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The smallest species is the mangrove horseshoe crab (C. rotundicauda) and the largest is the tri-spine horseshoe crab (T. tridentatus). [ 44 ] On average, males of C. rotundicauda are about 30 centimeters (12 inches) long, including a telson that is about 15 cm (6 in), and a carapace about 15 cm (6 in) wide. [ 45 ]
Atlantic horseshoe crab on the shore at Brighton Beach, New York City. The Atlantic horseshoe crab (Limulus polyphemus), also known as the American horseshoe crab, is a species of horseshoe crab, a kind of marine and brackish chelicerate arthropod. [1] It is found in the Gulf of Mexico and along the Atlantic coast of North America. [1]
The horseshoe crab has traditionally been used in investigations into the eye, because it has relatively large ommatidia with large nerve fibres (making them easy to experiment on). It also falls near the base of the chelicerates ; its eyes are believed to represent the ancestral condition because they have changed so little over evolutionary time.
The group has hardly changed in appearance in hundreds of millions of years; the modern horseshoe crabs look almost identical to prehistoric genera and are considered to be living fossils. The most notable difference between ancient and modern forms is that the abdominal segments in present species are fused into a single unit in adults.
Limulus is a genus of horseshoe crab, with one extant species, the Atlantic horseshoe crab (Limulus polyphemus). One fossil species is currently assigned to the genus though several other species have been named, which have since been assigned to other genera. Currently valid species include: [2] Limulus polyphemus (Linnaeus, 1758)
File:Schematic wowza diagram of the human eye.svg International version Based on a bitmap uploaded to the English Wikipedia as Image:Schematic diagram of the human eye.png by User:Delta G . Although it was created in Sodipodi , for some reason it was not uploaded as a vector image.
The horseshoe crabs themselves are also declining in some of their range. They are valuable because of their blue blood, which can be manufactured to detect pathogens in critical medicines such as ...
The following 44 pages use this file: Anterior chamber of eyeball; Aqueous humour; Choroid; Chromostereopsis; Eye; Fovea centralis; Globe (human eye) Human eye; Hyaloid artery; Hyaloid canal; Hyphema; Intraocular hemorrhage; Iris (anatomy) Lens (vertebrate anatomy) Macular telangiectasia; Mammalian eye; Ocular immune system; Optic disc ...