Crab in freshwater in Chiapas, Mexico

Excerpts from Jim Conrad's
Naturalist Newsletter

from the May 19, 2008 Newsletter written in the community of 28 de Junio, in the Central Valley 8 kms west of Pujiltic, Chiapas, MÉXICO
about 800 meters in elevation, ± LAT. 16° 18'N, LONG. -92° 28'W.
FRESHWATER CRABS

I didn't know that freshwater crabs existed until I heard that men here go out at night to harvest them from the area's pesticide-polluted canals. I was told that the crabs emerge only at night. You find them by shining a flashlight into the water, and sometimes you catch whole buckets of them. This week, in the middle of a hot, sunny morning, finally I saw a crab in a canal littered with empty pesticide bottles.Of course that's him above.

Eliezer is the main crab collector here and he says they get a bit larger than the one in my hand but not too much. He says that now, just as the wet season is beginning, is when they breed, and that females produce huge numbers of offspring. When he and his friends catch them they check to see if they're carrying eggs and if so they let them go. I asked him what the crabs eat.

"Those little fish in the canals," he said. "You see the crabs with their rear ends up against the bank and facing out into the water, with their arms spread wide and their claws open, and when a fish swims in front of them they grab it. They also eat Chicozapote fruits that fall into the water."

I have no literature on crabs here and can't browse the Internet so I'm very interested in knowing how special our freshwater crabs are. What's their name and are they listed as rare or endangered? If it's particularly rare or endangered possibly the community can get some international help protecting them. I wouldn't mind seeing a freshwater crab reserve set up here.

In case you want to try identifying the crab yourself, a different view from the above is shown below:

from the May 29, 2008 Newsletter written in the community of 28 de Junio, in the Central Valley 8 kms west of Pujiltic, Chiapas, MÉXICO
about 800 meters in elevation, ± LAT. 16° 18'N, LONG. -92° 28'W.
FRESHWATER CRABS UPDATE
About an hour before I left 28 de Junio an International Human Rights Observer brought me an orange-red crab just like the one shown above.

A good thousand feet from any canal, the crab had been crossing the dirt road running through town. When one of the local men heard us expressing surprise that it could wander so far from water, he laughed and said he'd found them atop the nearby hill!

In response to the last Newsletter, tropical-cave explorer Sleazel in Florida writes that "Freshwater crabs are super common in Central America, I've seen lots of them wherever there are caves, so I think calcium is the issue." Louise in Cyberspace sent links to online articles on freshwater crabs in Panama. Answering my question as to whether anyone was paying attention to our Chiapas freshwater crabs, Marc in New York referred me to an article in the Journal of Crustacean Biology, Vol. 18, No. 1 (Feb., 1998), with the title of "Six New Species of Fresh-Water Crabs (Brachyura: Pseudothelphusidae) from Chiapas, Mexico," by: Fernando Alvarez and Jose Luis Villalobos.

Holy mackerel, but what a bunch of savvy folks read this Newsletter!