Crayfish are freshwater crustaceans resembling small lobsters (to which they are related). In some locations, they are also known as crawfish, craydids, crawdaddies, crawdads, freshwater lobsters, mountain lobsters, rock lobsters, mudbugs, or yabbies. Taxonomically, they are members of the superfamilies Astacoidea and Parastacoidea. They breathe through feather-like gills. Some species are found in brooks and streams, where fresh water is running, while others thrive in swamps, ditches, and paddy fields. Most crayfish cannot tolerate polluted water, although some species, such as Procambarus clarkii, are hardier. Crayfish feed on animals and plants, either living or decomposing, and detritus.
Most crayfish cannot tolerate polluted water , although some species, such as Procambarus clarkii , are hardier. In the Eastern United States , “crayfish” is more common in the north, while “crawdad” is heard more in central and southwestern regions, and “crawfish” farther south, although considerable overlaps exist.
A further genus of astacid crayfish is found in the Pacific Northwest and the headwaters of some rivers east of the Continental Divide . Many crayfish are also found in lowland areas where the water is abundant in calcium , and oxygen rises from underground springs. In 1983, Louisiana designated the crayfish, or crawfish as they are commonly called, as its official state crustacean.
 Crawfish are a part of Cajun culture dating back hundreds of years.  A variety of cottage industries have developed as a result of commercialized crawfish iconology. In England and Ireland, the terms crayfish or crawfish commonly refer to the European spiny lobster , a saltwater species found in much of the East Atlantic and Mediterranean.
In Europe, they are particularly threatened by crayfish plague, which is caused by the North American water mold Aphanomyces astaci. This water mold was transmitted to Europe when North American species of crayfish were introduced.  Species of the genus Astacus are particularly susceptible to infection, allowing the plague-coevolved signal crayfish (native to western North America) to invade parts of Europe .
In most prepared dishes, such as soups, bisques and touffes , only the tail portion is served. At crawfish boils or other meals where the entire body of the crayfish is presented, other portions, such as the claw meat, may be eaten. Global crayfish production is centered in Asia, primarily China.
Prior to the 1960s, crayfish was largely inaccessible to the urban population in Sweden and consumption was largely limited to the upper classes or farmers holding fishing rights in fresh water lakes. Crayfish are preyed upon by a variety of ray-finned fishes ,  and are commonly used as bait , either live or with only the tail meat. When using live crayfish as bait, anglers prefer to hook them between the eyes, piercing through their hard, pointed beak which causes them no harm; therefore, they remain more active.
An Illinois State University report that focused on studies conducted on the Fox River and Des Plaines River watershed stated that rusty crayfish , initially caught as bait in a different environment, were dumped into the water and “outcompeted the native clearwater crayfish“.  Other studies confirmed that transporting crayfish to different environments has led to various ecological problems, including the elimination of native species. A report by the National Park Service  as well as video and anecdotal reports by aquarium owners  indicate that crayfish will eat their molted exoskeleton “to recover the calcium and phosphates contained in it.”
 As omnivores, crayfish will eat almost anything; therefore, they may explore the edibility of aquarium plants in a fish tank. However, most species of dwarf crayfish, such as Cambarellus patzcuarensis , will not destructively dig or eat live aquarium plants. The three species commonly imported to Europe from the Americas are Orconectes limosus , Pacifastacus leniusculus and Procambarus clarkii .
There is a potential for ecological damage when crayfish are introduced into non-native bodies of water: e.g., crayfish plague in Europe, or the introduction of the common yabby ( Cherax destructor ) into drainages east of the Great Dividing Range in Australia. The Protivin brewery in the Czech Republic uses crayfish outfitted with sensors to detect any changes in their bodies or pulse activity in order to monitor the purity of the water used in their product. The creatures are kept in a fish tank that is fed with the same local natural source water used in their brewing.
Scientists also monitor crayfish in the wild in natural bodies of water to study the levels of pollutants there. ^ Christoph Needon; Johannes Petermann; Peter Scheffel; Bernd Scheibe (1971). “An updated classification of the freshwater crayfishes (Decapoda: Astacidea) of the world, with a complete species list” .
“Feral populations of the Australian Red-Claw crayfish ( Cherax quadricarinatus von Martens ) in water supply catchments of Singapore” . ^ “White-clawed (or Atlantic stream) crayfish (Austropotamobius pallipes) – Special Areas of Conservation” . “Phylogeny of fossil and extant freshwater crayfish and some closely related nephropid lobsters”.
Evolution of Crustaceans at the edge of the end-Permian crisis: ichnonetwork analysis of the fluvial succession of Nurra (Permian-Triassic, Sardinia, Italy). “Oldest Australian crayfish fossils provide missing evolutionary link” . ^ Paul A. Selden; Alison N. Olcott; Matt R. Downen; Dong Ren; Chungkun Shih; Xiaodong Cheng (2019).
“The supposed giant spider Mongolarachne chaoyangensis , from the Cretaceous Yixian Formation of China, is a crayfish” (PDF) . ^ Lunda, Roman; Roy, Koushik; Dvorak, Petr; Kouba, Antonin; Mraz, Jan (2020). “Kids’ Inquiry of Diverse Species, Orconectes propinquus, northern clearwater crayfish: INFORMATION” .
^ J. Thompson; F. Parchaso; A. Alpine; J. Cloern; B. Cole; O. Mace; J. Edmunds; J. Baylosis; S. Luoma; F. Nichols (13 December 2007). “Translocation of the Yabby Cherax destructor into eastern drainages of New South Wales, Australia” .
What is the habitat of a crayfish?
Species of crayfish are widely distributed throughout the world and are found abundantly in most of the continental United States. They live in ponds, streams, rivers, and lakes most typically under submerged rocks and logs.
Where do crawfish live naturally?
Crawfish are freshwater crustaceans that resemble miniature lobsters, ranging in size from 3 1/2 to 7 inches. Over 400 species are found worldwide, 250 of which are in North America, living in rivers, lakes, swamps, canals, wetlands and irrigation ditches.
Where do crayfish live in lakes?
DESCRIPTION: Rusty crayfish live in lakes, ponds and streams, preferring areas with rocks, logs and other debris in water bodies with clay, silt, sand or rocky bottoms.
What ocean do crayfish live in?
Habitat and Diet. Besides size, the major difference between lobsters and crayfish is that lobsters live in saltwater, such as oceans and seas, while crayfish live in freshwater, including lakes, rivers, streams and ponds.
Crayfishes are freshwater decapod crustaceans that live in a variety of aquatic habitats worldwide. They are related to better known decapods such as lobsters, crabs, and shrimp. Crayfishes are native to all continents except Africa and Antarctica and are most common in North America. Of the approximately 625 species found on earth, over 400 live in North America, with the southeastern United States being the center of global diversity. We see this same pattern of biodiversity with other temperate aquatic organisms such as freshwater fishes and mussels. The other area with a major crayfish fauna is Australia with over 150 species.
Crayfishes can be found in a variety of habitats including streams, lakes, marshes, roadside ditches, cave systems, and even in burrows that are sometimes well away from open water. In Georgia, primary burrowing species are typically found in low, wet (swampy) areas, often in the floodplains of streams or rivers.
Thus, they are converting plant energy into protein in the form of a large tail muscle and thereby become an important food source for a host of organisms. In juvenile and Form II males, the gonopod appears to be the same color and consistency throughout its length and has more blunt and rounded features. Individuals of the western North American genus Pacifasticus reach sizes of 78 inches while the Tasmanian lobsters ( Astacopsis spp.)
An unforeseen event such as a chemical spill would sharply reduce the total numbers of a given species and increase the probability of local population loss (extirpation) or in some cases global extinction. If a species is introduced to a new river system, it has the potential to take over the new area if it has traits such as faster and larger growth, the ability to produce more young, or by being more aggressive.
Crayfish are freshwater crustaceans that are used for many purposes, which includes keeping them as pets. This article provides information on crayfish habitat, and some interesting facts about crayfish as well.
Crayfish mostly rest underneath rocks, among submerged logs and twigs, and remain hidden among other aquatic vegetation such as weeds or grass. When in their natural habitat, crayfish mostly feed on decomposing animal matter or decayed leaves as these are easy for them to rip off with their claws.
The term “crayfish” is applied to saltwater species in some countries.
The name “crayfish” comes from the Old French wordSome kinds of crayfish are known locally as lobsters,The study of crayfish is called astacology.
Fossil records of crayfish older than 30 million years are rare, but fossilised burrows have been found from strata as old as the late Palaeozoic or early Mesozoic.
Threats to crayfish
Crayfish are susceptible to infections such as crayfish plague and to environmental stressors including acidification. In Europe, they are particularly threatened by crayfish plague, which is caused by the North American water moldAcid rain can cause problems for crayfish across the world. In whole-ecosystem experiments simulating acid rain at the Experimental Lakes Area in Ontario, Canada, crayfish populations crashed – probably because their exoskeletons are weaker in acidified environments.
In several countries, particularly in Europe, native species of crayfish are under threat by imported variants, particularly the signal crayfish (
Crayfish are eaten worldwide. Like other edible crustaceans, only a small portion of the body of a crayfish is eaten. In most prepared dishes, such as soups, bisques and étouffées, only the tail portion is served. At crawfish boils or other meals where the entire body of the crayfish is presented, other portions, such as the claw meat, may be eaten.Global crayfish production is centered in Asia, primarily China. In 2018, Asian production accounted for 95% of the world’s crawfish supply.Crayfish is part of Swedish cuisine and is usually eaten in august at special Crayfish parties (SwedishIn the United States, crayfish production is strongly centered in Louisiana, with 93% of crayfish farms located in the state as of 2018.Like all crustaceans, crayfish are not kosher because they are aquatic animals that do not have both fins and scales.
Crayfish are preyed upon by a variety of ray-finned fishes,When using crayfish as bait, it is important to fish in the same environment where they were caught. An Illinois State University report that focused on studies conducted on the Fox River and Des Plaines River watershed stated that rusty crayfish, initially caught as bait in a different environment, were dumped into the water and “outcompeted the native clearwater crayfish“.
Crayfish are kept as pets in freshwater aquariums. They prefer foods like shrimp pellets or various vegetables, but will also eat tropical fish food, regular fish food, algae wafers, and small fish that can be captured with their claws. A report by the National Park ServiceIn some nations, such as the United Kingdom, United States, Australia, and New Zealand, imported alien crayfish are a danger to local rivers. The three species commonly imported to Europe from the Americas are
The Protivin brewery in the Czech Republic uses crayfish outfitted with sensors to detect any changes in their bodies or pulse activity in order to monitor the purity of the water used in their product. The creatures are kept in a fish tank that is fed with the same local natural source water used in their brewing. If three or more of the crayfish have changes to their pulses, employees know there is a change in the water and examine the parameters.Scientists also monitor crayfish in the wild in natural bodies of water to study the levels of pollutants there.
Introduction to the Crayfishes of Georgia
Crayfishes are freshwater decapod crustaceans that live in a variety of aquatic habitats worldwide. They are related to better known decapods such as lobsters, crabs, and shrimp. Crayfishes are native to all continents except Africa and Antarctica and are most common in North America. Of the approximately 625 species found on earth, over 400 live in North America, with the southeastern United States being the center of global diversity. We see this same pattern of biodiversity with other temperate aquatic organisms such as freshwater fishes and mussels. The other area with a major crayfish fauna is Australia with over 150 species.Georgia is home to approximately 70 species of crayfishes which ranks it fourth in diversity behind Alabama (~100), Mississippi (~80), and Tennessee (~95). Crayfishes exhibit high rates of endemism, which means that many species occur only within a specific and often small geographic area. For example, sixteen of Georgia’s species occur nowhere else in the world and many are restricted to a single or small number of river systems within the state.The crayfish fauna of Georgia is well known because of the seminal work of Dr. Horton H. Hobbs Jr. titledFor nearly 15 years after Hobbs (1981) publication, little work was conducted on Georgia crayfishes. In 1996, Taylor et al. published a paper outlining the conservation status of all the crayfishes found in the United States. In this article, the authors suggested that as many as 22 of the species found in Georgia were imperiled in some way. As a result of these findings, the Georgia Department of Natural Resources initiated studies to better assess the conservation status of Georgia crayfishes. This work, combined with a follow-up conservation paper in 2007 by Taylor et al., led to the protection of 20 species under Georgia’s Endangered Wildlife Act.There is still much to learn about Georgia crayfishes and new information on life history, ecology, and distribution patterns continues to be discovered. We encourage you to email email@example.com with photographs and locations of crayfishes that you observe to help us update our database.
Ecology & Life History
Crayfishes can be found in a variety of habitats including streams, lakes, marshes, roadside ditches, cave systems, and even in burrows that are sometimes well away from open water. In Georgia, particularly the northern part of the state, most species inhabit streams. As you move farther south in the state however, more and more species can be found in temporary habitats such as ditches and wet-weather ponds. As water recedes during dry times, the species in these habitats will burrow into the ground.All crayfishes are capable of burrowing but some spend most of their lives in burrows. The latter, called primary burrowers, construct complex burrow systems and seem to be constantly moving soil around (Fig. 1). Their burrow openings are usually marked by mounds of soil referred to as chimneys (Figs. 2, 3). In Georgia, primary burrowing species are typically found in low, wet (“swampy”) areas, often in the floodplains of streams or rivers. Since these species are difficult to observe, they are poorly studied and several appear to be quite rare. About 15 of Georgia’s species are considered primary burrowers. Secondary burrowers spend part of their lives in open water and retreat to relatively simple burrows for protection during the daylight hours; they may also use burrows to survive dry periods. Holes in creek banks that are sometimes called “snake holes” are more likely created and inhabited by a crayfish; snakes do not create their own holes. In some crayfish species, females burrow when it is time to release their eggs (tertiary burrower).There are approximately 30 obligate cave crayfish species in North America, two of which live in Georgia. Most of the cave species are not pigmented and some are blind; they rely on tactile and chemical senses to negotiate their lightless habitats. In Georgia, the Dougherty Plain Cave Crayfish is found in underground regions in the southwestern part of the state. The Pallid Cave Crayfish was discovered recently and is only known only from two locations in Brooks County.Crayfishes are typically inactive during the day and come out at night to feed. It has been said that “crayfishes eat everything and everything eats crayfishes.” This is largely true, and hence, crayfishes play a pivotal role in freshwater food webs. Virtually all the energy that sustains animals comes from nutrients produced by the photosynthetic activity of green plants. In stream and river systems however, there are often few plants growing directly in the water. Where does the energy come from that powers stream and river food webs? Well, most of the plant material that supports aquatic organisms comes from sources outside of the stream such as leaves and woody debris from trees. Crayfishes will eat this plant matter as well as insects that eat plant matter. Thus, they are converting “plant” energy into protein in the form of a large tail muscle and thereby become an important food source for a host of organisms. Crayfish predators include raccoons, kingfishers, wading birds, otters, minks, and of course, humans. There is a group of snakes of the genus Regina that are crayfish specialists. One Georgia species (Queen snake) eats only freshly molted individuals while others eat hard-shelled individuals. Crayfishes are a major food source for many fishes, particularly the basses and sunfishes in the family Centrarchidae.Like other arthropods such as insects and spiders, crayfishes have a rigid exoskeleton. This hardened outer covering acts like our skeleton by providing attachment points for muscles, thereby facilitating movement. The problem is that the exoskeleton is largely composed of non-living tissue and therefore does not grow. In order for crayfishes to grow, they must periodically shed (molt) the exoskeleton. Once they molt, their body is soft (claws are useless) and they are extremely vulnerable to predation. The new exoskeleton will harden in about two days.A great video that depicts a crayfish molting can be found at: https://thekidshouldseethis.com/post/a-molting-blue-crayfishMale crayfishes (and possibly females) have a somewhat unusual pattern of molting once they become adults. Males molt back and forth between a reproductive form (Form I) and a non-reproductive form (Form II). The primary differences between Form I and Form II males are the development of the claws and the shape of the reproductive organ which is called the first pleopod, or gonopod (see “Crayfish Identification” below for more detail). In juvenile and Form II males, the gonopod appears to be the same color and consistency throughout its length and has more blunt and rounded features. In Form I males, at least one of the terminal elements is corneous (appears yellowish and brittle, Figs. 5, 6).Reproduction usually occurs during the spring and fall, but males in reproductive condition may be found at any time during the year. When female crayfish are ready to lay eggs, they usually find a secure hiding place and hence are rarely encountered. When the eggs are released, the female attaches them to her swimmerets (pleopods) and is said to be “in berry” (Fig. 7).Upon hatching, the juvenile crayfish are attached to the mother by a thread (Fig. 8). After the young molt for the second time, they are free of the mother, but stay close and will hold on to her for some time. Eventually they move off on their own. Crayfishes molt six or seven times during their first year of life and most are probably able to reproduce by the end of that year. They molt once or twice a year for the remainder of their lives. Stream dwelling species live only about three years in Georgia. Recent life history studies of burrowing crayfish indicate that they live at least 7-8 years and cave crayfishes may live as long as 20 years!Most stream crayfishes reach a total body length of no more than 3–4 inches. With the claws included though, some individuals can appear quite large. The largest species in Georgia are in the genus
While Georgia’s crayfish fauna is very diverse, it also threatened. Twenty species (~28% of Georgia species) are considered imperiled and are protected under Georgia’s Endangered Wildlife Act. Threats to crayfish are in part, similar to those of other aquatic organisms. For example, siltation from poor land use practices can fill spaces used by crayfish as daytime refugia and also limit good habitat for aquatic insects that crayfish feed upon. As mentioned above, many crayfish species are known from only a small geographic area. Just think of a species that is known from only a few populations, like many of Georgia’s rare crayfish species. An unforeseen event such as a chemical spill would sharply reduce the total numbers of a given species and increase the probability of local population loss (extirpation) or in some cases global extinction.The introduction of nonindigenous invasive species is likely the most serious threat to Georgia’s crayfishes. Many people think of things like kudzu and pythons as being invasive. That is true, but in the case of crayfishes, just moving a species from one river system to another could have serious consequences. Crayfishes fight for space and other resources. If a species is introduced to a new river system, it has the potential to take over the new area if it has traits such as faster and larger growth, the ability to produce more young, or by being more aggressive. If an introduced species is better at taking over the best habitats, the native species will struggle to survive. Never move crayfishes (or any aquatic organism) to a waterbody away from the one in which it was captured. Whether you are an angler using crayfish as bait or you just purchased a sack of live crayfish for a crawfish boil, preventing the release of crayfishes into ponds, streams, or other waterbodies may be the single-most important thing you can do to protect Georgia’s rich crayfish fauna and the myriad of species that depend on it.Find out more at Conserving Georgia’s Aquatic Species.
As with any group of organisms, the new student of crayfishes may find it difficult to distinguish between some species. Fortunately, there are extensive distribution records for crayfishes in Georgia. This is important because when attempting to identify an unknown crayfish, it is possible to dramatically reduce the number of choices based simply on the location that the crayfish was observed or captured. Thus, one way to try to determine the species of crayfish that you have seen is to visit the crayfish page on the Georgia Biodiversity Portal. You may search this database by county, quarter-quad, or watershed, and by doing so, generate a list of possible species in your area. Once a list is generated, you can click on an individual species name, which will take you to the account for that species. Each account includes a description, a color photo, and a range map. When first learning the crayfishes, you may just need to start at the beginning of the list you generated and click through the various species accounts to find your best match.Alternatively, you can attempt to identify your crayfish using a dichotomous key, also accessible through the crayfish page on the Georgia Biodiversity Portal. On the dichotomous key page, you will find a clickable drainage map that will take you to a list of species and the dichotomous key for your particular drainage. There are also tips for using keys, general information on crayfish anatomy, and discussion of the primary characteristics used for identification.
Mostly, crayfish reside in fresh water, especially where the water is running, such as rivers, streams, and brooks. They prefer running water as most of them cannot survive in polluted water. Stagnant or standing water bodies are most prone to getting dirty and polluted as they do not have access to cleaner water sources which can flow in and wash away polluted, stale water through aquatic outflows.However, certain crayfish species such as theAustralia is host to about 100 species of crayfish including marron, red-claw crayfish, yabby, Tasmanian giant freshwater crayfish, and western yabby. Madagascar, as a geographically significant crayfish habitat, is home to seven species falling under the genusNorth America comes out as the geographical habitat of the maximum species of crayfish, with a whopping 330 species belonging to nine different genera of the