Hermit crab crab has several long spines, a long, narrow abdomen, and large fringed antennae. Several zoeal moults are followed by the final larval stage, the megalopa. Hermit crabs are often seen as a "throwaway pet" that would live only a few months, but species such as "Coenobita clypeatus" have a 23-year lifespan if properly treated, and some have lived longer than 32 years. Hermit crabs are more closely related to squat lobsters and porcelain crabs than they are to true crabs (Brachyura). However, the relationship of king crabs to the rest of Paguroidea is a highly contentious topic. Many studies based
On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection the connection between natural selection and systems theory. On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection is the title of a joint presentation of two scientific papers to the Linnean Society of London on 1 July 1858: "On The Tendency of Varieties to Depart Indefinitely from the Original Type" by Alfred Russel Wallace and an "Extract from an unpublished Work on Species" from Charles Darwin's "Essay"