For the first time, the arm movements of octopuses in diverse natural environments have been analyzed, revealing surprising patterns of role division and extraordinary motor flexibility.
Octopuses are among the most neurologically complex invertebrates, and are renowned for their extraordinary agility. Their eight arms allow them to hunt hidden prey, communicate, explore, and even mate in a variety of underwater environments. Although octopus arms are considered one of the most flexible systems in nature, their full range of motion has rarely been studied—especially in the wild.
A new study by Florida Atlantic University (FAU) in collaboration with researchers from the Marine Biological Laboratory in Woods Hole, Massachusetts, has analyzed for the first time the utility of octopus tentacles in diverse natural contexts. The study, published this week in Scientific Reports, examined how tentacle movements relate to the animal's overall behavior in complex natural environments.
Surprising patterns of role division
The study documents for the first time how octopus arm movements communicate with entire behavior in complex natural environments. Credit: Chelsea Bentis, Florida Atlantic University, and Roger Hanlon, Woods Hole Marine Biological Laboratory.
The findings show that each arm is capable of performing all types of actions, but there is a clear division: the front arms are used primarily for exploration, while the rear arms mainly assist with movement.
In addition, the octopuses showed extraordinary flexibility – one arm could perform several movements simultaneously, and different movements were coordinated between different arms, indicating complex motor control.
Chelsea Bentis, a research associate at FAU's Marine Laboratory and the lead researcher, explained:
"In the wild, we have seen octopuses use different combinations of arm actions – sometimes just one arm to grab prey, and sometimes several arms together to crawl or perform a 'parachute' attack, a unique hunting technique."
Broad methodology
The researchers analyzed nearly 4,000 arm movements from 25 video recordings of three octopus species observed in six different shallow-water habitats—five in the Caribbean and one in Spain. They identified 12 different arm actions across 15 behaviors, including shortening, extending, bending, and twisting.
During the observations, approximately 7,000 arm deformations were recorded. All four types of movements occurred in all arms, but functional specialization by region was evident: flexions occurred mainly at the ends of the arms, while extensions occurred mainly close to the body.
Dr. Roger Hanlon, a senior scientist at the Woods Hole Naval Laboratory, said:
"I believe that you need to enter the natural world of the animal you are studying, and especially its sensory world. Fieldwork is very difficult, and it also takes quite a bit of luck to capture true natural behaviors."
The importance of evolution and applications
The habitats studied ranged from smooth sandy bottoms to complex coral reefs. The octopuses used their tentacles not only for feeding and locomotion, but also for advanced camouflage against predators – for example, imitating moving rocks or floating algae. They also built burrows, repelled predators, and even fought with rivals during mating.
"Understanding these natural behaviors not only deepens our knowledge of octopus biology," says Bentis, "but also opens up new research directions in fields such as neuroscience, animal behavior, and even soft robotics inspired by these amazing creatures."
The study also included Kendra Borsch, Jennifer Grossman and Tila Morano of the Woods Hole Marine Laboratory. The research was supported by the Shulley Foundation, the Ben-Venist Family Foundation and the U.S. Office of Naval Research.
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