how modern vaccines are tested. For the control she added regular bottled water to LAL, and for the test she added bottled water that had been swished around in a volunteer's mouth and spit out. 

Denise leading the LAL experiment

In 15 minutes, the control was still a liquid and the test had congealed into a gel, just like it would for a vaccine that contains bacteria. Cool!

Anna taught the group how to determine when a blue crab's egg mass (or sponge) is about to hatch based on its color and how animals with hard outsides, like crabs, grow by molting.
Fun and informal presentations like this one make science accessible to everyone - great job ladies!