IDENTIFICATION
The mud crab is the largest marine or estuarine crab found in KwaZulu-Natal and is a member of the swimming crab family. The carapace is oval with nine pairs of equal-sized marginal teeth. The nippers are substantially larger in males than in females. They are green-brown in colour with the limbs having a net-like pattern especially on the paddle-shaped last pair. The mud crab can reach a size of 30 cm carapace length.

DISTRIBUTION
Mud crabs are found in open, large estuaries with a muddy substrate. They occur from Knysna northwards along the east coast and in many tropical parts of the world. In KwaZulu-Natal, they are found in most of our estuaries. Mud crabs live in burrows which extend into the ground at an angle of approximately 30 degrees. Burrows extend below the low water mark and always contain some water. Burrows appear to be permanent structures used by successive generations.

FEEDING
Despite the formidable size of its nippers, the mud crab feeds mostly on small prey such as tiny snails. However, it is also an opportunistic feeder and will eat dead fish or other animal matter.

REPRODUCTION
Like most estuarine animals, mud crabs spawn at sea. The females migrate out to sea while the males remain in estuaries. Mating and spawning takes place throughout the year but there are definite summer peaks. Mating takes place in estuaries. A male can only inseminate a female while her shell is soft during a period of about 48 hours following her moult. The male straddles the female and will actively defend her against intruders. This situation is maintained until the female moults and then sperm transfer takes place. Sperm is transferred to the females