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>Seas: 6-8 feet
>Temperature: 8C, windchill –6.5C
>Location: 54 degrees 24.11 minutes W; 64 degrees 25.07 minutes S

Above: Thanksgiving dinner aboard the ship.
Below: Preparing for dive operations.

25 November 2004

Happy Thanksgiving

Another productive day aboard the R/V LMG. We awoke to calm seas and the wind speed was less than 5 knots for most of the day. Recently the wind speed has increased to ca. 30 knots and we are beginning to sway a wee bit. The conditions reported on this page reflect current conditions.

Sampling the plankton of the upper 70 m of the water column revealed many different animals – we have clearly entered and are sampling a different water mass. The early morning (6 AM) tow was dominated by zoea larvae of characteristic brachyuran crabs. We also collected several other larval forms for the first time. These include the pilidium larvae of heteronemertean nemerteans, cyphonautes larvae of bryozoans, and echino-and ophioplutei. If Biology 219 does not remember these particular larval forms, they might consult their text. The evening tow was radically different. Pelagic members of chordate subphylum Urochordata, the salps, were the dominant conspicuous invertebrates. Although beyond the scope of our collective project, the presence and abundance of these animals allowed the Kremer-Madin group to begin their studies (see their abstract). Susie Balser and Ken Halanych spent a portion of their “free time” preserving and photographing the cephalochordate (Cephalodiscus sp.) for their collaborative study on this unusual hemichorate worm.

As students of Biology 316 will realize, a detailed examination of a pterobranch hemichordate when compared to the characters expressed by acorn worms (the sister taxon of the Pterobranchia) will hopefully allow for character state polarization and, potentially provide for the assessment the pleisiomorphic characters of the Hemichordata. Why would this be important? Take a moment and devise an answer. Why don’t Susan, Jason, and Dan send me your response by next Tuesday? We will soon be entering an environment that is dominated by extreme environment conditions. Despite this harshness, organisms (plants and animals) are abundant. What might you predict about the significance of seasonal polyphenisms for animal forms that inhabit this environment? Does it matter whether the animal is terrestrial or aquatic?

Cheers to all – I’m on shift for the next four hours.

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