[5] In Northern America, P. macrodactylus can also be found in the US states of Washington,[6] Oregon,[7] Virginia,[8] Connecticut,[9] and New York.

[8] It is thought that its introduction was accidental via discharge of ballast water from the US to Mar De Plata harbor in Argentina.

Palaemon macrodactylus naturally tolerates moderate salinity levels, inhabiting brackish water.

Environmental temperature directly influences the reproducing rate of female individuals, as well as the timing and duration of breeding season (optimal between 15 and 27 °C (59 and 81 °F)).

In particular, local shipping to suitable regions that have not been inhabited with any of the species community effectively introduces P. macrodactylus to new habitats marked by preferential temperature regimes.

Nevertheless, it is actually a threatened species listed in the China Red Data Book, despite having a broad native range with high reproductive potential.

[18] Females tend to be larger than males and are pigmented with red spots on the body surface with white longitudinal stripes going down the back.

[19] Palaemon macrodactylus typically eats plants, mysids such as Neomysis mercedis, amphipods, and crabs.

[24] In shrimps, a courting ritual is common and mating consists of indirect sperm transfer which is through olfactory and tactile cues.

[8] According to a study by Richard Sitts and Allen Knight published in 1979, P. macrodactylus is mainly carnivorous because animal fragments are commonly found to be excessive compared to plant materials in their foreguts.

According to a study in Sacramento-San Joaquin River Delta, California, P. macrodactylus and C. franciscorum both prey on Neomysis mercedis, an opossum shrimp.