How do hermit crabs survive when they are buried in sediment?

Hermit crabs, particularly the intertidal hermit crab species *Pagurus samuelis*, can survive being buried in sediment through a process called anaerobic respiration. This allows their cells to produce energy without oxygen. When *Pagurus samuelis* are buried, oxygen diffusion is reduced, and they switch to this alternative metabolic pathway to endure the oxygen deprivation, known as hypoxia.

What did the researchers measure in the hermit crabs' hemolymph, and why?

The study led by Stephen G. Dunbar, Janelle Shives, and Danilo S. Boskovic measured lactate levels in the hemolymph of *Pagurus samuelis* to understand anaerobic respiration. Lactate is a byproduct of glucose breakdown without oxygen, indicating metabolic stress. Higher lactate levels generally correlated with longer burial times, but some crabs survived even with high lactate levels, suggesting a tolerance to its buildup.

Why is it surprising that some hermit crabs survived with high lactate levels?

The fact that some *Pagurus samuelis* survived despite high lactate levels challenges the traditional view that lactate buildup is always toxic. It suggests *Pagurus samuelis* have mechanisms to tolerate or manage the byproducts of anaerobic respiration. This finding opens new research avenues into understanding the limits of hypoxia tolerance in marine invertebrates and the specific adaptations that enable such resilience.

What future research is needed to better understand how hermit crabs survive burial stress and hypoxia?

Future research should focus on the interplay between anaerobic metabolism, glycogen utilization, and other factors influencing the survival of hermit crabs, such as *Pagurus samuelis*, under burial stress. Understanding these adaptations is crucial for predicting how marine organisms might respond to habitat degradation and climate change. Investigating the specific mechanisms that allow *Pagurus samuelis* to tolerate high lactate levels could provide insights into broader strategies for surviving environmental stressors.

Hermit crab emerging from sand, symbolizing survival and resilience.

Buried Alive: How Hermit Crabs Survive Hypoxia

Q: Besides anaerobic respiration, what other factors determine how well a hermit crab survives being buried?

Burial duration is the most significant factor. The shorter the period *Pagurus samuelis* are buried, the better their chances of survival. Factors such as sediment composition, temperature, and the crab's physical condition also play a role. Additionally, the amount of glycogen stores, the energy reserves in *Pagurus samuelis*, can influence their ability to withstand prolonged hypoxia.

Avery Sinclair in Science & Nature August 2025 • 5 min read.

"The secret to hermit crabs' resilience may lie in their anaerobic abilities, challenging what we know about survival under extreme stress."

Hermit crabs, those ubiquitous inhabitants of intertidal zones across the globe, face a daily gauntlet of environmental challenges. From fluctuating salinity levels to the constant threat of predation, their survival depends on a remarkable suite of adaptations. One of the most critical of these adaptations comes into play when they are buried by sediment, a common occurrence in their dynamic coastal habitats. Understanding how these creatures cope with such events is not only fascinating but also provides valuable insights into the broader implications of environmental stress on marine life.

Burial by sediment introduces a complex set of stressors, most notably hypoxia, or oxygen deprivation. As sediment blankets their habitat, the diffusion of oxygen is dramatically reduced, forcing these crabs to rely on alternative metabolic pathways to survive. Scientists have long been intrigued by the physiological mechanisms that allow certain species to withstand these harsh conditions, and recent research is shedding light on the critical role of anaerobic respiration—a process that allows cells to generate energy without oxygen.

New research dives into the anaerobic respiration of the intertidal hermit crab, Pagurus samuelis, when buried in sediment. This study challenges the conventional wisdom regarding the limits of hypoxia tolerance and underscores the importance of understanding the nuanced strategies these animals employ to thrive in challenging environments.

Unearthing the Secrets of Survival

Hermit crab emerging from sand, symbolizing survival and resilience.

The study, conducted by Stephen G. Dunbar, Janelle Shives, and Danilo S. Boskovic, focused on the intertidal hermit crab Pagurus samuelis, a common species found along the California coast. The researchers subjected these crabs to varying periods of burial, mimicking natural sedimentation events. They then measured lactate levels in the crabs' hemolymph (the crustacean equivalent of blood) as an indicator of anaerobic respiration. Lactate is produced when cells break down glucose without oxygen, making it a key marker of metabolic stress.

The findings revealed several surprising insights. As expected, lactate levels generally increased with the duration of burial, indicating a shift towards anaerobic metabolism as oxygen became scarce. However, the relationship between lactate levels and survival was far from straightforward. Some crabs exhibited remarkably high lactate levels yet remained alive, challenging the assumption that lactate buildup is inherently toxic. This suggests that Pagurus samuelis possesses a sophisticated capacity to tolerate and potentially manage the byproducts of anaerobic respiration.

Key findings include:

Lactate levels increased with burial duration, but high levels didn't always mean death.
Crabs found alive at excavation showed varied lactate concentrations.
Burial duration was the most significant factor affecting survival.

Further analysis revealed that burial duration was the most critical factor influencing survival. The shorter the burial, the more likely the crabs were to survive. This highlights the importance of factors such as sediment composition, temperature, and the crab's physical condition in determining its ability to withstand burial. The study also pointed to the potential role of glycogen stores, the crustacean equivalent of energy reserves, in supporting anaerobic metabolism. Crabs with larger glycogen reserves may be better equipped to endure prolonged periods of hypoxia.

Implications and Future Directions

This research underscores the remarkable resilience of hermit crabs and highlights the importance of understanding the complex physiological mechanisms that allow them to thrive in challenging environments. By challenging traditional assumptions about the toxicity of lactate and emphasizing the role of factors such as glycogen stores and pre-conditioning, the study opens new avenues for research into the limits of hypoxia tolerance in marine invertebrates. Future studies are needed to fully characterize the interplay between anaerobic metabolism, glycogen utilization, and other factors in determining the survival of hermit crabs under burial stress. Further research into these adaptations can provide critical insights into how marine organisms might respond to the growing threat of habitat degradation and climate change.