Autotomy is the ability of an animal to sever an appendage. Autotomy occurs as a means of self-defense. Geckos and lizards, some molluscs and spiders exhibit autotomy.

a process called autotomy common to Gecko's

This process clearly does not result in new organisms and hence not reproduction. Which clearly says that autotomy is not considered reproduction. In some cases, autotomy is not considered as a type of reproduction. It is also not classified as reproduction because this process does not result in new organisms such as new lizards and stuff. Like regeneration. Regeneration is considered as reproduction because reproduction result in formation of new species.

a process called autotomy common to Gecko's

some defeneses against crabs would be camoflouge, hide away, and limb autotomy