C. elegans feed yolk to their young in a form of primitive lactation

Here it is shown that post-reproductive mothers vent yolk which can be consumed by larvae and promotes their growth. This implies that later yolk production is not futile; instead vented yolk functions similarly to milk.

Yolk venting is promoted by insulin/IGF-1 signalling (IIS). These findings suggest that a self-destructive, lactation-like process affects resource transfer from post-reproductive C. elegans mothers to offspring, in a fashion reminiscent of semelparous organisms that reproduce in a single, suicidal burst. That this process is promoted by IIS provides insights into how and why IIS shortens lifespan in C. elegans.

https://doi.org/10.1038/s41467-021-25821-y