What Octopuses Eat When They Settle Down: Insights from DNA Analysis

Greg Howard
25th July, 2024

What Octopuses Eat When They Settle Down: Insights from DNA Analysis

Recently settled common octopus (Octopus vulgaris) (b), collected from the NW Mediterranean sampling area (a), were identified as specialized predators whose diet consists mainly of amphipods.

Image adapted from: Escolar et al. / CC BY (Source)

Key Findings

  • The study focused on the diet of recently settled Octopus vulgaris in the Mediterranean
  • Amphipods were the primary prey, found in all analyzed stomach contents
  • As octopuses grow, their diet diversifies to include hydrozoans, decapod crustaceans, cephalopods, and bivalves
Understanding the dietary habits and ecological roles of marine creatures is crucial for maintaining healthy ecosystems. The settlement phase, when meropelagic octopuses transition from a planktonic existence to life on the sea bottom, presents a particularly challenging period. To shed light on this critical life stage, researchers from the Institut de Ciències del Mar (ICM-CSIC) conducted a study on the diet of recently settled Octopus vulgaris in the Mediterranean, using molecular methods to analyze stomach contents[1]. The study found that amphipods, small crustaceans commonly found in marine environments, were present in all the analyzed stomach contents, with 20 amphipod taxa identified as prey. The most commonly found species were Jassa slatteryi and Microprotopus maculatus. Other important prey included hydrozoans, decapod crustaceans, cephalopods, and bivalves. This indicates that recently settled octopuses are specialized predators, focusing primarily on amphipods. However, as they grow, their diet diversifies, suggesting a shift from specialization to a broader range of prey. This ontogenetic shift in diet is significant. The considerable elongation and strong muscular development of the octopus's arms after settlement likely enable them to develop ambush predation and speculative hunting strategies. This adaptation increases the range of potential benthic prey species they can target, aiding their survival and growth in their new benthic habitat. The findings of this study align with previous research on the ecological roles and dietary habits of marine organisms. For instance, the use of environmental DNA (eDNA) metabarcoding to assess species distributions and abundances has revealed highly diverse marine communities, with significant variations among locations[2]. This method has proven effective in rapid biomonitoring and inventorying marine biodiversity, highlighting the complex interactions within marine ecosystems. Additionally, research on larval mortality and morphological abnormalities in benthic octopuses has shown that these challenges can significantly impact their survival and development[3]. The ability of octopuses to adapt to challenging morphologies and environmental conditions underscores their resilience and adaptive capacity. Furthermore, studies on the diets of early paralarvae of flying squids have revealed that these cephalopods undergo an ontogenetic shift in diet, transitioning from detritivore suspension feeding to active predation[4]. This unique life strategy allows them to exploit different food resources at various life stages, similar to the dietary shifts observed in Octopus vulgaris. In summary, the recent study by the Institut de Ciències del Mar (ICM-CSIC) provides valuable insights into the dietary habits and ecological roles of recently settled Octopus vulgaris. By examining their stomach contents, the researchers have highlighted the importance of amphipods in their diet and the ontogenetic shift towards a more diverse range of prey as they grow. These findings contribute to our understanding of marine ecosystems and the adaptive strategies of marine organisms, building on previous research in the field.

GeneticsAnimal ScienceMarine Biology

References

Main Study

1) Octopus diet during the settlement period using DNA metabarcoding

Published 24th July, 2024

https://doi.org/10.1007/s11160-024-09875-x

Related Studies

2) Biodiversity assessment of tropical shelf eukaryotic communities via pelagic eDNA metabarcoding.

https://doi.org/10.1002/ece3.5871

3) Potentially handicapped but otherwise functional: Malformations in prey capture tools show no impacts on octopus life.

https://doi.org/10.1002/ece3.6903

4) Predatory flying squids are detritivores during their early planktonic life.

https://doi.org/10.1038/s41598-018-21501-y


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