Baupläne versus ground patterns, phyla versus monophyla: aspects of patterns and processes in evolutionary developmental biology

The great diversity of their body organization, segmentation patterns, tagmatization, limb types, larval forms, cleavage, and gastrulation modes unmatched by any other arthropod group makes crustaceans desirable and well-suited objects for studies dealing with questions at the interface of evolution and development. In fact, this has a long tradition in biology and even Charles Darwin (1859) took cirripede crustaceans as examples to show interdependencies between ontogeny and evolution. Shortly after Darwin, Fritz Müller (1864) used crustacean larval development to formulate the theory of recapitulation that was popularized by Haeckel (1866) as the biogenetic law ( Scholtz 2000 ; Breidbach 2002 ; Richardson & Keuck 2002 ).