Clawless Verm Crab
Basic Information
Anatomy
The clawless verm crab is like it states: clawless. Unlike other crustaceans, it does not have the defense of hardened claws to keep creatures away from itself or to capture prey. Another unique trait that this crab has is its exoskeleton. Rather than being entirely covered, there is a section of its body that does not have an exoskeleton, and that is the top of its head. It is a gelatinous consistancy held in by a thin membrane. This does not leave the crab defenseless, though, as a part of its exoskeleton hooks under its belly and up above its head. This part of the exoskeleton, referred to as the umbrella, will snap shut in particular instances: when the crab feels threatened, or when small enough prey has crawled in. The prey will be consumed through the membrane of the crab's head as that is also where its stomach lies.
The carapace of the clawless verm crab is a bright red. It is incredibly sturdy for its size, though it is still considered fragile to most who find them. Male clawless verm crabs sit, at largest, at around 2 inches (5.08 cm) in length. The smaller females average about 1.5 inches (3.81 cm).
Like all crabs, the clawless verm crab shed their shells as they grow. If they have lostany limbs during their present growth cycle, it will have regrown after they molt. If they lost their umbrella shell, this, too, will regrow. Newly molted crabs are very vulnerable because of their soft shells. They are reclusive and hide until the new shell hardens, often burrowing into the sand to hide.
Genetics and Reproduction
Clawless verm crabs live short lives, usually no longer than two years. Male verms will snap shut their umbrella shells and but into one another as a form of courtship. The larger males will often knock the smaller males prone and they will either be left for dead or will eventually turn themselves over. The females will mate with the males that remain staning. The females occupy the burrow of their chosen mate and it is here that she will lay her clutch. The size of the male verm is directly correlated with the size of the burrow, which in turn relates to the environment and temperature for the eggs. The ability to knock another male prone indicates to the females that the male is overall healthy and strong, which implies the male will help with the production of viable offspring. The female will carry her eggs in a mass inside the umbrella shell on her head. The membrane used for digestion hardens slightly during this time so she does not digest her young. She remains in the burrow with her umbrella closed for a two-week gestation period, after which she will wander to the sea during low tide and release her eggs. Her young will remain in a planktonic state in its larvae stage for two more weeks after.
Ecology and Habitats
The verm crab species can be most often found in salt water marshes or along a soft-sand beach. The clawless verm crab, though, is exclusively found on soft-sand beaches, as they are particularly vulnerable to predators in the swamplands without their claws.They are the most common crab found along most beaches and they play an important role in the health of the environment. They eat dead/decomposing matter (detritus) and are also a food source for many other coastal animals. They also help preserve the ecosystem by burrowing in the mud of the beach and creating a maze of tunnels that add oxygen to the plant life along the coast.
Dietary Needs and Habits
While the clawless verm crab subsists largely on detritus of decomposing creatures along the oceans edge, they also have a unique method of capturing prey. They will partially bury themselves in the sand, leaving their umbrella shells open. When they feel prey walking along the thin membrane on their head that covers their stomach, they will snap the umbrella closed, trapping their prey inside and digesting it through the membrane. Because of this, they also feed on small parasites and bugs that make their homes in the sand and even consume plankton that gets washed into their shells while they are on the beach.
Whilst the Vermillion Shoresare known for their bright red waters, the sands of many beaches are covered in red waves of their own. These little crabs will scitter across the sands, hundreds of thousands of them! Not long after they hatch, the waves will bring them to the shores. It is a bizarre sight indeed.
Additional Info
Growth Stages
Zoea Stage
The female clawless verm crab will carry the eggs on her abdomen for a two-week period before releasing them into the ocean waters.Megalopa Stage
Almost like plankton, the crab larvae will live in the open waters and grow rapidly through a series of molts over the course of a weekImmature Stage
At the end of the larva stage, it will molt into an immature crab, return to land, and begin to grow even further. In this stage, the males and females are indistinguishable.Mature Stage
The immature crab will continue to molt when it is on land, growing larger in size aver the course of three weeks. The females will stop at around 1-1.5 inches while the males will continue to grow until they are about 2 inches. In this stage, they are far more distinguishable based on the size of their umbrella shells, which is wider on the males. Then, the males will mate with the females and the cycle starts all over again!
Lifespan
2-3 years
Average Weight
.06-.10 ounces (1.8-2.8 grams)
Average Length
1 to 2 inches (2.5 to 5 cm)
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