At Sea in the Tropical South Atlantic Ocean
We passed the Tropic of Capricorn yesterday afternoon and have now enjoyed our first full day at sea in the tropics. Conditions today were absolutely delightful with pleasant breezes, warm sunshine, crystal clear blue seas, and scattered white clouds. Obviously, we still have quite a long ways to go before reaching the doldrums of the equatorial belt, because we are now plying waters affected by the southeast trades. We’ve left the large concentrations of petrels and albatrosses behind, and are now in the nutrient-poor area of the South Atlantic Ocean. We really didn’t expect to observe much in the way of wildlife in these parts, so it was exciting to see a totally different type of seabird…that is, a striking white, tropical sea bird with a red beak, aptly named the red-billed tropic bird.
A pod of unidentified dolphins was sighted in the distance in the late morning, but they proved very elusive and we never got close enough to them for identification. However, in the early afternoon, a pod of shortfin pilot whales was spotted and our ship was able to approach them for a much better look. They didn’t seem at all interested in us, so we slowly cruised along with them for a short while and then got back on course. Looking over the bow from the foredeck in hopes of their coming closer to play in the ship’s pressure wave around the bulbous bow showed us just how strikingly clear the water is. With the sun nearly overhead, and very little suspended material in the water column to reflect back sunlight, we could see very far down into the water and observe the beautiful blue aspects of this deep, clear sea.
All day long, National Geographic Explorer sent flying fishes scattering into the air as they made their escape away from what they must have believed was a giant blue and white, surface-feeding, marine predator. Several of us discussed this phenomenon and we’ve decided it is proper to refer to a group of flying fish as a school when they are swimming, but as a squadron when they are flying (Figure A). Let’s hope this new terminology catches on.
Perhaps the most exciting observation of the day was a single flying squid, although most people missed it or assumed the creature was just another flying fish. Flying squid are not nearly as good at gliding as are flying fish, even though they use the same strategy for escaping predators. These animals are seldom seen and very rarely photographed, but Mariano got off one lucky photographic shot that caught enough of the flying squid in the air for undeniable identification (Figure B). In fact, he also thought it was a flying fish and did not realize it was actually a flying squid until he looked at the photograph later. Yes, this is for real and it is not a fake photograph!
