Eating is a crucial part of our daily lives and if we were to start cutting back too much on it, there would be negative consequences to the health of our bodies. Imagine you’re a single parent with five kids, all below the age of 10. If you were to stop eating properly and lose the energy to cook dinner, give your kids a shower, or play with them, your kids would be suffering because of your lack of eating. They depended on you to eat and stay healthy so they could get the necessities they needed in order to survive.
Getting back to invertebrates, if a species which plays a vital role in providing nutrients to other species or keeping the environment around itself free of bacteria and toxins, were to reduce its function, many other species which were dependent on it would suffer. A species which plays such a role is the mussel. It uses its ability to efficiently filter feed to purify water and recycle nutrients that other species in the surrounding water column can use. Mussels take up water through one siphon and release it through another siphon. In this process, they are able to absorb the nutrients out of the water they need and spit out what they don’t want. However, the food they spit out is high in nutrients that other species can use.
My independent project focused on the effects that two different predators, a sea star (Pisaster ochraceus) and a snail (Nucella lamellosa), have on the feeding of a mussel (Mytilus trossulus). What is important to note is that I was not focusing on the effects that would occur if the predator ate the mussel, but instead the indirect effects it can have on the mussel with its chemical cues. I set up the experiment as shown below with a control tank, a sea star tank and a snail tank. I also added algae cells in each tank so I could see how much algae the mussels consumed over a 30 minute period.
What I found after using a cell counting machine (also shown below) was that the mussels that were exposed to either predator ate a lot less of the algae cells compared to the control tank where there was no predator present.
So now that we know that mussels don’t filter as much when they are exposed to a predator, we can see how it is likely that the water surrounding an area which has a lot of mussels that have started to filter less will not be as purified and will not have enough nutrients for other species to use. This is a big problem!!!!!!!!!
Here is a YouTube link to a video which sped up the feeding process of mussels so it is possible to see how they feed. Pay attention at 0:23 where they show the mussels spitting out the food they don’t want, pretty cool!