paratomy

Paratomy refers to a phenomenon observed in certain organisms where a body part, typically a limb, is incompletely separated from the parent organism during reproduction or regeneration. Instead of a clean detachment, the new individual or regenerated part remains partially attached, creating a partially duplicated or connected structure. This is distinct from complete autonomy, where a limb or offspring detaches entirely.

This process is often observed in some species of annelid worms and other invertebrates during asexual reproduction. When a worm undergoes fragmentation, one or more fragments may begin to regenerate a new body, but the connection to the original worm might persist for a period before eventually breaking. Similarly, in some cases of limb regeneration in certain invertebrates, the regenerating limb might initially remain connected to the body.

The term "paratomy" can also be applied in a broader sense to describe incomplete fission or budding where the resultant individuals or structures are not fully separated. It highlights a stage in a developmental process rather than a final, independent form. The reasons for this incomplete separation can vary, possibly related to resource allocation, timing of developmental signals, or the specific mechanisms of regeneration or reproduction within a species.