Fiddler crab two weeks. Fiddler crabs such as "Uca mjoebergi" have been shown to bluff about their fighting ability. Upon regrowing a lost claw, a crab will occasionally regrow a weaker claw that nevertheless intimidates crabs with smaller but stronger claws. This is an example of dishonest signalling. The dual functionality of the major claw of fiddler crabs has presented an evolutionary conundrum in that the claw mechanics best suited for fighting do not match up with the mechanics best suited for a waving display. The internal classification of the genus "Uca" is unstable, but it contains around 100 species arranged among
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Tendency of Varieties to Depart Indefinitely from the Original Type" by Alfred Russel Wallace and an "Extract from an unpublished Work on Species" from Charles Darwin's "Essay"