>Seas: ca 2-3 feet >Winds 22 knots >Temp 5.6 C ; w/ wind chill –6.3C >Location: Latitude 57 degrees 01.44’ S; Longitude 60 degrees 44.33 W

Above: Soft coral from the Drake Passage. Click on the photo for a larger image.

29 November 2004

We are in the Drake Passage and the seas are light (thank goodness). As we left coastal Argentina and entered the Drake we saw bottom depth abruptly change from ~250 m to >3000 m. The composition of the plankton in this body of water is very different from any we have previously examined – here it is dominated by organisms that spend their life in the plankton (the “holoplankton”). Since sampling the Antarctic Circumpolar Current we have collected 5-6 larvae of barnacles (those crustaceans that cement themselves to a solid object and use the appendages of their midbody (the thorax) to capture particles of food. The larval forms of the two phyla that are the focus of this project, the Annelida (segmented worms) and the Echinodermata (e.g., sea urchins) remain elusive.

Yesterday I wrote about dispersal across the Antarctic Circumpolar Current to and from benthic environments of Antarctica and South America. You might have noted the main current axis runs at right angle to both landmasses. How then could a planktonic larva be transported across this current? Any thoughts? We’ll discuss this “problem” tomorrow.

Our last few samples of the organisms that live on the sea floor, have revealed a tremendous diversity of cnidarians. We have collected soft corals, gorgonians, hard corals and massive hydrocorals. Perched atop these organisms were a large number of brittle stars (Echinodermata: Ophiuroidea). Many of the brittle stars feed on food suspended in the water, and they wave their arms to collect these materials while propped on their cnidarian “host.” The diversity of large invertebrate species in these areas is remarkable.

I’ve been watching the birds that follow our ship again. Lat night I followed more than 100 albatrosses for 10 minutes (1000 bird-minutes) and did not see a single wing flap. It is simply amazing how they maintain position and velocity by ever so slightly changing their wings. Over evolutionary these long-distance fliers have developed a wing designed for soaring and, as a consequence, have minimized the energetic cost of locomotion.