Penaeus monodon

Geographic Range:

Giant tiger prawns are native to the coasts of the Arabian Peninsula and the Pacific and Indian Ocean coasts of Australia, Indonesia, south and southeast Asia, and South Africa. They were accidentally introduced to the United States off the coast of South Carolina in 1988, by an unexpected release from an aquaculture centre.

Habitat:

Young giant tiger prawns are most commonly found in estuaries, lagoons and mangroves; they are very tolerant to a range of salinity levels from 2-30 ppt. Adults move into deeper waters and live on rocky or muddy bottoms, ranging in depth from 0-110 m (most commonly at 20-50 m). These shrimps may bury themselves in the substrate during the day, emerging to feed at night. They live in waters ranging from 28-33°C and are unlikely to survive in waters colder than 13°C.

Physical Description:

Giant tiger prawns have a typical prawn body plan including a head, tail, five pairs of swimming legs (pleopods) and five pairs of walking legs (pereopods), as well as numerous head appendages. A carapace (hard exoskeleton) encloses the cephalothorax. Their heads have a rostrum (an extension of the carapace in front of the eyes) and six to eight dorsal teeth, as well as two to four sigmoidally-shaped ventral teeth. A posterior ridge called the adrostral carina extends from the rostrum to the edge of the epigastric spine, which reaches to the posterior end of the carapace. Their first three pairs of pereopods have claws and they are distinguished from other shrimp species by the lack of an exopod (an external branch) on their fifth pleopodia. The telson at the posterior end of the prawn is unarmed, with no spines.

Giant tiger prawns are identified by distinct black and white stripes on their backs and tails; on their abdomens, these stripes alternate black/yellow or blue/yellow. Base body color varies from green, brown, red, grey, or blue. These prawns are very large, reaching 330 mm or greater in length (largest individual found at 336 mm total length) and are sexually dimorphic, with females are larger than males. At sexual maturity, female carapace lengths range from 47-164 mm and their total lengths from 164-190 mm, while male carapace lengths fall between 37 and 71 mm, with total lengths of up to 134 mm. On average, females weigh 200-320 g and males weigh 100-170 g.

Females have a sperm receptacle (thyelycum) located ventrally on the last thoracic segment. After mating, sperm remain in this receptacle until eggs are released. Females have a pair of internal fused ovaries that extend almost the entire length of their bodies, from the cardiac region of the stomach to the anterior portion of the telson. Males have a copulatory organ (petasma, formed by the longitudinally folded endopods of the first pair of pleopods. The presence of an appendix masculina (an oval flap on the second pleopod) can distinguish males from females. Testes are unpigmented/translucent and are found dorsal to the hepatopancreas under the carapace. The vas deferens is also internal, and arises from the posterior margins of the main axis of the testes. Sperm are released through genital pores on the fifth pereopod.