sea90E - an oceanographic expedition to the Indian Ocean



	The Search for the Indo-Pacific Humpback Dolphin By Leslie Nemazi and Rory Wilson (and yes, it is sometimes pink) Although our primary research goal for the 90 East Ridge Expedition is to gather information on the formation of the ridge from a geologic perspective, there are other benefits to our expedition. For example; this region has not been widely traveled, and researchers have only limited data about the whales and other marine mammals. Our marine mammal observers, Laura and Howie, collect information every day about their observations. Additionally, there is a researcher currently reclassifying flying fish, and providing information on Indian Ocean sightings to help with this research. This map shows areas where the Indo-Pacific Humpback Dolphin can be found. See the green areas on the map? One of the areas that we will transit as we go to Singapore is an area that is abundant in marine life, including plankton and fish. It is also a known region where there have been prior sightings of the Indo-Pacific Humpback Dolphin. If we were to see this mammal here or in any other areas, we would certainly report these findings. So let's start by looking at what we might see: No, we did not take this picture. This photo is courtesy of The Princeton Field Guide to Whales and Dolphins. This is an excellent book, by the way, and has great pictures. The small dolphin in front (a calf) is a dark gray and even the mature mammals can be gray, or speckled or pink! Here is the way biologists name dolphins: Common Name: Indo Pacific Humpback Dolphin Latin Name: Sousa Chinensis Other Name: Speckled Dolphin Scientific Classification: Every living thing can be classified scientifically, for identification and scientific purposes. The naming system gives a lot of information about the plant or animal. The names may seem strange because they are in Latin! Here is the scientific classification of the Indo-Pacific Humpback Dolphin: Kingdom Animalia: This means it is an animal. Phylum Chordata: Chordata means that it has a spinal column. Class Mammalia: Indicates that it is a mammal. Order Cetacea, sub-order Odontocete: it is a toothed dolphin, whale or porpoise. Family Delphinidae: Delphinidae means it is an oceanic dolphin. Genus Sousa: Sousa is a type of dolphin with an elongated dorsal fin on a hump. Species Chinensis: This is the specific variety of dolphin. The scientific name is the genus and species of the organism. Here, the dolphins scientific name is Sousa chinensis. So... the scientific naming, or nomenclature system, gives a lot of information about the organism we are interested in. From the name we know that it is an animal, it has a spinal column and that it is a mammal. Even more specifically, it is a toothed oceanic dolphin! There are five varieties of humpback dolphins. The particular species that we are interested in is the Sousa chinensis, commonly called the Indo-Pacific Humpback Dolphin. The Indo-Pacific Humpback dolphin is found along the coasts of the East Indian Ocean and in the SW Pacific, from China to Australia in coastal waters. The RV Revelle is headed that way! The map above shows a broader range. Humpback dolphins in the other areas of the map are a different species. For example, Sousa plumbea is found to the west of India, from South Africa along the coast to Sri Lanka. Its common name is the Indian Humpback Dolphin. The Atlantic Humpback Dolphin is found off western Africa. It is yet another species, and its scientific name is Sousa teuszii. The Indo-Pacific Humpback Dolphin can vary in color from yellow to pink to gray to nearly white. The young dolphins, called calves, are gray and change color as they get older. That is why they are also called the speckled dolphin; because they look speckled in their teenage years as they become pinker! The Indo-Pacific Humpback Dolphin has a long, slender beak similar to the Bottlenose dolphin. They have robust bodies and their underside is lighter in color. The melon, a fatty lump of tissue in the forehead region, is slightly rounded. They are called humpback dolphins because the dorsal fin is elongated, and rests on a 'hump,' on the top of their back. The adults are 2-3m in length and range in weight from 150-280kg. The newborns are generally around 1m in length and weigh around 25kg. Indo-Pacific Humpback Dolphins eat fish, squid and octopus. They are found in shallow tropical and sub-tropical waters of the Indian Ocean. They prefer water with a tidal influence, less than 25m in depth. This means that the inland waterways leading into Singapore are the ideal place to try to see the elusive Indo-Pacific Humpback Dolphin. Wish us luck! Who knows what we will see along the way...
			High.Seas.HIGHTECH/ analyze!ocean@voyages, by lots of us... How to Become a Captain, by the Captain The Search for the Indo-Pacific Humpback Dolphin, by Leslie Nemazi. Rocks Rock! (or ) The Fresh Cut Surface of Beautiful Ocean Rock, by Evelyn Mervine Exploring the Bridge of the RV Roger Revelle Dredging Operations onboard the R/V Revelle, by Amy Eisin Geochemistry of Volcanic Rocks, by Fred Frey Cool Expedition Discoveries Already!, by Will Sager Anatomy of a Seamount Survey, by Will Sager M agnetometers (“Maggie”) and Attracting Sharks, by Rory Wilson Acoustics: Substitute for Superman Vision?, by Will Sager What is Bathymetry?, by Will Sager Hotspots and Ninetyeast Ridge: What’s a hotspot?, by Will Sager