page_title: Narrow-ridged finless porpoise
section_title: Description
hierarchical_section_title: Narrow-ridged finless porpoise / Description
caption_attribution_description: English: Yangtze finless porpoise in the Institute of Hydrobiology, Chinese Academy of Sciences, on 10 November 2006. 中文（简体）‎: 湖北省武汉市中国科学院水生生物研究所的长江江豚。
context_page_description: The narrow-ridged finless porpoise is a newly accepted species, by the International Union for Conservation of Nature, of porpoise endemic to the western Yangtze river in China and the East China Sea, Yellow Sea, and around Japan. There are two subspecies: the Yangtze finless porpoise and the East Asian finless porpoise. After the functional extinction of the Yangtze river dolphin and the rapid decreasing of population, the Chinese government has given this species the utmost conservation status of National First Grade Key Protected Wild Animal to ensure its survival. Global conservation agencies and charities, such as the World Wildlife Fund and IUCN, have been collaborating with the Chinese government to ensure the survival of the species.
context_section_description: As the name suggests, the finless porpoise is the only porpoise to lack a true dorsal fin. Instead there is a low, narrow ridge covered in thick skin bearing several lines of tiny tubercles. In addition, the forehead is unusually steep compared with those of other porpoises. They have fifteen to twenty-one teeth in each jaw, and, on average, fewer teeth than other porpoises, although there is some overlap, and this is a not a reliable means of distinguishing them.
  Finless porpoises can grow to as much as 2.27 m (7 ft 5 in) in length, and can weigh up to 72 kg (159 lb), although most are smaller. Adults grow more than 1.55 m (5 ft) in length and up to 30–45 kg (65–100 lb) in weight. The flippers are moderately large, reaching up to 20% of the total body length. Adults are typically a uniform, light grey colour, although some may have lighter patches of skin around the mouth, or darker patches in front of the flippers. Newborn calves of the central and eastern subspecies are mostly black with grey around the dorsal ridge area, becoming fully grey after four to six months. However, newborn calves of the western subspecies are a light creamy grey, and become darker as they age.
caption: Narrow-ridged finless porpoises
exif: {"Image ImageWidth": "1547", "Image ImageLength": "2114", "Image BitsPerSample": "[8, 8, 8, 8]", "Image Compression": "LZW", "Image PhotometricInterpretation": "5", "Image Make": "Canon", "Image Model": "Canon EOS-1D Mark II", "Image Orientation": "Horizontal (normal)", "Image SamplesPerPixel": "4", "Image XResolution": "300", "Image YResolution": "300", "Image PlanarConfiguration": "1", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS3 Windows", "Image DateTime": "2011:06:14 10:07:06", "Image ExifOffset": "308", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "1042", "Thumbnail JPEGInterchangeFormatLength": "4575", "EXIF ExposureTime": "1/60", "EXIF FNumber": "14/5", "EXIF ExposureProgram": "Aperture Priority", "EXIF ISOSpeedRatings": "800", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2006:11:10 13:36:13", "EXIF DateTimeDigitized": "2006:11:10 13:36:13", "EXIF ComponentsConfiguration": "YCbCr", "EXIF ShutterSpeedValue": "6", "EXIF ApertureValue": "3", "EXIF ExposureBiasValue": "0", "EXIF MeteringMode": "Pattern", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "17", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "Uncalibrated", "EXIF ExifImageWidth": "1547", "EXIF ExifImageLength": "2114", "EXIF FocalPlaneXResolution": "31750/11", "EXIF FocalPlaneYResolution": "2704000/937", "EXIF FocalPlaneResolutionUnit": "2"}