The picture in this article shows what a pond looks like when crawfish molting is taking place. An oily film floats at the top of the water and starts to become more visible as the wind pushes it together at the edges of the fields.

Crawfish must shed their skin or molt periodically to grow. As the crawfish grows it fills its hard shell with tissue. Once filled, a new soft skin forms beneath the hard shell in preparation for molting. When molting, the hard outer shell is discarded and the emerging soft crawfish can increase in size.

The bad news is that crawfish, when molting and caught in the trap, are difficult to keep alive. But the good news is that they are growing. Crawfish will molt 12 – 13 times a year, typically during the warmer months of the year, usually in the spring and summer. Environmental factors such as temperature, water quality and food availability trigger the molting process.

When crawfish molt, they shed their exoskeleton, which is their hard outer shell. During molting, the crawfish’s old shell splits open and the crawfish emerges soft and vulnerable. This process can last a few hours or even a few days. During molting, the crawfish may appear lifeless, lying on its side or back, with its legs and claws limp. The molt will dramatically change the color of crawfish from a camouflage olive/brown, to a bright orange or red cast, making them an easy visual target for bass, even though bass must work more diligently, and expend much more energy to catch a crawfish during the molt than during the mating cycle.

As they are molting, they pump water into their body and stretch out their skin like a water balloon. Slowly hormones are released, and the skin begins to harden. During this time, the animal hides away in a crevice, cave, or under a rock so that they are less likely to be attacked and eaten by another crustacean or fish.

After molting, the crawfish’s new exoskeleton is soft and takes a few days to harden. During this time, the crawfish is at greater risk of being a predititor to another crustacean or fish. Molting allows the crawfish to grow larger and replace damaged or work-out exoskeletons.