How strange to call this planet 'Earth' when quite clearly it is ocean. Arthur C. Clarke

Tuesday, September 20, 2016

Which Would a Whelk Want?

This summer I had the opportunity to mentor a high school student on a science project. She spent 10 weeks learning about the research process, building and running an experiment, and analyzing the results. Here is a quick summary of what we did. I say we, but she really did most of it.

Main question: Do dogwhelks use olfactory cues (smell) to detect prey?

Hypothesis: If dogwhelks are placed in a divided chamber, they will be more likely to move toward the side with a prey item.

Method: We built divided chambers and set them up under running filtered seawater. We randomly placed one mussel on one side of the divider. We then put one hungry dogwhelk on the opposite end of the chamber and recorded its movement until it crawled to one side of the divider.  We repeated this several dozen times.

The control trial is on the left, where we tested if the dogwhelks
are inherently predisposed to go on one side or the other. They 
were not, so we proceeded with the prey experiment. Once the 
dogwhelk crossed the red dotted line, we recorded which side
of the divider it was on.

Dogwhelks in position at the beginning of a trial.

Dogwhelks at the end of a trial.

Main result: Dogwhelks chose the side with the prey significantly more than the empty side. They seem to be using smell to find their food. 

Discussion: In today's warming and acidifying ocean, organisms' ability to use chemoreception is often altered. Dogwhelks are important predators in their habitat, and if they are going to have a tougher time finding or choosing their prey, their impact on the habitat will change, possibly changing the ecology of the prey community. For example, if dogwhelks stop eating their preferred species of prey, e.g. the blue mussel, this species may become more abundant and compete more with others.