Hello, week 2 is now coming to an end and I am happy to say that I have a set research project. The question that I will be exploring is, how does the availability of alternative food influence cannibalism in the life cycle of Dungeness crabs? To give you a little background on the life cycle of the Dungeness crabs, their hatching occurs around January-March if they’re located in Oregon. In the first stage of their life cycle, they are called Zoea and go through six different phases (1 pre-zoea, 5 zoea) before entering the second stage and growing into Megalopae. To get to the Megalopae stage, it takes them about three to four months. In the megalopae stage, they are just a little under 1cm in length. They remain in the Megalopae stage for about a month, until finally becoming juveniles where they grow for two years before finally reaching sexual maturity as an adult crab.
My project includes crabs as megalopae, juveniles and adults. To test out their cannibalistic behavior, I will be having different aged crabs mixed with each other in separate tanks, some with an alternate source of food and others with no alternative. For example, in one tank I will place juveniles with megalopae, and in a separate tank juveniles with megalopae and mussels as an alternative food source. I conducted several quick and dirty experiments similar to that example this week to test and see quick results. Within 24 hours, all the megalopae that were in a tank with only juveniles, were completely gone; the juveniles completely devoured them. In a second quick experiment, I placed one adult crab with 10 juveniles and, within 24 hours, the juveniles were all gone. These two quick experiments basically showcased their cannibalistic behavior so to further explore that behavior, I created an experiment involving juveniles and mussels. The meaning of this experiment is to test that mussels are a food source for crabs, so that when crabs are given the choice of choosing food, they will either choose cannibalism or mussels. After 24 hours, this experiment ended up failing. Interestingly enough, when I came into lab this morning, the crabs that were feeding on the mussels were dead. Alan suggested that, the cause for their death was likely too much food leading to excessive decay and anoxia. The ratio of crab to mussel was too low, so I need to figure out a perfect ratio of prey to predator. In that experiment, I had about 10 grams of crab in the tank and 150 grams of mussels, which is 15 times the biomass of the crabs! Next week, I will be perfecting my experiments to help start my trials that will help test my hypothesis.
Outside of my research, this past weekend the other interns and I went on a boat trip to go dredging out in the ocean. Fortunately enough, I did not get seasick and thoroughly enjoyed the boat ride. This weekend we are camping at Cape Argo to go tide pooling early in the morning!
My name is Juan Flores and I am an intern in Alan Shanks’ lab. I am from a small city in the Los Angeles County, Pico Rivera, California. I will be transferring to the University of California, Santa Cruz in the Fall, pursuing a Bachelors in Biology.