The Malacostraca (`higher crustacea´) are the most speciose crustacean taxon. They are characterized by a unique body plan, but at the same time show a large variety of developmental modes: Direct development (development without larval stages), pseudodirect development or development involving larval stages. Development via a planctotrophic nauplius-larva with three pairs of appendages is commonly viewed as a primitive mode of development. Malacostracan phylogeny suggests that a nauplius-larva evolved independently within the Malacostraca from an ancestor which developed directly or via a more advanced larval stage.
The Malacostraca (`higher crustacea´) are the most speciose crustacean taxon. They are characterized by a unique body plan, but at the same time show a large variety of developmental modes: Direct development (development without larval stages), pseudodirect development or development involving larval stages. Development via a planctotrophic nauplius-larva with three pairs of appendages is commonly viewed as a primitive mode of development. Malacostracan phylogeny suggests that a nauplius-larva evolved independently within the Malacostraca from an ancestor which developed directly or via a more advanced larval stage.
The investigations show, that a primitive embryonic developmental pattern resembling development of a nauplius-larva is more strongly reflected by the development of ectodermal tissues, than by muscle development. Analysis of heterochrony accross the different tissue types shows that secondary evolution of a nauplius-larva within Malacotraca involved only very few heterochronic changes and is largely based on heterochrony in muscle development.