# Effects of adult and egg predators on hatching plasticity of the pulmonate limpet

## TL;DR

This study shows that embryos of a marine invertebrate adjust hatching timing in response to egg predators, not adult predators.

## Contribution

It is the first study to investigate adult and egg predator effects on hatching plasticity in marine invertebrates under natural conditions.

## Key findings

- Adult predators before and after egg-laying did not affect hatching timing.
- Egg predators after egg-laying accelerated hatching timing.
- Embryos, not parents, regulate hatching timing in response to predation risk.

## Abstract

In response to predation threats during the embryonic period, prey from diverse taxonomic groups exhibit plasticity in their hatching timing. In theory, predators of adult prey, as well as predators of eggs or embryos, can influence hatching timing. Similarly, not only embryos but also parents of prey can regulate hatching timing. However, research on the influence of adult predators and adult prey on hatching timing in species with separate predators for adults and eggs remains limited. To the best of our knowledge, no study has investigated this phenomenon in marine invertebrates under natural conditions. In this study, we investigated the effects of life-stage-specific predators (i.e., adult and egg predators) on the hatching timing of the pulmonate limpet (Siphonaria sirius), which undergoes planktonic development on an intertidal rocky shore. The presence of adult predators before and after egg-laying did not affect the hatching timing. Furthermore, while the egg predators present before egg-laying did not influence hatching timing, those present after egg-laying accelerated it. The results indicate that embryos, rather than their parents, determine hatching timing in response to their own predation risk. This finding highlights a strategy in which organisms with planktonic development rely on embryonic plasticity to mitigate strong predation risks during the egg stage. To understand how predation risk shapes predator–prey dynamics, it is critical to identify how predators, specific to each life-history stage of prey (such as adult and egg), interact with prey at different life-history stages during key events like reproduction.

The online version contains supplementary material available at 10.1007/s00442-025-05712-5.