Shrimp

Shrimp are widespread and abundant crustaceans with elongated bodies. They are primarily defined by their swimming mode of locomotion. Most shrimp belong to the decapod order, specifically the Caridea or Dendrobranchiata groups.

While some researchers use narrower definitions, shrimp are generally understood as stalk-eyed swimming creatures. They possess long, narrow muscular tails known as abdomens. They also have long whiskers called antennae and slender, biramous legs. These animals are vital components of global ecosystems. They serve as a major food source for many larger animals, including fish and whales.

A shrimp's body structure is highly specialized for life in the water. The head and thorax are fused into a single section called the cephalothorax. A thick, hard shell called the carapace protects this cephalothorax and covers the gills.

At the front, a rigid extension called the rostrum acts like a beak. This rostrum can be used for defense or for attacking. The shrimp's eyes are compound eyes located on stalks. These eyes provide panoramic vision, which is excellent for detecting movement.

Two pairs of antennae emerge from the head. The long antennae help the shrimp orient itself in its surroundings. The shorter antennae contain sensors used to "smell" or "taste" chemicals in the water.

Movement is a key way to distinguish shrimp from other crustaceans. To swim forward, shrimp paddle swimmerets, or pleopods, located on their abdomen.

However, they have a unique escape response called lobstering. During this reaction, the shrimp performs repeated flicks of the tail. This action drives the animal backward very quickly to avoid predators. This differs significantly from crabs and lobsters. While those animals have strong legs for walking, shrimp have thin, fragile legs. Shrimp use these slender legs primarily for perching rather than walking.

There is significant linguistic confusion regarding the terms "shrimp" and "prawn." These are common names rather than formal scientific taxa. Because they are colloquial terms, they lack definite scientific definitions.

Taxonomist Tin-Yam Chan notes that usage is often confused or even reversed between different regions. Historically, the distinction often related to size or location. In the United States, larger commercially fished species are often called shrimp. In other English-speaking countries, these same large species are frequently called prawns. The term "shrimp" itself dates back to the 14th century. It is related to Middle English and Old Norse words meaning to contract, wrinkle, or shrivel.

Scientific classification has helped organize our understanding of these creatures. In 1758, Carl Linnaeus categorized the common shrimp, *Crangon crangon*. Later, in 1777, Thomas Pennant categorized the common prawn, *Palaemon serratus*.

These two species helped shape European taxonomic studies. The common shrimp is a small, burrowing species. In contrast, the common prawn is much larger. While biologists sometimes try to limit these names to specific groups, popular usage remains flexible. Today, the terms shrimp and prawn are often used almost interchangeably in common speech.

Shrimp are also a massive part of the global economy. Humans widely catch and farm shrimp for food, specifically eating the muscular tails.

This is a massive industry worth 50 billion dollars every year. In 2010, total commercial production reached nearly 7 million tonnes. Shrimp farming became very prevalent during the 1980s, especially in China. By 2007, the harvest from shrimp farms actually exceeded the capture of wild shrimp.

This shift has brought concerns regarding excessive bycatch and overfishing. Additionally, waterways used for farming can suffer from pollution.

Understanding shrimp requires comparing them to other decapods like crabs and lobsters. Lobsters and crabs are adapted for walking on the seafloor.

Crabs have wide, flat carapaces and short antennae. They also have prominent grasping claws and move sideways. Shrimp, however, have cylindrical carapaces and long antennae. Even lobsters, which can "lobster" with their tails to escape, primarily use walking legs. This distinction between swimming and walking was once the primary way to divide these animals into different suborders. Shrimp belong to the group adapted for swimming, while crabs belong to the group adapted for crawling.