Is your Crab a Halloweener? Common Mistaken Identities

This post is based on research of description, and probably photographic matches of 4 commonly confused crabs. One of which is an actual Halloween Moon Crab, the other three are of different species and even genus. These were chosen based on my opinion of which were confused the most in name, photo, description and locations.



Rainbow Crab (Cardisoma armatum)
This crab (and just recently I realized other species of Cardisoma) I see photographically confused with Halloween crabs most often. This crab is from the same family (Grecarcinidae) but a different Genus, Cardisoma.
This crab goes by Patriot crab, and Moon crab (confusionnn).
Far from Halloween crabs, these babies are from the coast of Western Africa. They can reach 7 inches wide on the carapace (back).
Color difference is that these crabs bodies are more blue/violet. The have whitish claws and underbody, red orange legs, and most notable other than the body; they have light eyes.



Purple Land Crab (Grecarcinus ruricola)
I include this crab because its in the same family as the two listed below (includes Halloween Crabs), and because the name has gotten mixed with Halloween Crab photos often.
Also goes by the name Zombie Crab and Black Land Crab.
This one is found in the Caribbean, Western Cuba, all the way to Eastern Barbados as well as other places here and there.
G. ruricola can reach around 5 inches wide on the carapace (back). They have multiple color morphs: Black, yellow, red, and green. As you can see in the photo they are very different from those two below, they are dark all over and do not have the large sections of bright colors. Rather, they are darker, with bright accents.


Blackback Land Crab (Grecarcinus lateralis)
This is the most commonly confused I have seen in person. Twice now in pet stores near me I have seen these advertised as Halloween Crabs.
These also go by the name Bermuda land Crab, and get confused with the Christmas Island red land crab. Also from the family Gecarcinidae, this crab is along the Atlantic coast from South Padre Island, Texas; to Venezuela. Also found in the Florida Keys and Caribbean. They stay mainly along the dry sands, 25 feet above high tide.
These crabs reach up to 4 and a half inches wide along the carapace (back). They're are mostly reddish, orange, or lighter all over, aside from the large black spot on their back. This spot varies in size and shape.




THIS IS A HALLOWEEN MOON CRAB (Grecarcinus quadratus)
This is the crab I have. Part of the family Gecarcinidae, along with G. ruricola and G. lateralis.
Also goes by the names halloween crab, moon crab, white spot crab.

This crab comes from the pacific coast from Mexico all the way to Peru, Mainly known as from Costa Rica. They live in mangroves, Rain forests, and along sand dunes.
Said to get to 2 inches wide along the body, but have heard up to 4.
Has a dark purple/black carapace (body), mostly purple claws, orange legs and lower body (leaning more towards red or yellow depending on male or female it is assumed)
Distinguishing accents are noted as BLACK eyes, with two red, orange, yellow, white, or even maroonish spots, one by each eye; as well as commonly a yellow or orange "mouth spot" or "mustache". and two white or yellowish spots on the lower back.