Maybe it has to do with the sudden one-piece removal of your whole outer body...for mantis shrimp, they have to worry about: 1. Squeezing out of all the nooks and crannies such as out of their rapts, telsons etc. 2. Ecdysis (preparation for the molt) takes up valuable resources and energy 3. They have to prepare for around a week or two (depending on size) of fasting. I recall Dr. Caldwell saying it is a high energy-taking process. 4. Once they are done, they are all soft and are at risk of being eaten. Adding to this is the problem that they cannot use their rapts until their shells have hardened. 5. Other mantis shrimp. They are often stressed out with the worry that another mantis shrimp will come into their territory during this time. 6. Not sure why but they become a lot more susceptible to changes in water chemistry.