Crawfish are almost our totem animal in Louisiana. A big, red crawfish held aloft in a clenched fist is the symbol of Cajun Power.
And crawfish love isn’t confined to South Louisiana. Each May, Shreveport — that most un-Cajun of Louisiana cities — holds Mudbug Madness, a four-day blowout on the banks of the Red River.
But there is a lot more to crawfish than eating them. And there are a lot more species of crawfish than the red and white crawfish — the ones most commonly eaten by humans.
Worldwide, scientists have identified over 450 species of freshwater crawfish. North America is crawfish headquarters, with 353 species — 95 percent of which are found in the southeastern U.S.
Jerry G. Walls, author of the beautiful 240-page book Crawfishes of Louisiana, lists 39 species as occurring in Louisiana. Among those are the unusual species dubbed the devil crawfish, Cambarus diogenes, and the painted devil crawfish, Cambarus ludovicianus.
Both species, if they are separate species, are big animals, growing as large as the familiar red swamp crawfish cooked at crawfish boils. They are identical to each other in every way except body color, something that makes astacologists (crawfish experts) very nervous about declaring separate species instead of one.
The devil crawfish is an attractive green color, set off by bright, wine-red margins at the edges of each joint in the shell. The painted devil crawfish is even more attractive, being the same overall color, but with the addition of several yellow, orange or red length-wise stripes running down the body and tail.
One of the most-noticeable characteristics of both devil crawfish species is the massive spade-shaped pincers. These are not merely decorative, but put to good use by these industrious excavators.
Few people know that crawfish in general are as much creatures of the underground as they are creatures of the water. Scientists group all crawfish into three categories, based on their digging proclivities: primary burrowers, secondary burrowers and tertiary burrowers.
Beginning with the last first, tertiary burrowers are those that only resort to digging burrows when surface waters dry up, especially during the hottest part of the year. Their burrows tend to be simple and short, just deep enough to find moisture to keep their gills wet. Chimneys, made of mud carried from the burrow by the crawfish and placed around its entrance tend to be very small or even nonexistent. Some simply plug the mouth of their burrow with a ball of mud.
During their several-month period underground, females lay eggs and hatch their young, which cling to hair-like pleopods found under the adults’ tails. Winter rains or river rises flood their burrows, flushing adults and young from the burrow to begin the part of their life cycle spent in surface waters like ponds, bayous and ditches.
Both red swamp crawfish and white river crawfish, by far the most commercially valuable species for human consumption, are tertiary burrowers. Under conditions of permanent water, some tertiary burrowers complete their life cycles without burrowing.
Secondary burrowers spend much more of their time, often most of the year, underground. Their burrows are simple or complex, shallow or deep, and most of these species venture regularly into surface waters for feeding or mating. Many of the crawfish species found in ditches are secondary burrowers.
Primary burrowers, the group to which devil crawfishes belong, spend most or all of their lives in burrows that extend down to the water table, sometimes 20 feet deep. Their burrows also are complex, with side burrows and multiple openings to the surface. Not all of the entrances will have mud chimneys.
Although they do turn up occasionally in commercial crawfish catches, it is rare to find an adult devil crawfish outside its burrow except when they hunt for food, when males walk about looking for females, when extensive flooding covers an area or when females leave to burrow to release their young into surface waters.
Mating takes place in the burrows, and the eggs — which are cemented to the female’s pleopods — are incubated in the burrow. Females must be in the soft-shell stage after a molt to mate successfully. Such females release pheromones that signal to males they are receptive. The male deposits tiny packets of sperm in the female, which will fertilize her eggs internally before they are laid.
Females can produce up to 200 eggs. Young devil crawfish will undergo two or three molts before they stop clinging to their mother’s pleopods and are ready to venture out on their own. Devil crawfishes mate in the fall, but wait until spring to lay their eggs.
Young devil crawfish that live in open water are eaten by a wide variety of fish and other predators with just as much relish as any crawfish species.
Devil crawfishes are considered to be detritivores: They eat rotting plant matter that is covered with a protein-rich layer of bacteria and other microbes. Research indicates that at least 60 percent of their diet is vegetation, with the rest including items such as worms, insects, snails and dead animal matter.
Devil crawfish’s burrow chimneys, made of sun-baked balls of clay, can become hard enough to dull lawn mower blades. They are considered nuisances on golf courses, maintained cemeteries and home yards.
Research done in Illinois shows that devil crawfish are very loyal to the burrows they work so hard to build. Individual crawfish were marked when they came out of their burrows to feed and were tracked for two months. Over 82 percent of the crawfish used their same burrows. When a new crawfish was found in a burrow, it was larger than the previous resident, suggesting that previous owner was out-muscled. Devil crawfish dig their burrows at night.
The name “devil crawfish” is interesting, as is another of its monikers: “coffin cutter.” Legend has it that they use their large claws to burrow down and cut into coffins to dine on human flesh. While they are strong diggers and many South Louisiana cemeteries in low-lying areas are dotted with the mud chimneys that mark their burrows, there is no evidence that they enter coffins.
The book, Crawfishes of Louisiana, is destined to become a classic, as are the now hard-to-find Louisiana Birds and The Mammals of Louisiana and its Adjacent Waters by George Lowery Jr., The Amphibians and Reptiles of Louisiana by Harold Dundee and Douglas Rossman, and Wildflowers of Louisiana and Adjoining States by Clair Brown.
Every species of crawfish in the book is beautifully photographed by the author’s wife Maleta M. Walls. If the book, published by LSU Press, isn’t available in your local bookstore, it can easily be ordered through the Internet.