Xiphosura (/ zɪfoʊˈsjʊərə /; [2] from Ancient Greek ξίφος (xíphos) 'sword' and οὐρά (ourá) 'tail', in reference to its sword-like telson) is an order of arthropods related to arachnids. They are more commonly known as horseshoe crabs (a name applied …

2025年3月28日 · horseshoe crab, (order Xiphosura), common name of four species of marine arthropods (class Merostomata, subphylum Chelicerata) found on the east coasts of Asia and of North America. Despite their name, these animals are not crabs at all but are related to scorpions, spiders, and extinct trilobites. Natural history

Xiphosura is an order of marine arthropods that includes horseshoe crabs. It encompasses all existing horseshoe crab species. It is an ancient arthropod that has existed for over 450 million years.

Xiphosurans have existed since the Silurian with relatively little morphological change. The main trends in the evolution of the xiphosurans have been an overall increase in size, a loss of segmentation on the opisthosoma, and a restriction to marine habitats.

Known for their apparent morphological conservatism, for which they have gained notoriety as supposed ‘living fossils’, recent analyses have demonstrated xiphosurans to have an ecologically diverse evolutionary history, with several groups moving into non-marine environments and developing morphologies markedly different from those of the modern...

Xiphosura is an order of marine chelicerates. It includes a large number of extinct lines and only four recent species in the family Limulidae, which include the horseshoe crabs. The group has hardly changed in millions of years.

The Xiphosura are commonly known as horseshoe crabs because the front part of their bodies is horseshoe-shaped. They have sometimes been called king crabs, although this name is also used for a group of large true crabs. Despite their various common names, …

We are talking about Xiphosura, the Horseshoe Crab. The Horseshoe Crab is fascinating! It has hardly changed at all in the past 200 million years and is just about the only Arachnid that lives in the sea.

2023年10月2日 · Xiphosura represents an extant group with a rich fossil record dating back to the Ordovician period. Xiphosurans are often referred to as “living fossils” due to their seemingly unchanged morphology over millions of years.

Xiphosura (; from Ancient Greek ξίφος (xíphos) 'sword', and οὐρά (ourá) 'tail', in reference to its sword-like tail) is an order of arthropods related to arachnids. They are more commonly known as horseshoe crabs (a name applied more specifically to the only extant family, Limulidae).