Ecuadorian hermit crab Ecuadorian hermit crab The Ecuadorian hermit crab (Coenobita compressus) also known as the Pacific hermit crab is a species of land hermit crab. It is one of the two land hermit crabs commonly sold in North America as a pet, the other being the Caribbean hermit crab ("Coenobita clypeatus"). "Coenobita compressus" is a member of the phylum Arthropoda and the class Malacostraca. They can be up to in length and are thought to be one of the smallest species of land hermit crabs. They have four walking legs, a small pincer, a large pincer, and antennae. Many people who keep
History of manifolds and varieties History of manifolds and varieties The study of manifolds combines many important areas of mathematics: it generalizes concepts such as curves and surfaces as well as ideas from linear algebra and topology. Certain special classes of manifolds also have additional algebraic structure; they may behave like groups, for instance. In that case, they are called Lie Groups. Alternatively, they may be described by polynomial equations, in which case they are called algebraic varieties, and if they additionally carry a group structure, they are called algebraic groups. The term "manifold" comes from German "Mannigfaltigkeit," by Riemann. In English, "manifold" refers to