What’s the Difference Between Shrimp and Prawns?

The question usually arises in a kitchen or restaurant: Is there a difference between shrimp and prawns? Are they the same?

In fact, these decapods—crustaceans with ten feet—belong to different suborders and can be further classified by their species. While shrimp and prawns are often confused with one another, their differences are clear if we look closely at their physical characteristics and how they carry their offspring.

Classification

As crustaceans, both shrimp and prawns have "diversified over the course of 455 million years"—long before the great explosion of animal life during the Carboniferous period. Both are also separate members of the order of decopods; most shrimps are pleocyemata, while prawns are dendrobranchiataౠ. Most cold-water shrimps belong in the same suborder as lobsters, crayfish, and crabs.

Characteristics

Prawns and shrimp generally have two- to three-year lifespans. These scavenging omnivores are usually found crawling on the bottom of a body of water. Prawns tend to perch on plants or rocks in calm, warm water, where they prefer to lay their fertilized eggs. Shrimp carry their fertilized eggs on the underside of their bodies until they are born. Both shrimp and prawns have bodies divided into head, thorax, and abdomen; ten walking legs; and thin exoskeletons. In shrimp, the thorax overlaps both the head and the abdomen. This allows the shrimp to curl up into a circle. In prawns, the head overlaps the thorax, while the thorax overlaps the abdomen. Prawns’ bodies are less pliable, so they can’t curl up the way a shrimp can. Along with antennae and a fan tail, shrimp and prawns both have five pairs of legs for swimming and five for crawling around. Their largest set of legs contains pincers. Shrimp have claws on two pair of their legs, and their front set of legs are the largest. Prawns have claws on three pairs of legs, while their second set of legs is the largest. The two decapods also have different types of gills: shrimp have plate-like gills, while prawns have branching gills.

Conservation Status

Roughly 28% of freshwater shrimp species are threatened with extinction, according to Endangered Species International. The International Union for the Conservation of Nature’s Red List of Threatened Species▨ lists seven shrimp and prawn species as extinct, including four in North America. Another 149 are listed as critically endangered, including 33 in North America.

This is especially concerning when we consider the roles these animals play in marine ecosystems. Shrimp and prawns digest organic detritus like leaf litter and cycle their nutrients back into the ecosystem, making them available to plants and phytoplankton. Shrimp and prawns are also key food sources for many wading birds and marine species.

Threats

The threats to shrimp and prawns should come as no surprise: overfishing, habitat destruction, pollution, and climate change.

Overfishing is likely the cause of the 70% decline in shrimp in Kenya’s Malinda-Ungwana Bay between 2000 and 2010. Shrimp constitute roughly 20% (by market value) of the international trade in seafood. The Marine Stewardship Council (MSC), which encourages sustainable fisheries, certifies only 21 fisheries around the world that maintain sustainable stocks of shrimp and prawns.

Habitat destruction has led to the extinction of a shrimp species that once populated the inland wetlands of southern California. Declining water quality, in large part due to pollution and agricultural runoff, has led to low survival rates of shrimp in the deltas of the Mekong and Niger rivers. And increasing water temperatures and decreased marine oxygen levels due to climate change have led to the increasing scarcity of Macrobrachium prawns (an important fishery catch) along the Pacific coast of North and South America.