Blue Land Crab - No Vacancy

One morning my next-door neighbor told me a giant crab went after her chihuahua the previous night. She told me to watch out, but I was not too concerned about a crab. The next day I went out my backdoor to be greeted by the biggest, and most beautiful crab I have ever seen in my life! The crab seemed much more scared of me than I was startled by it, so after taking a quick photograph, I left him alone so he could find a new home.

Leave, this crab did not. We had two more encounters over the next few days, each time in a new location of my backyard: behind the sandbox, in the garden, and under a bucket.

I decided to do some research into this ginormous crab to learn more and hopefully figure out what this crab was doing in my backyard?

What is the name of this crab? Cardisoma guanhumi or the blue land crab.

Where is this crab native to? Found in Brazil, Colombia, the Caribbean, the Gulf of Mexico, Florida, Bermuda and the Bahamas.

How big do they get? 6 inches in width.

What do they eat? Leaves, fruits, insects, other crabs.

What is their migration ecology? Heavy rainfall in spring sparks a migration that leads to their mating grounds.

Reproduction? Throughout July and August females will carry their eggs externally for about 2 weeks. The female will then need to return to saltwater for the larvae to survive.

Some of their interesting characteristics:

  • One claw is massively bigger than the other in males.
  • Be extremely careful with these crabs, they are not dangerous but can give a serious pinch if provoked.
  • The blue land crab disappears during the winter to hibernate down in their burrows to molt and will seal the burrow with mud to keep out intruders. They only molt once a year and can molt up to 60 times.
  • Crabs measuring 5 to 6 inches can be approximately in their 20s.


Given this information, I believe our new backyard guest is most likely a male in his 20s. Since it is June and there have been recent heavy rainfalls, I expect he is in search of a mate. Don’t be alarmed if you happen to find one in your backyard, be assured they will be on their way soon.

Photo credit: Blue land crab by Kayla Caldwell


Category Tag(s): Nature Blog