Date: 1970
Purpose: To explore the unique ecosystem of Clipperton Island, focusing on its dense population of Clipperton crabs and their intriguing behaviors. The expedition aimed to study the instinctive and group dynamics of these crustaceans and document the natural history of the island.
Expedition Overview
In 1970, the crew of the Calypso ventured to Clipperton Island, a remote atoll in the Pacific Ocean located approximately 1,000 km off the coast of Mexico. This tiny, isolated French territory is home to a remarkable ecological phenomenon: an overwhelming population of Clipperton crabs.
Described by Jacques Delcoutère as the island’s true owners, these crabs—each measuring just 4 to 6 cm—dominate the ecosystem. Though small, their sheer numbers and bold, opportunistic behavior make them a fascinating yet formidable presence. The Calypso team spent several days observing these crustaceans, documenting their voracious feeding habits and exploring the mysteries of their instinctive behaviors.
Key Locations & Activities
Observation of Crab Swarming Behavior
- Experiment: Jacques Delcoutère, dressed in a dive suit, lay motionless on the beach to observe the crabs’ reaction to an unfamiliar stimulus.
- Findings:
- A single crab quickly climbed onto him, prompting others to follow. Within minutes, the beach’s entire population of crabs swarmed over his prone body.
- The crabs exhibited coordinated group behavior, suggesting they might emit signals—auditory, olfactory, or otherwise—that prompt others to converge.
Crab Feeding Habits
- Observation: The Clipperton crabs, constantly scurrying across the island, appeared to eat indiscriminately. Anything encountered was potential food.
- Significance: This voracious feeding behavior underscores the crabs’ role as key players in Clipperton’s ecosystem, shaping its unique environment.
Notable Contributions
Behavioral Insights
- The expedition provided a rare glimpse into the instinct-driven behaviors of Clipperton crabs. Their rapid, swarm-like reaction to Delcoutère’s experiment hinted at sophisticated communication or signaling mechanisms among the crustaceans.
Ecological Documentation
- By documenting the overwhelming dominance of the crabs, the Calypso team highlighted the island’s unusual ecological balance, where these crustaceans are a defining feature of the environment.
Human Interaction with Wildlife
- Delcoutère’s account of being swarmed by dozens of crabs offered a vivid, firsthand perspective on the unnerving and unpredictable interactions between humans and wildlife in remote ecosystems.
Challenges Encountered
Close Encounters with Crabs
- Delcoutère described the experience of being swarmed as “terrifying,” noting the sensation of being climbed on, pinched, and tested for edibility by the relentless crustaceans.
Remote Location
- Clipperton’s isolation posed logistical challenges, requiring the Calypso crew to be entirely self-sufficient during their extended stay on the island.
Conclusion
The 1970 Clipperton expedition captured the extraordinary natural history of this remote atoll and its dominant crab population. By studying their behaviors, the Calypso team deepened our understanding of instinctive and group dynamics in crustaceans. While the crabs’ voracity and swarming tendencies left a lasting impression on the crew, the mission emphasized the importance of preserving such unique and delicate ecosystems.
