Dueling Crabs in Thailand - Observation of the Week, 6/7/22

Our Observation of the Week is this pair of Macrophthalmus tomentosus crabs, seen in Thailand by @plains-wanderer!

“Most other kids my age in the area I grew up in carried slingshots around to shoot animals for fun, but my idea of having fun was to try identifying animal species & see rarely seen animals,” Wich’yanan “Jay” Limparungpatthanakij tells me. “I would steal slingshots from those kids & hide them away whenever I had a chance, so they couldn't hurt animals, at least for a while.”  Wich’yanan grew up in the countryside of Thailand and while the was into all kinds of organisms, the only comprehensive field guide that was available to the public covered birds  (A Field Guide to the Birds of Thailand by Boonsong Lekagul & Philip D. Round, published in 1991), so he was able to study and identify them more than most other organisms. 

His interest in birds continued into his time at Mahidol University, where he focused on the ecology of avian mixed-species foraging flock, and through to this year, when he participated in the Global Big Day. And “while scanning for shorebirds on an intertidal mudflat west of Bangkok suburbs,” Wich’yanan spotted the crabs you see above.

I had never a photographed this species engaged in such an action before, so I took a few shots. It's one of the many species I learned about from iNaturalist. I submitted a few observations of this same species to iNaturalist last year, not having a clue what species they were. Big thanks to @rueangritp, who is a crab expert, for adding the initial species identification, as well as confirming & correcting other crab identifications I attempted to do on my own.

Not much is known about crabs in this genus but they are in the same superfamily (Ocypodoidea) as fiddler crabs and ghost crabs, and Wich’yanan captured two males locked in combat in his photo. 

An iNat member for nearly three years, Wich'yanan’s (above) recently worked on research for @rongrong_a's PhD study on bird communities in the agricultural landscape in the Central Plains of Thailand. The two of them also started the Tangled & Trapped project on iNat as a way to collect data on animals caught by human objects. And he’s also trying to improve the data quality and computer vision model in Thailand.

By uploading photos to iNaturalist, it has been much easier for me to look for my own sightings. I think I've learned to identify invertebrates, plants, & other organisms more quickly than ever. I think I no longer have plant blindness! The feature “suggest species” is super useful and handy, but oftentimes it suggests similar species occurring in developed countries where more people submitted data but are out of range. This motivates me to submit media as frequently as possible to help improve it, at least locally. I've also been urging people to add their sightings to relevant iNaturalist projects.

(Photo of Wich'yanan by Rongrong Angkaew)

- You can follow Wich’yanan on Twitter and Instagram.

- And check out his research here.

- Here’s a Macrophthalmus banzai crab (same genus, different species) doing some pincer waving on a mudflat in Japan.

Posted on June 7, 2022 10:07 PM by tiwane