Monday, August 2, 2010

The Barking Crab- continued!

Sea creature #4 is one of two organisms I saw today that I have tasted. It had two symmetrical shells joined by a hinge on the curved side and stuck together, presumably by a substance produced by the organism within, on the other side. One end of the shells came to a point, and the other was more rounded. The outer surfaces of the shells were black with brownish striations along the length and slightly raised ribs following the curve of the shell. Some of the creatures were dead, and the insides of the open, empty shells were shiny and light-colored.
Hypothesis: Blue Mussel (Mytilus edulis).

The Orange Thing: Prof. Berman found a rock with an interesting growth that looked like orange flowers with 8-12 petals. They were bright orange.
Hypothesis: The closest thing I could find in the Audubon guide that exists on our coast is the golden star tunicate (Botryllus schlosseri); however, the petal-like sections were not outlined in yellow or white. The organism was more similar to the Pacific star tunicate (Botryllus tuberatus).

Sea plant #1 is the second of two organisms I saw today that I have tasted. I don’t recall what it tasted like, but I know I ate some of this stuff when I was little and considered the dollar bill my brother offered me a fortune. We first observed the plant in the intertidal zone at Long Wharf, and again attached to the floats at the Barking Crab. The end attached to the float was flat and dark olive green. It branched several times and terminated in lighter green, air (or some sort of gas) filled sacs or pods. The surfaces of the pods and what I’ll call leaves or branches were covered with raised bumps.
Hypothesis: Rockweed (Fucus vesiculosis).

Sea plant #2 consisted of flat, broad membrane-like leaves. It was bright green and surprisingly transparent. It looked a lot like an aquatic version of lettuce, but the leaves were slick. The specimen I observed was about six inches long and two and a half inches wide. It was more resistant to tearing than I expected, given how thin it was.
Hypothesis: Sea lettuce (Ulva lactuca). According to Encyclopedia Brittanica (the online version), sea lettuce is two cells thick and embedded in a tough gelatinous sheath, which explains the transparency, the slickness and the toughness of the seaweed. I also observed a red seaweed very similar to it but more slimy. At first I thought it was a variation of the same species, but after reading the Hitchhikers Guide I think it is red alga (Grateloupia turuturu).

Sea plant #3 was found both in the intertidal zone at Long Wharf (both on the rocks of the wall and in the water) and attached to the floats at the Barking crab. Like Sea plant #2, it was bright green, but the similarities end there. This plant consisted of many very fine strands several inches long.
Hypothesis: Blidingia minima (couldn’t find a common name). According the NPS, B. minima is found in the high intertidal zone on the shoreline and most of the islands of Boston Harbor.

Hypothesis regarding the seawall behind the IMAX: If the surrounding tall buildings were removed, rockweed and Blidingia minima would gradually become more prevalent and the species composition on the rock wall would eventually resemble that of the wall at Long Wharf. In the shade, the barnacles we saw behind the IMAX out-compete the relatively shade-intolerant seaweeds for space. However, if sun exposure increased, the seaweeds would probably quickly colonize gaps left by barnacles.

Hypotheses regarding seaweed order on the wall at Long Wharf: The top layer of the wall was bare rock (probably too little time in the water for seaweed and barnacles to survive, since this would only be submerged at the highest tides); the second layer was mostly Blidingia minima (with enough time in the water to survive dry periods at low tide, and shallow enough to get enough sun to require/support production of that much chlorophyll), then a mix of rockweed (which can probably survive with less sunlight than B. minima) and barnacles (since I saw behind the IMAX that these can survive at depths as shallow as those at which B. minima was dominant at Long Wharf, I’m guessing these were just outcompeted by B. minima in the shallower zone but not by rockweed in the deeper intertidal zone).

My pictures and drawings will be attached with my post on Lovell's island- technical issues!

Alissa Frame

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