{"id":47921,"date":"2026-07-10T14:38:38","date_gmt":"2026-07-10T18:38:38","guid":{"rendered":"https:\/\/news.maryland.gov\/dnr\/?p=47921"},"modified":"2026-07-15T10:47:09","modified_gmt":"2026-07-15T14:47:09","slug":"native-animal-profile-crayfish","status":"publish","type":"post","link":"https:\/\/news.maryland.gov\/dnr\/2026\/07\/10\/native-animal-profile-crayfish\/","title":{"rendered":"Native Animal Profile: Crayfish"},"content":{"rendered":"
\"Crayfish

A biologist holds up a crayfish found in the Patapsco River. Maryland Department of Natural Resources photo<\/p><\/div>\n

Most of us who have played in shallow water or let our children play in Maryland streams and ponds vividly recall an encounter with a crayfish. It\u2019s usually hiding under a rock, hurriedly scampering along a sandy stream bottom, shooting quickly backwards away from disturbance, or angrily shaking small claws at us as we pluck it out of the water. This creek critter is uniquely charismatic and still quite common despite the increase in threats to its survival. Whether you call it crayfish, crawfish, mudbug, crawdad, freshwater lobster, or another of many common nicknames, this humble crustacean is often seen but not often fully appreciated.\u00a0 <\/span><\/p>\n

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Did you know? The scientific study of crayfish is called Astacology, from the Greek word astak\u00f3s (\u1f00\u03c3\u03c4\u03b1\u03ba\u03cc\u03c2) which means crayfish or lobster, and Astacus – the Latin genus name for European crayfish.<\/em><\/strong><\/p>\n<\/blockquote>\n

Maryland<\/span><\/a> is the proud home to a total of <\/span>14 species of crayfish<\/span><\/a>, nine native species in four genera, and five introduced or invasive species. We\u2019ve got just a small piece of the species distribution pie, with <\/span>more than 640 species<\/span><\/a> total found globally. The southeastern United States boasts a hotspot of global diversity, with <\/span>more than 370<\/span><\/a> species dwelling in our ideal freshwater ecosystems. Crayfish and lobsters don\u2019t just look alike \u2013 they are closely related even though crayfish are found in freshwater and lobsters prefer saltwater. A classroom <\/span>dissection<\/span><\/a> or perusal of a field guide or <\/span>key<\/span><\/a> will demonstrate the many nuances of their complex anatomy. They have ten legs, two of which are claws (called chelipeds, and often lost in battle), strong abdomens for speedy backwards swimming, and feathery gills for breathing underwater. Sometimes you\u2019ll encounter one that\u2019s soft and squishy, having just molted its exoskeleton to allow for growth, get ready for mating, or in response to environmental stimuli. The <\/span>largest crayfish<\/span><\/a> in the world are quite impressive, growing over two feet long, but these hefty specimens do not dwell in our part of the world; our largest species max out at closer to five inches.<\/span><\/p>\n

As a keystone species, crayfish hold an important place in the center of freshwater ecosystems. Like beavers, crayfish are widely considered \u201cecosystem engineers.\u201d They physically modify their environments by foraging, substrate restructuring, and burrowing; three of our Maryland species build characteristic <\/span>\u201cchimneys\u201d<\/span> when they burrow in the mud. These movements and behaviors influence sediment, water, and nutrient flow, creating microhabitats and increasing overall biodiversity. Crayfish serve as omnivorous scavengers and predators, eating just about anything they can grab, other animals\u2019 leftovers, and sometimes even each other! As prey, they feed many hundreds of other species, composing a large part of the diets of countless fish, reptiles, birds and even some mammals. Humans like to eat crayfish too, and we can catch them via various methods here in Maryland with <\/span>a fishing license<\/span><\/a>. The US <\/span>crayfish industry<\/span><\/a> is valued at more than $200 million annually.<\/span><\/p>\n

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A kingfisher snacks on a crayfish. Photo by Scott Moody, submitted to the 2025 DNR Photo Contest.<\/p><\/div>\n

Despite the appearance of abundance in our local streams, crayfish are in fact one of the most vulnerable groups, with a <\/span>high percentage of overall species listed as imperiled<\/span><\/a> or rare. The Endangered Species Act came about in 1973, but it wasn\u2019t until <\/span>the late 1980s<\/span><\/a> that any crayfish were recognized and listed for Federal protection. Right under our noses in streams all over Maryland, many native crayfish are struggling to survive under heavy pressure from invasive species. Unlike most other imperiled animals, local population declines are influenced more by non-native crayfish\u00a0 introductions than habitat loss. These animals have been moved around extensively, introduced all over the world via <\/span>released bait<\/span><\/a> and aquarium pets, as well as some intentional stocking for food or biocontrol purposes. Like other invasive species, they compete with and often introduce disease or hybridize with the native species, causing a severe and rapid decline in biodiversity. Contrary to popular belief, more prey items for fish doesn\u2019t necessarily mean more fish for fishermen. Studies have shown that invasive crayfish can hurt recreational fisheries and create negative economic impacts.<\/span><\/p>\n

Though we may have been the cause of the crayfish\u2019s population decline, we can also be a major contributor to their recovery! Here\u2019s how:<\/span><\/p>\n