Penaeus monodon

The giant tiger prawn, known scientifically as *Penaeus monodon*, is a major marine crustacean.

It is widely recognized by several common names, including the Asian tiger shrimp and the black tiger shrimp. This species is extremely important for global food supplies. It is currently the second-most widely cultured prawn species in the entire world. Only the whiteleg shrimp, *Litopenaeus vannamei*, is farmed more extensively. Because of its high demand, *P. monodon* accounts for nearly 50% of all cultured shrimp production.

Physically, these prawns have very distinct markings and sizes. The carapace, which is the hard upper shell, and the abdomen feature alternating red and white transverse bands. Their antennae are a grayish-brown color. The legs, known as pereiopods, and the swimming legs, called pleopods, are brown with red fringing setae. Size differences exist between the sexes. Females can reach lengths of about 33 centimeters and weigh 130 grams. Males are slightly smaller, reaching about 28 centimeters and weighing 90 grams.

These prawns follow a specific life cycle and habitat pattern. Juveniles typically live in shallower areas like mangroves and sandy estuaries. As they reach adulthood, they migrate to deeper waters ranging from 0 to 110 meters deep. They prefer to live on muddy or rocky bottoms. *P. monodon* is also a nocturnal species. This means they are active at night and burrow into the substrate during the day. They emerge at night to feed and to begin mating. During mating periods, a single female can produce approximately 800,000 eggs.

Their diet is quite varied and nutrient-rich. They primarily consume detritus, which is organic matter, along with polychaete worms, mollusks, and small crustaceans. They also eat algae. Interestingly, their feeding appendages prevent them from eating living phytoplankton. However, they are capable of consuming senescent phytoplankton, which refers to aging or dying cells. In aquaculture settings, farmers often provide a compound diet made of dried pellets. Research shows that mixing these pellets with fresh feed improves their reproductive performance.

The history of studying and farming this species is well-documented. Johan Christian Fabricius first described the species in 1798. However, the name was overlooked for a long time. In 1949, Lipke Holthuis clarified the classification. He identified *P. monodon* as the type species for the genus *Penaeus*. In the late 1960s, a man named Liao I-chiu developed new methods for farming these shrimp. His contributions were so significant that he is often called the "Father of Shrimp Farming."

While farming is profitable, it presents many biological challenges. In 2009, global production reached 770,000 tonnes, valued at US$3,650,000,000. Farmers like the quick growth rate and salinity tolerance of *P. monodon*. The species can thrive in various salt levels, though the optimal salinity is 15–25 g/L. However, they are highly vulnerable to viral, bacterial, and fungal infections. Diseases like white spot disease and yellowhead disease cause massive economic losses. In Thailand, the Australian red claw crayfish can even transmit yellowhead disease to these prawns. To solve this, scientists are working to selectively breed lines that are resistant to these pathogens.

Finally, the impact of *P. monodon* extends to ecology and genetics. The species is native to the Indo-Pacific, from Africa to Australia. However, it has become an invasive species in parts of the U.S., specifically from Texas to North Carolina. In 2010, Greenpeace added the species to its seafood red list. They cited concerns regarding the destruction of mangroves, overfishing of juveniles, and human-rights abuses. On a microscopic level, scientists also study their DNA. Research has shown that *P. monodon* uses homologous recombinational repair to fix DNA double-strand breaks. They also use a process called microhomology-mediated end joining to repair their genetic material.