Shrimp do not live very long (the oldest shrimp only become five years old) and they must, therefore, grow quickly. Growing, however, is a very big problem. Just as crabs and crayfish, shrimp do not have bones but their skeleton can be found on the outside. At a given moment this armour becomes too small and then the time has arrived to moult. Before shrimp can moult, it is important that they have eaten enough because during the moulting process they cannot eat. Moulting usually takes about five days. To moult, shrimp will first drink a lot of water. This will make them swell up. A new shell will now grow underneath the old shell. This new shell will also absorb many substances from the old shell. When the new shell is ready, the shrimp will crawl out of its old shell (you can quite often find these old shells on the beach). Shrimp will still be very vulnerable at this stage because the new shell is not hard yet (this will take another day or two). Shrimp, of course, cannot defend themselves properly with such a weak shell (which also means that their claws are weak). When the shell has finally hardened, shrimp will have grown by about 10%. In the first year, shrimp will moult 25 to 30 times. The older they become, the less they grow and the less often they moult. A male shrimp can become at least 6 centimetres and a female shrimp nearly 9 centimetres.
