Endoskeleton three phyla and one subclass of animals, endoskeletons of various complexity are found: Chordata, Echinodermata, Porifera, and Coleoidea. An endoskeleton may function purely for support (as in the case of sponges), but often serves as an attachment site for muscle and a mechanism for transmitting muscular forces. A true endoskeleton is derived from mesodermal tissue. Such a skeleton is present in echinoderms and chordates. The poriferan 'skeleton' consists of microscopic calcareous or siliceous spicules or a spongin network. The Coleoidae do not have a true endoskeleton in the evolutionary sense; there, a mollusk exoskeleton evolved into several sorts of internal
Subgroups of Amish Subgroups of Amish Subgroups of Amish developed over the years, as Amish churches have divided many times over doctrinal disputes. The 'Old Order' Amish, a conservative faction that withdrew from fellowship with the wider body of Amish in the 1860s, are those that have most emphasized traditional practices and beliefs. There are many different subgroups of Amish with most belonging, in ascending order of conservatism, to the Beachy Amish, New Order, Old Order, or Swartzentruber Amish groups. Donald B. Kraybill, Karen M. Johnson-Weiner and Steven M. Nolt speak in their book "The Amish" of different Amish "affiliations". They define an