Throughout: Lymph nodes tend to cluster next to blood vessels that feed all the abdominal organs. There are hundreds of lymph nodes within the abdominal cavity, the retroperitoneum (the area by the spine behind the intestines), the pelvis, and the groin. In fact, there all lymph nodes throughout the body (except the brain and eye). ...Read more.
The various fish groups account for more than half of vertebrate species. There are almost 28,000 known extant species, of which almost 27,000 are bony fish, with 970 sharks, rays, and chimeras and about 108 hagfish and lampreys.
Updated May 06, 2016. The International Game Fish Association (IGFA) recognizes eleven species of catfish for records and an additional three kinds of bullhead. Here's some brief information about the most common species found in North American waters.