Interactions Between Molting and Regeneration in the Land Crab

Following the loss of one or more primary regenerates from the land crab, Gecarcinus lateralis, before a critical stage of the molt cycle (probably D1, early), secondary regenerates form to replace those lost.2. Although loss of at least five limbs from an intermolt animal is required to initiate molting preparations (Skinner and Graham, 1972) loss of only one primary regenerate, prior to the critical time, is sufficient to inhibit these preparations.3. Following the loss of one or more primary regenerates before a critical time, the rate of growth and the synthesis of DNA in other primary regenerates that remain in situ decrease or cease temporarily (10 to 14 days).4. The precise stage of the animal in the molt cycle determines whether growth and/or DNA synthesis decrease or cease in the remaining primary regenerates. Loss of regenerates early in D0 (R = 7-10) causes a decrease; loss of regenerates later in D0 or early D1 (R = 10-17) causes complete inhibition.5. The duration of the premolt period is lengthened by the same time as that during which the early stages of re-regeneration of the missing regenerates occur. 6. Primary regenerates removed after the critical point in the premolt period are not re-regenerated before ecdysis; the premolt period is not extended and the animal emerges without a full complement of limbs.7. Primary regenerates in animals without eyestalks respond similarly to those in animals with eyestalks. This excludes the possibility that the inhibition is caused by release of MIH from the sinus gland-X organ complex. Other physiological factors must be posulated.