Tuesday, October 9, 2007
Day 3: Monday
Day 3: Today we woke up and headed back out to the Jurassic Park island which we found out is called Bastimento. We came back here to collect more Gecarsinus to use for our crab orientation experiments. This experiment looks at which way crabs orientate themselves when they interact with dark or light backgrounds. A table, labeled 0 to 360 degrees, is placed directly under a bright light and then a bucket is placed on the table. We set up the experiment in a dark room so that the crabs only see the light directly over them and are not affected by any shadows. The bucket has a cover on it with a hole drilled into the center and gong through the hole is a Tupperware container connected to a string running out of the bucket. This way, we can place the crab into the bucket, then put the Tupperware over the crab to calm it down and keep it in the center, then once the lid is on we can raise the Tupperware container up and the crab orientates itself. We used various strips of paper to simulate dark areas. Strips of paper covering 10 degrees then 30, 90, 180, and 350 degrees. We also used a strip of paper that looks like a burrow and recorded how the crabs orientated themselves to it. We will be testing the crabs all week and gathering as much data as possible to see how the crabs respond to the various targets. Later on in the week, we will also being soaking the target paper into different smells to see what affect this has on the way the crabs orientate themselves. Very cool stuff =)
So after collecting these crabs we again went out to the mangroves to do transects. We set up 5 transects, 30 meters long and used 1 meter squares to gather data. The beginning of the transect was placed right under the mangroves and then it went out into the turtle grass beds. inside the 1 meter squares we counted the number of sea stars, sea urchins, and sea biscuits as well as the number of mangrove leaves laying on the floor. Finally, inside a smaller grid (10 cm by 10 cm) we counted the number of shoots of sea grass and then number of leaves coming out of each shoot. This information will be utilized by a graduate student for her dissertation.
Lunch time came and went and then we ran some of the crab orientation experiments. After dinner we looked for some predatory crabs and hydrated the crabs that are stuck in the tortilla wheels. Poor things...at least they are getting some exercise. haha