Crayfish don't all look alike: Clawing for an identity
By Tony Bridges, The News Herald, Panama City, Fla.
Nov. 9, 2007

Nov. 9--PANAMA CITY -- The identity crisis soon may be over for the Panama City crayfish. Until now, popular wisdom has held that the mud-dwelling critters were virtually indistinguishable from any other crawdad with two claws and a tail.

But state crustacean experts debunked that theory Thursday.

They held a series of seminars at Gulf Coast Community College to show off the stripes, spots and unique shapes that set the native species apart from the rest. By mid-afternoon, more than a dozen private consultants and public employees had learned the difference.

"Some people have gotten the impression that the Panama City crayfish is very difficult to recognize," said Paul Moler, a retired state research biologist who led the workshop. "That's not true."

Normally, small variances between species wouldn't matter to most folks, except that Panama City crawdads are protected by law, and other species are not.

The Florida Fish and Wildlife Conservation Commission, or FWC, lists them as a "species of special concern" and is considering upgrading them to "threatened." That means it is illegal to kill the animals, develop land where they live, or destroy their burrows to maintain drainage ditches or utility lines.

Of course, people have to be able to recognize them to follow the rules. And for a while, even state experts had trouble doing that.

The accepted method for identifying a species of crayfish has been to examine the gonopods -- the reproductive organs -- of male specimens under a microscope, looking for differences in shape and color, Moler said.

Males have two gonopods that fold up between their legs.

The problem is it is nearly impossible to check live animals in the field, so they usually are killed, preserved in alcohol and examined in a lab. But the differences in gonopod shapes are minute, and alcohol fades all specimens to gray, which eliminates any identifying colors, according to Moler.

The solution required a simple change in perspective: Make the identification based on geography and appearance, instead of the reproductive organs.

FWC has outlined the historic habitat range of the Panama City crawdad. It stretches from the western edge of Panama City to a little east of Callaway, and from the tip of Bayou George to the north side of Parker.

Crayfish found outside that range can't be the Panama City variety, and only four kind of wetlands crayfish live inside the range, said David Cook, an FWC biologist working on the state's crayfish management plan.

One of those species rarely ventures above ground, and another lives only in swamps. That leaves the Panama City crawdad and the stud crawdad.

Telling them apart is "really just a question of education," Cook said.

The Panama City species has a stripe running down its back and tail, a light-colored carapace with dark spots, medium to large claws and a broad rostrum, or beak, between its eyes. The stud species is slimmer in the claws and rostrum and has white spots on a darker carapace, along with two large, dark dots on each side.

The biologists had live examples in plastic Glad containers for Thursday's seminar.

"Wow, look at him," said attendee Roxanne Jones, a scientist with JR's Environmental Consulting, as she pointed at a Panama City crawdad. "He's beautiful."

To her, the difference between the local species and the others was clear.

"Once you've seen them and evaluated what to look for, it's not hard," she said. "I don't think there will be any problem."