There is a great deal of confusion about this term because it's used to describe several different shellfish. 1. The first definition refers to a species that's part of the lobster family and includes those variously called Dublin Bay prawn, Danish lobster, Italian scampi, langoustine (French), langostino (Spanish), Caribbean lobsterette and Florida lobsterette. These "prawns" have bodies shaped like tiny Maine lobsters including minuscule claws. The meat has a sweet, delicate flavor that some claim is better than either lobster or shrimp. These "prawns" are 6 to 8 inches in length and have pale-red bodies deepening to dark-red tails. 2. A second definition applies to the freshwater prawn (identified by the Latin name Macrobrachium); the term distinguishes shrimp as living in salt water and prawns as freshwater creatures. In truth, these prawns migrate (much like salmon) from salt water to fresh water to spawn. They look like a cross between a shrimp and a lobster, with their bodies having narrower abdomens and longer legs than shrimp. See also hawaiian blue prawn. 3. The term "prawn" is also loosely used to describe any large shrimp, especially those that come 15 (or fewer) to the pound (also called "jumbo shrimp").
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.