Agnathans - Encyclopedia.com
2018年5月29日 · However, many extinct agnathans had extensively developed bony plates directly under the skin. These were most often found in the region of the skull and served as a protective armor. Bony plates are not present in extant agnathan species. Major Groups of Living Agnathans. There are two major groups of living agnathans, the lampreys and the hag ...
Gnathostomata - Encyclopedia.com
2018年5月23日 · Gnathostomata. 1. A superclass of jawed vertebrates that includes the fishes, Amphibia, Reptilia, Aves, and Mammalia. Recently it has been proposed that Gnathostomata should comprise the Elasmobranchii (sharks, rays, etc.) and the Teleostomi (i.e. Osteichthyes and Sarcopterygii). In this classification Pisces becomes redundant.
Lampreys and Hagfishes - Encyclopedia.com
Resources. Lampreys and hagfishes are unusual, jawless fish that comprise the orders Myxiniformes (hagfishes) and Petromysoniformes (lampreys). There are approximately 40 species of lampreys and approximately 35 species of hagfishes and slime hags. Lampreys and hagfishes lack the scales typical of most fish, and are covered with a slimy mucous.
Zoology: Invertebrates Category - Encyclopedia.com
Find facts and information about Zoology: Invertebrates from trusted sources at Encyclopedia.com
Human and Primate Evolution - Encyclopedia.com
Humans are primates, related to apes, monkeys, and lemurs, and many of the unique characteristics of the species are a result of the social and ecological interactions of our ancient primate ancestors. Human evolution built upon general primate adaptations by elaborating several major innovations, such as upright walking, tool use, culture, and ...
Coelacanths and Lungfishes: Sarcopterygii | Encyclopedia.com
Instead ofbeing made up of individual bones, or vertebrae (ver-teh-BREE), the backbone is a stiff tube. Coelacanths are bluish gray with white mark-ings. They weigh 110–198 pounds (50–90 kilograms). Female coela-canths can be as long as 6 feet (1.9 meters) and males as long as 5 feet (1.50 meters). Geographic range: Coelacanths live on both ...
Fish (Saltwater) - Encyclopedia.com
Fish usually live surrounded entirely by water. They all have gills for breathing and fins for swimming. Most fish are ectotherms, which means that their bodies are nearly the same temperature as the water in which they live. About 60% of all fish live entirely in saltwater, while the rest live in freshwater or both freshwater and saltwater.