anomurans

Anomura is a diverse infraorder of decapod crustaceans, commonly known as hermit crabs, king crabs, squat lobsters, porcelain crabs, and mole crabs. The name Anomura translates to "uneven tails" in Greek, referring to their often asymmetrical abdomens, which are typically concealed beneath the cephalothorax or within a protective shell. Unlike true crabs (Brachyura), which have a broad, flattened abdomen tucked entirely under the thorax, anomurans have more varied abdominal structures.

This infraorder encompasses a wide range of ecological niches and life forms. Hermit crabs, for instance, are famous for inhabiting discarded mollusk shells, while king crabs are large, commercially important crustaceans found in deep waters. Squat lobsters, despite their name, are not true lobsters but resemble them superficially, often living in crevices and under rocks. Porcelain crabs are small, flattened crabs that filter feed, and mole crabs are burrowing crustaceans found along sandy shorelines.

Anomurans are characterized by having four pairs of walking legs and one pair of chelipeds (claws). The disparity in the development and function of these appendages, particularly the chelipeds, is a common feature. Their reproductive strategies and larval development also vary significantly across the group. Despite their morphological differences, they share common anatomical and evolutionary traits that place them within the infraorder Anomura.