Red Jamaican Crab

This particular crab is famous as the inspiration for Sebastian in the ocean movie The Little Mermaid. Below, readers can explore facts about this well-known species of crab. This includes its preferences when it comes to habitat and diet, and the behavior of its young. For instance, for the first three years of a red Jamaican crab’s life, it lives in other crabs’ burrows. 

Appearance 

Throughout the species, there are four different distinct colors, red, yellow, and green. They are traditionally darker on their upper sides than on the undersides. This is known as countershading and is usual to avoid predators while in the water. The dark side blends in with the dark ocean floor and the light side with the sun coming through the ocean’s surface. These crabs also have the traditional profile of a crab that most readers can expect. They have eyes centrally located and longer front claws that extend to crab prey. 

These crabs are nocturnal, meaning that they spend most of their lives moving around when it’s dark outside. This prevents the crabs from drying up in the hot sun, as noted by “The Cayman Crab Fly Revisited — Phylogeny and Biology of Drosophila endobranchia.”

Credit: Ceilidthbear

Habitat 

This crab is found throughout the Caribbean and as far east as Barbados. It prefers warmer waters and has been spotted in Florida and even in Nicaragua, but these reports are few and far between. There are populations off the Colombian coast as well as in the Swan Islands around Honduras. 

Interestingly, the crab has been sported at an altitude of 980 feet, or 300 meters, on land. In Jamaica, it was found at 3,300 feet or 1,000 meters. 

The crabs grow around 1 inch per year when they’re young. They reach maturity around five years of age and can live for another five. 

Diet 

Crabs are known to search for food along the ocean floor, eating anything with some substance that they can find. This includes parts of other crabs, squid, fish, and starfish. They also enjoy eating whole smaller organisms like worms. These crabs are terrestrial. This means that they live primarily on land but still visit the sea on occasion. This is going to influence their diet.

Reproduction 

When the red Jamaican crab lays its young, it does so in the sea. The larvae live as plankton as they grow. They’re quite small at first, sometimes returning to land. This creates a phenomenon known to turn roads red. The first three years of the crab’s life are spent living in burrows created and inhabited by other crabs. They also eat the food supplied to them by these older crabs, as noted in “Why do we see Crabs in the Quill?”

One female may carry around 85,000 eggs at one time. These are released during mass migrations, as noted in  “Reproduction of the black land crab, Gecarcinus ruricola, in the San Andres Archipelago, Western Caribbean.”

Threats 

The red Jamaican crab is at threat from the same sources as most ocean-dwelling species. This includes changes in ocean current, temperature, and the level of the water itself. Coastal erosion is also an issue that these creatures contend with, as is human encroachment on their coastal habitats. 

Credit: Arcus C. Stensmyr, Regina Stieber & Bill S. Hansson

Common predators include fish and eels (especially when the crabs are young) as well as larger types of fish, some sharks, and other large ocean species. 

Interestingly, there are two different organisms that commonly use the red Jamaican sea crab as a host. These are commensal flies of the genus Drosophila. The first is Drosophila carcinophila (Source: “Flies’ lives on a crab”) and the second, noted in 1967, is Drosophila endobranchia. The flies spend most of their lives on the crabs. This allows them safety from most predators due to the speed of the crabs and their willingness to flee at a moment’s notice. 

The flies lay eggs around the crab’s eyes that then migrate to the crab’s nephritic pad. There, they live and feed on microbes. They move to the crab’s gill chamber and into the mouthparts throughout their lives as well, as noted in  “The Cayman Crab Fly Revisited — Phylogeny and Biology of Drosophila endobranchia.”

Facts about the Red Jamaican Crab 

• Two species of flies live on the crabs’ bodies. 
• The first three years of the crab’s life are spent living in other crabs’ burrows. 
• The red Jamaican crab is commonly found in the Caribbean, west of Cuba, and as far as Barbados.
• The crab is also sometimes referred to as the zombie crab. 
• They can be four distinct colors: black, red, yellow, and green.
• These crabs are darker on their upper side than their underside. 

FAQs 

 (featured image credit: P.Lindgren)