mysis

Mysis is a genus of small, shrimp-like crustaceans in the order Mysida, commonly referred to as opossum shrimps. Members of this genus are typically translucent or pale and range in size from a few millimeters to a few centimeters depending on the species. Females carry eggs in a brood pouch formed by the thoracic appendages, a feature that gives rise to the common name opossum shrimp.

Distribution and habitat: Mysis species occur in cold marine and freshwater environments worldwide, from coastal seas to deep lakes. Several freshwater species live in temperate and boreal waters, and some lineages migrate between marine and freshwater habitats during their life cycles.

Ecology and life history: Mysis species generally feed on tiny algae, microzooplankton, and detritus. They are an important prey item for a variety of fishes, birds, and invertebrates, helping to transfer energy from primary production to higher trophic levels. Reproduction is seasonal and species-specific; females brood eggs in the marsupium and release free-swimming larvae that pass through nauplius and mysis stages before reaching maturity.

Significance: In some regions, freshwater Mysis species have become invasive or introduced, altering lake food webs by consuming zooplankton and competing with native species. They are also used as live feed in aquaculture and aquarium contexts, particularly for larval fish due to their high nutritional value.

Taxonomy: The genus includes several species, with notable freshwater representatives such as Mysis relicta and Mysis diluviana.