Penaeus monodon Fabricus, J.C. 1798

In their first larval stage, giant tiger prawns feed on their yolk reserves. Later larval stages filter feed on plankton, diatoms, and other small organisms in the water column before becoming benthic feeders with a diet composed of organisms such as polycheate worms (Sabellaridae, Spionidae, Unicidae), as well as detritus. In the wild, adult giant tiger prawns feed on mollusks (including squid, blood clams (Arca sp.) and oysters), small crustaceans (including isopods, crabs and their eggs, and young penaeid prawns, including their own species). In aquaculture, these prawns feed on artificial diets consisting mainly of fishmeal; it has been noted that individuals grow more quickly when fed this diet.

Animal Foods: fish; eggs; carrion ; mollusks; aquatic or marine worms; aquatic crustaceans; other marine invertebrates

Plant Foods: phytoplankton

Other Foods: detritus

Foraging Behavior: filter-feeding

Primary Diet: carnivore (Eats non-insect arthropods, Molluscivore , Vermivore, Scavenger ); omnivore ; planktivore ; detritivore

Throughout their lifetimes, giant tiger prawns face a variety of predators, including birds, comb jellies, crustaceans, and fishes. When adult prawns move from shallow inshore areas to deeper water, their rate of mortality drops.

Giant tiger prawns have developed a variety of defenses to protect themselves from predation. Prawns have spines on either end of their body (a rostrum above the mouth, and a telson located at the dorsal end of the body). Their distinctive stripes and body color, which is similar to their muddy environment, help to camouflage them from predators. These prawns also bury themselves in substrate, not only hiding their bodies but also masking their waste, which would otherwise likely be detected by potential fish predators' chemosensory systems.

Known Predators:

• Black cormorant (Phalacrocorax sulcirostris)
• Green heron (Butoroides striatus)
• Grey heron (Ardea cinerea)
• Purple heron (Ardea purpurea)
• Cuttlefish (Sepia officinalis)
• Squid (Order Teuthida, Class Cephalopoda)
• Barramundi (Lates calcarifer)
• Red Snapper (Lurjanus argenrimaculatus)
• Sea basses (Serranidae sp.)
• Cartilaginous fishes (Class Chondrichthyes)
• Mantis Shrimp Oratosquilla oratoria
• Blue swimmer crab (Portunus pelagicus)
• Mud crab (Scylla serrata)

Anti-predator Adaptations: cryptic

Eggs begin development by slowly sinking to the bottom of outer littoral areas. Giant tiger prawns develop through a complex life cycle beginning with three larval stages. Naupilii hatch twelve to fifteen hours after spawning is completed and look like tiny spiders. Larvae at this stage do not feed, instead surviving on their yolks as they are carried by tidal currents from open ocean towards shore. Naupilii larvae pass through six quick molts, increasing their body size. Individuals in the next larval stage, called protozoea, are identified by increased body size and length, the appearance of feathery appendages and, though still planktonic, beginning to feed. After molting three more times, protozoea proceed into the mysis larval stage. At this stage, they begin to have characteristics of adult prawns including segmented bodies, eye stalks, and tails. Mysis larvae molt three more times, becoming postlarvae. At this point in the life cycle, they change from planktonic to benthic feeding. This entire process takes two to three weeks. Prawns continue to molt through a juvenile phase, lasting 1-6 months. Juveniles and adults are distinguished mainly by location and carapace length. Carapace lengths of juveniles range from 2.2-11 mm and they are found mainly in estuarine areas located at the mouth or middle of bays and mangroves while adults are found in outer littoral areas of full salinity, and have carapace lengths ranging from 37-81 mm.

Development - Life Cycle: metamorphosis

Giant tiger prawns are known to mate prior to ovarian maturation; females store sperm in sacs within their closed thelycum until eggs are fully mature. Although little is known regarding specific mating behaviors, it has been noted that this species mates nocturnally, in off-shore waters, shortly after females have molted and their carapaces are still soft (males typically still have hard carapaces during breeding). Copulation begins with a male swimming parallel to a female. The male bends his body and first pair of pleopods with the petasma (caught by the appendix masculina) stretched vertically down, in order to facilitate the forward swinging of the second pair of pleopods. The first pair of pleopods pulls apart the petasmal halves, preventing the loss of sperm during copulation. The pair then takes an abdomen-to-abdomen position. The female exerts pressure on the male's petasma using her 4th pair of pereiopods and a spermatophore (sac of sperm) is thrust into her thyelycum, after which the pair separate. A majority of adult individuals copulate more than once; females are known to spawn 4 times during their lives, at carapace lengths of 50, 62, 66, and 72 mm.

Mating System: polygynandrous (promiscuous)

It is difficult to estimate age at sexual maturity, but males become mature upon reaching an average carapace size of 37 mm, females at 47 mm. Females can produce 248,000-810,000 eggs at a time and are known to spawn up to four times during their lifespan. Once eggs are mature, they are expelled in a greenish-white cloud, along with stored spermatophores, into the ocean where external fertilization occurs. Eggs range in size from 0.27-0.31 mm.

Breeding interval: Females spawn 4 times during their lifespan at carapace lengths of 50, 62, 66, and 72 mm. It is unknown how many times males mate.

Breeding season: This species breeds year round.

Range number of offspring: 248,000 to 810,000.

Range gestation period: 12 to 15 hours.

Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); broadcast (group) spawning; oviparous ; sperm-storing ; delayed fertilization

Males exhibit no parental involvement after mating. Females invest by yolking and protecting eggs while they are still in their bodies. They exhibit no further parental involvement once eggs and sperm have been released.

Parental Investment: female parental care ; pre-fertilization (Provisioning, Protecting: Female)