Kuruma Prawn

Males of M. japonicus can reach a total length of 17 cm (6.7 in), while females may reach 27 cm (11 in) and a mass of 130 grams (4.6 oz), making it one of the largest species in the family Penaeidae. The body is pale, with brown bands across the back, while the pereiopods and pleopods (walking and swimming legs, respectively) are pale yellow near their bases, and blue near the tips. The rostrum bears 8–10 spines on the top, and one or two below.

The natural distribution of M. japonicus extends from the coast of East Africa and the Red Sea as far east as Fiji and Japan. M. japonicus has entered the Mediterranean Sea as a Lessepsian migrant, through the Suez Canal. It was first observed in Egypt in 1924, and has since spread through the Levant and around the coast of Turkey. Further populations have been established after the species was released at various sites around France, Italy, and Greece.

M. japonicus lives in bays and inland seas, particularly where warm currents occur. It is nocturnal, remaining buried in the substrate during the day. Its predators include bony fishes and cartilaginous fishes. When the sea temperature exceeds 20 °C (68 °F), spawning can begin. During copulation, the male transfers a spermatophore to the female, which she stores in a seminal receptacle. She travels to deep water, where she then releases around 700,000 eggs. These hatch as nauplii, and pass through further five nauplius stages, three zoeae, and three mysis stages by moulting before reaching the postlarval stage.