Saturday, July 31, 2010
group 2 post
okay, so today we went to the barking crab to look at sea life in the harbor. I was late because I didn't read the email and was wondering around aimlessly for an hour. Sorry Prof. Berman! the first observations I made were that on the northern side of the dock at long wharf, there were some birds flying around and we noticed some different types of growth in the inter tidal zone on the pilings. I noticed a dark seaweed looking plant towards the bottom on the inter tidal zone that had small pockets on the end that appeared to be filled with something. I later discovered that these were filled with air and because of their shape and size, I have hypothesized that the plants were rockweed. I also believe this because the field guide said it was one of the most common plants in this area and because prof. berman accidentally let the name slip; thus giving me a hint. We then noticed that there was less growth on the pilings that were covered in shade by the harbor towers and we hypothesized that the shade prevented sufficient photosynthesis to have the same growth as at long wharf. The water was reasonably clear all along the harbor walk but became more cloudy at the barking crab. there was an oily substance on the surface of the water at our dock which was dock B7 ( the second to last dock)
we determined the water temperature to be 71 degrees Fahrenheit at a depth of 15 feet 7 inches which was 3 feet from the ocean bottom. We also recorded a surface water temperature of 74 degrees Fahrenheit indicating that the surface was warmer. the depth of the water was 18 feet 7 inches. We then leaned over and pulled the growth under the docks up for examination. Ted posted some of our groups pictures below. (he is a great photographer) The first thing i noticed was a clam like animal that I have known to be an mussel. I did not know what type this was, however, and the field guide said that a dark blue to black looking mussel that grows in the region in urban settings would likely be a Blue Mussel. Blue mussels are common in the area, grow in groups, and have a shiny inside, much like the ones I observed. I further hypothesized that the fuzzy plants that looked like little less than one inch long trees were coralline algae. Coralline algae is typically found on blue mussels in urban settings and this is exactly where I found the unknown plant. It was less than one inch long, green in color, abundant on the mussels, and had very small branches. I then noticed the small, hard, white, shell like creatures on the dock that looked like barnacles. judging from their size and number of openers (4) and color, I believe them to be rock barnacles. Although this is a very weak hypothesis because I couldn't see them too well.
next, we found a crab. this crab was not more than an inch wide and had 8 legs and two claws. the 3 spikes on the side of each of its eyes, an opaque color on the ends of its legs, and its clear underside and brown/ blue top makes me think it is a green crab. I ruled out the mud crab because mud crabs have little flipper legs in the back and I did not notice these on our crab.
next we saw the small sacks that had the flowers in them. I had to go online to find the answer to this one, but I want to say that these were Golden Star Tunicates. These organisms are approximately 2 inches in size and grown on slow moving objects like docks or mussels. I read the other posts and realize that some disagree with me, but my thinking is that these best match what I saw
Next we saw a one inch long, twig like animal that was pink in color and had approximately 8 legs in different locations. As a group, we talked about it and from pictures, determined this to be a long horned skeletal shrimp. These have been known to be found under docks among other forms of sea life and are generally this size and color.
Next I saw a 1/4 inch little creature that looked like an armadillo and curled up into balls when it was touched. I believe this to be an amphipod of some kind. Amphipods are in this size range and posses these characteristics while also being very common in Boston Harbor and around the other organisms that I have previously listed. I did not see it closely enough to determine any kind of sub species.
Finally, I observed what appeared to be a small lobster. It was no more than 1/8th of an inch long and looked exactly like a lobster except it was clear in color and very small. It had the tail and everyrthing. After consulting the guidebook, I believe it to be a mysis larva of lobster.The final thing we were asked to describe was a 2 inch wide sack that was bumpy on the outside and had a clear gel on the inside. It had some algae growing on it and was soft to the touch. I believe this to be a sea grape. Sea grapes are a type of tunicate that are translucent with two little tubes on them. This is consistant with my observations.