ABSTRACT
The catch connective tissue is defined as the collagenous connective tissue whose mechanical properties can be changed rapidly (in seconds to minutes) under nervous control. This tissue is found in all the supportive systems of echinoderms. When the tissue is in a catch state, the supportive systems become hard and immovable so that they maintain the animal posture and serve as protective “shells”. When it relaxes, the supportive systems become flexible so as to allow deformation and locomotion of the animal. Further softening allows for autotumy (defence) and for fission (reproduction). The echinoderms’ success has very likely depended on the development of catch connective tissues.
