Understanding the Reasons Behind Slow Movement in Spiders

Researchers from Universitas Indonesia and the Leibniz Institute for Zoo and Wildlife Research in Germany identified energy conservation as the primary reason slow lorises move at speeds averaging 0.17 meters per second, according to a study published in the journal Biology Letters. The findings, based on 200 hours of video analysis and metabolic rate measurements, challenge earlier hypotheses linking their slow movement to predator avoidance or social behavior.

The study tracked 15 slow lorises across Sumatra and Borneo between 2021 and 2023, using GPS collars and thermal imaging to monitor energy expenditure. Lead researcher Dr. Rina Wijaya, a primatologist at Universitas Indonesia, stated the team observed that lorises reduced movement during periods of low food availability, aligning with the theory that their pace conserves energy. “This is a strategic adaptation to survive in environments where resources are unpredictable,” Wijaya said in a press release.

Metabolic data revealed slow lorises burn 40% less energy per kilogram than similarly sized primates, according to the study. Researchers attributed this to a combination of low muscle mass and a unique jaw structure that allows them to consume toxic prey, such as millipedes, without harm. The study also noted that lorises secrete a toxin from glands on their elbows, a defense mechanism that may reduce the need for rapid escape responses.

Conservation groups have emphasized the findings’ relevance to protecting the species, which is classified as vulnerable by the IUCN. “Understanding their energy constraints informs better habitat management,” said Dr. Andi Surya, a wildlife biologist with the Indonesian Biodiversity Foundation. The study’s authors recommended expanding research to compare slow loris movement patterns with other slow-moving mammals, such as pangolins and sloths.

The research team plans to publish a follow-up analysis in 2024 examining how climate change might affect food availability for slow lorises. The study’s data is also being shared with the Wildlife Conservation Society, which is developing guidelines for preserving primate habitats in Southeast Asia.