Mike Gigliotti Curator

Joined: Apr 4, 2018 Last Active: Jun 5, 2024 iNaturalist

Marine invertebrate biologist with a special interest in brachyurans (also known as true crabs). Ph.D. student at Florida Institute of Technology. While I will take a picture of anything that crosses my path, I definitely have an affinity for macro shots of the smaller world around us.

Here is a growing list of online sources (from the informal to the professional) that I've found useful, both generalized guides and guides/papers specific to crabs. I included some of these here just so I know where to always find the links. Despite the fact that some of these may use outdated taxonomy, their value as resources for visual identification still remains. If you investigate any of these links and find a single glaring issue, please let me know!

Atlas of Living Australia

Crab Database
(Ondřej Radosta, 2016)
Ondřej is known as @ondrej-radosta here on iNaturalist

Shelf Invertebrates from the Northern Gulf of Mexico
(Perry and Larsen, 2004)
Persephona mediterranea would be one of the exceptions in this guide (that I know of) since the picture they use is actually Persephona aquilonaris. Click here if you want an updated look at these two species.

True Crabs, Hermit Crabs, and Horseshoe Crabs of South Florida Reefs
(Florent Charpin, 2004-2019)

Land, Mangrove and Freshwater Decapod Crustaceans of Mayotte Region
(Bouchard et al., 2013)

Coastal Crabs: A Guide to the Crabs of New Zealand
(Wilkens and Ahyong, 2015)

Majoidea Crabs: Guadeloupe Island and the Lesser Antilles
(Carmona-Suárez and Poupin, 2016)

Ghost Crab Distributions, World Map
(Sakai and Türkay, 2013)

The three species of Acanthocyclus:
A. albatrossis
A. gayi
A. hassleri
(Meyer et al., 2013)

Invertebrates of the South Atlantic Bight
(Southeastern Regional Taxonomic Center)

Anomura and Brachyura of Cuba
(García and Capote, 2015)

Crabs of Hawaii (and a little extra)
(Marine Life Photography, Keoki Stender, 2018)

Sesarmid Crabs of Singapore
(Ron Yeo, 2013)

Crustacean Identification, Oregon to Southeast Alaska
(Pacific Northwest Shell Club)

Ocean Shore Crabs of New South Whales
(Catchment Management Authority)
At least one outdated taxon name here.

California Crabs, Tricky ID Flashcards
(University of Washington, College of the Environment)
Brought to my attention by @jschaefer

Photoblog of the Queensland Coast
(Andrew Mitchell, 2018)
Andrew is otherwise known as @coenobita here on iNaturalist

Achelous and Portunus in Brazilian waters
(Rodrigues et al., 2017)

Molecular phylogenetics of various members of Portunoidea
(Nathaniel Evans, 2018)

For checks on the most up-to-date marine invertebrate taxonomy, I find the World Register of Marine Species (WoRMS) to be the easiest to use.

When photographing specimens, I highly recommend utilizing as many angles as possible. This is certainly not always an option, but anything that is small, close, or easily handheld (i.e. manageable) is a good candidate for multiple pictures. For example, my favorite group, the true crabs (Brachyura), are often most easily identified from the carapace, eyes, claws, and back legs, and when certain species look nearly identical at a passing glance, it is best to catch these diagnostic characteristics at multiple angles.

I also believe it is important to use consistent and concise language as often as possible when referring to animal anatomy. I try my best to give details whenever I suggest an opposing identification on iNaturalist, and for anyone who is not familiar with directional terms in anatomy (that I often neglect to use myself), I decided to provide a very unprofessional guide here:

anterior or rostral - towards the front of the body
posterior or caudal - towards the back of the body
dorsal or superior - the top surface of the body
ventral or inferior - the bottom surface of the body
medial - towards the midline of the body
lateral - away from the midline of the body
proximal - towards the center of the body
distal - away from the center of the body

And because crabs are my favorite group, here are just a few anatomical terms that apply to them:

carapace - the hard shell covering the body
pereiopods - the five pairs of walking legs for which the order Decapoda ("ten legs") is named
chelipeds - the two claw-bearing legs, which are considered two of the ten pereiopods
chela - claw, and the plural form is chelae
dactylus - movable finger of the claw
propodus - fixed finger of the claw
anterolateral or marginal teeth - refers to the spines on the sides of the carapace (if present)
rostral teeth - refers to the spines on the front side of the carapace between the eyes (if present)

If you'd like to use one of my images for any reason, please send me an email at mikegigliotti6 [at] gmail [dot] com.

Cameras used:
iPhone 5c (2014-2016)
iPhone 7 (2017)
Olympus TG-5 (2018, April 11th to May 20th)
iPhone 7 (2018, May 23rd to June 23rd, miscellaneous onward)
Olympus TG-5 (2018, June 22nd and onward)

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