Mangrove Crabs: Types, main characteristics and importance

This time you don´t need to go to the beach to know everything about the mangrove crabs, which are creatures of beautiful colors that adorn the rocks and sand with their extreme beauty.

Crabs are animals that we find not only on the coast, but also on television and books, because thanks to their beauty and funny walking, they have been the protagonists of commercials, movies, and children’s stories. Now let´s learn about …..

Characteristics of Mangrove Crabs

Mangrove crabs are animals that live on the grounds of a tropical area in the form of islands, or steppes, with trees highly resistant to salt water.

There are many species of such crabs, which moreover are ecologically significant, since they maintain much of the energy within this forest, burying and consuming the garbage from the leaves.

In addition to digging the soil, the mangrove crabs can also climb trees to protect themselves.

These crabs are distinguished by having a relatively narrow oval cephalothorax bent downward, which may be grayish-red or also gray-blue; with its red or orange margins. The ventral area is brown, and its claws are dark in color.

The anterior edge of the shell is occupied by the orbits of the eyes, while the oral cavity is completely covered by the maxillipids, which hide the jaws of the crab. The length of these crabs varies between three and a half, and six centimeters.

Unlike males, females do not have hairy legs, so the prints they leave at the entrance of the burrow are much thinner than those of males. Males are also characterized by having long tongs with sharp tubers. The legs of both sexes are pink in color

Types of Mangrove Crabs

 Fiddler Crab

These crabs are also known as calling crabs, and belong to the family Ocypodidae . They are small crabs of no more than 5 cm across which are distributed along West Africa, the Western Atlantic, the Eastern Pacific and the Indo-Pacific. Fiddler crabs are easily recognizable by their claws clearly asymmetrical

mangrove crabs: fiddler crab

Mud crabs or black crabs (Scylla serrata):

This species is scattered throughout Africa, Australia and Asia. They have the anatomical characteristics listed above. In term of colors, it ranges between green to dark brown.

Let´s watch how they ctach them


This genus is comprised by 23 species of small crabs, most of them scattered throughout the Indio-Pacific Ocean.

mangrove crabs: fiddler crab

Reproduction Method of the Mangrove Crabs

The reproduction of the mangrove crabs depends on the levels of sexual maturity of the males, since they must have sexually mature gonads. The ovulation of the females occurs with a certain delay, with the purpose that they fit before than the gonads. The females can lay a hundred thousand eggs in a single period.

The male transfers his sperm to the female by employing his sexual organs, once they are adapted for fertilization. The females, on the other hand, carry the eggs until they are ready for being released.

During the mating period the female is quite defenseless because her shell is soft in that moment, for this reason, the copulation takes place at night, in the safety of their burrow.

In the same way than most crabs, the mating occurs just after the female has molted her exoskeleton or shell, because that is the time when her body is also more flexible. This process takes place in abandoned burrows, after the male succeeds in subjecting the female, and drag her to that place.

Let´s watch a mud crab molting

What do  the Mangrove Crabs Eat?

This crab is usually an herbivore, or primary consumer, since its main source of food is garbage from mangrove leaves. During the first months of their lives, they feed on polychaetes and microorganisms that they get in the sediments, and the leaves that drag to their burrows. Moreover in certain occasions, dead animals that they find in the mangrove can also make up  their diet

Importance of Mangrove Crabs

Most crabs avoid temperatures above 29 ° C, which indicates that fresh burrows are ideal shelters for them especially during hot days. Therefore, the burrows provide the crabs with protection against particularly high temperatures, desiccation and predators, while maintaining tolerable conditions regarding other essential parameters.

Typically, each crab occupies its own burrow around the mangroves and its roots to protect itself; and covers the openings with mud during periods of high tide. These burrows diminish the effect of extreme temperatures, and serve as water reservoirs, allowing regular immersion to dampen  the gill chambers of the crabs.

Just as the blue crab has its importance, mangrove crabs play an important role in their natural habitat, because they contribute to the secondary production of mangroves. Crab larvae are the main source of food for juvenile fish that inhabit adjacent waterways, so they also collaborate with the coastal fishery.

The burrows of mangrove crabs alter the topography and the size of the sediment grain, which helps to aerate the sediment. If the crab were to disappear from these places, the sulfur and ammonium would concentrate in them; which would affect the productivity and reproductive production of the vegetation.

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