The Mud Crab (Scylla serrata)
Shedding its shell
A crab’s growth consists of a series of moults that happen when it reaches the size of its current shell. Moulting is triggered by hormones. A new ‘cuticle’ (protective layer) is secreted under the old shell. The crab absorbs water, splitting its shell, then backs out of the old shell. Substances stored within the crab’s body are rapidly redeposited to harden the new cuticle into a larger shell. This is an innate behaviour because it is the same for all mud crabs
Mating
Males can only mate with the female whilst her shell is soft, a period of 48 hours after moulting. The male crab can sense when the female is about to moult and pairs up with her. The male climbs on top of the female, clasps her with his legs, and carries her underneath him for up to four days. The male releases the female when she begins to moult and once the female has finished moulting the male turns her upside down to mate. this is an innate behaviour and is the same for all mud crabs and it falls under the reproductive behaviours sub-category.
Burrowing
large individuals prey upon emerged small ones and the number of smaller individuals decreased until total numbers are at the carrylng capacity of burrows in the habitat. Burrows provide protection for the mud crabs from predators such as bigger mud crabs and other species in the area which feed on them. this is a learned behaviour and is a observational behaviour from watching other crabs get eaten if they do not make burrows to hide in so they quickly learn by watching other members of their population.
Why do people study estuaries
Scientists conduct research and monitor activities in estuaries to better understand them and to learn how best to protect them and keep them healthy. Monitoring estuaries allows scientists to observe trends and changes in the ecosystem and to track the health of the estuary and the plants and animals that live there. Research in estuaries allows scientists to learn more about estuaries by making observations and doing experiments.
A crab’s growth consists of a series of moults that happen when it reaches the size of its current shell. Moulting is triggered by hormones. A new ‘cuticle’ (protective layer) is secreted under the old shell. The crab absorbs water, splitting its shell, then backs out of the old shell. Substances stored within the crab’s body are rapidly redeposited to harden the new cuticle into a larger shell. This is an innate behaviour because it is the same for all mud crabs
Mating
Males can only mate with the female whilst her shell is soft, a period of 48 hours after moulting. The male crab can sense when the female is about to moult and pairs up with her. The male climbs on top of the female, clasps her with his legs, and carries her underneath him for up to four days. The male releases the female when she begins to moult and once the female has finished moulting the male turns her upside down to mate. this is an innate behaviour and is the same for all mud crabs and it falls under the reproductive behaviours sub-category.
Burrowing
large individuals prey upon emerged small ones and the number of smaller individuals decreased until total numbers are at the carrylng capacity of burrows in the habitat. Burrows provide protection for the mud crabs from predators such as bigger mud crabs and other species in the area which feed on them. this is a learned behaviour and is a observational behaviour from watching other crabs get eaten if they do not make burrows to hide in so they quickly learn by watching other members of their population.
Why do people study estuaries
Scientists conduct research and monitor activities in estuaries to better understand them and to learn how best to protect them and keep them healthy. Monitoring estuaries allows scientists to observe trends and changes in the ecosystem and to track the health of the estuary and the plants and animals that live there. Research in estuaries allows scientists to learn more about estuaries by making observations and doing experiments.