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>Seas: ca 2-3 feet
>Winds 22 knots
>Temp 2 C ; w/ wind chill –15C
>Location: Latitude 59 degrees 24.44’ S; Longitude 59 degrees 59.73 W

Above: A Brown Pteropod — a type of shell-less, "winged" snail that lives in the water column — was the big catch. About an inch in diameter, Its "wings" move in tiny, rhythmic S-curves to propel it through the water as it feeds and mingles with the rest of the column community.

Below: Catch of the Day — A lobate (lobed) ctenophore was captured by the dive group. Scientist Larry Madin says that it has not been described officially for science before, so it remains nameless as an individual species

30 November 2004

Our trip across the Drake Passage, to date, has been uneventful. To be sure, we are aware of the ship movements caused by wind and waves, but the seas have not been nasty (e.g., no coffee cups have been launched). Nevertheless to avoid catastrophe each shower requires three points of contact.

Our regime of sampling the plankton in the upper 200 meters of the water column has been extremely challenging. Collecting the samples is not complicated; however, examining each sample for the presence of invertebrate larvae has been a trying experience. For example, radiolarian protists and diatoms dominated each of the last two tows that I examined. In each tow the density of the unicellular organisms was so high that we couldn’t see through each layer. We then had to dilute our samples in order to examine the entire contents of this vessel. Each 20-minute tow is requiring approximately 12 person-hours to process. In fact, we are unable to completely examine each sample. We preserve the remaining plankton sample and relinquish our microscopes to the next group which arriving with their own samples.

Last night we were able to collect some large "pteropods". The pteropods are a group of heterobranch snails that have adopted a holoplanktonic existence (they remain in the plankton their entire lives). This group is divisible into those species with or without an external shell. Those species with an external shell are the prey items of those species that lack an external shell. Irrespective, the body forms of these two molluskan groups differ from their benthic relatives. The planktonic forms gracefully swim by beating their parapodia (Biol. 219 folks: I know that we’ve learned about a different structure with the same name, but the parapodia of mollusks are derived from the foot.) and can be vividly colored. What adaptations would you expect to find in a snail that remains within the water column? How would you ascertain that these features are actually adaptations?

We are making better time across the Drake Passage than was originally estimated and we will begin sampling of the benthic environment around Elephant Island at 4 a.m. tomorrow. Alas, by beginning at 4 a.m., they will miss the sunrise.

Remember only 25 shopping days before Christmas.

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