Systematics and Evolution of Decapod Crustaceans

Decapod crustaceans, comprising prawns, shrimps, lobsters, crabs and allied groups, represent one of the most diverse and ecologically pivotal lineages within Arthropoda. Modern classification recognises several infraorders—Dendrobranchiata, Stenopodidea, Caridea, Astacidea, Achelata, Anomura and Brachyura—each exhibiting distinct morphological and developmental traits. The fossil record, extending from the Late Palaeozoic, reveals successive radiations during the Mesozoic and Cenozoic, driven by shifts in larval ecology, morphological innovation of the carapace and chelae and the colonisation of new ecological niches. Molecular phylogenies have refined relationships among major clades, resolving deep splits and uncovering convergent trends, such as repeated gigantism in body size and multiple independent invasions of freshwater and terrestrial environments. Studies of larval forms, including specialised zoeal and megalopal stages, have shed light on biogeographical dispersal and lineage diversification. Integration of morphological, molecular and stratigraphic data continues to reshape decapod systematics, emphasising the interplay between form, function and environment in this globally significant group that underpins major fisheries, benthic ecosystem processes and evolutionary research.

Research from Nature Portfolio

New evidence of early parasite–host interactions indicates that epicaridean isopods infested marine shrimps at least 110 million years ago, suggesting the Tethys Sea as a dispersal corridor for these crustacean parasites. A landmark discovery of a complete 150-million-year-old crab larva reveals modern-like zoeal and megalopal morphology long before the Cretaceous, extending our understanding of early brachyuran development and raising fresh questions about ancestral life cycles. Unusually large crab claws from Upper Cretaceous continental deposits demonstrate the presence of portunoid crabs in freshwater settings, pushing back the freshwater colonisation of true crabs by some 40 million years and illustrating multiple independent invasions of non-marine habitats.

Systematics and Evolution of Decapod Crustaceans publication trend

The graph below shows the total number of articles in systematics and evolution of decapod crustaceans across all publications each year (not limited to Nature Index journals).

Technical terms

Infraorder: A taxonomic rank below order, grouping closely related families.

Brachyura: “True crabs” characterised by a shortened abdomen folded under the thorax.

Epicaridean isopods: Obligate parasitic isopods that live on or in decapod hosts.

Zoëa and Megalopa: Distinct larval stages in brachyuran development before juvenile form.

Phylogeny: The evolutionary history and relationships among taxa.

Morphospace: A multidimensional representation of morphological variation.

References

1. 110-million-years-old fossil suggests early parasitism in shrimps. Scientific Reports (2023).
2. A 150-million-year-old crab larva and its implications for the early rise of brachyuran crabs. Nature Communications (2015).
3. The oldest freshwater crabs: claws on dinosaur bones. Scientific Reports (2019).
4. New Cretaceous crabs (Crustacea, Brachyura) from Moscow Oblast and Dagestan (Russia): patterns in phylogeny and morphospace of the oldest eubrachyurans (Dorippoidea). Cretaceous Research (2021).
5. Origin, early evolution and palaeoecology of Gymnopleura (Crustacea, Decapoda): Basal palaeocorystoid crabs from the Upper Jurassic–Lower Cretaceous of central Europe. Palaeogeography Palaeoclimatology Palaeoecology (2021).