Encounters with a polka-dotted octopus in the Turks & Caicos Islands.

By Emily Lekas ~ Edited by Dr. C.E. O’Brien ~ Photos by Dr. C. E. O’Brien & Center for Marine Resource Studies Students & Staff

Dots have pleased the human eye for centuries, inspiring a sense of whimsy. Today, they adorn everything from bow ties to wrapping paper to Minnie Mouse. Thus, it is no surprise that students at the School for Field Studies (SFS) in South Caicos smile with delight when the sand octopus (Callistoctopus furvus), startled by their arrival, suddenly changes its appearance from a nondescript mottled pattern that blends into the background to one displaying large white polka dots across a brick red body. Amusement, however, is not the response the octopus desires. Instead, the dots’ stark contrast is meant to startle and intimidate potential predators. This charming bravado has earned this species a nickname: “polka-dotopus.”

Octopuses are marine invertebrates found in every ocean in the world—even the Arctic! There are an estimated 300 known species which range in size from just over two centimeters to nearly five meters in length and eat a diet of molluscs, crustaceans, and fish. They live in a variety of habitats including coral reefs, seagrass meadows, and the open ocean and are famous for their extraordinary camouflage abilities which enable them to blend into these environments.

Changes in an octopus’ skin color, reflectance, and texture are made possible by chromatophores (pigment-filled cells in the skin which expand and contract to display or hide their internal colors), iridiphores, leucophores (reflective cells), and papillae (flexible patches of skin that can be smooth or pucker into a bump). In the shallow waters of the Turks & Caicos Islands, complex patterns of colors and textures allow the polka-dotopus to stealthily pursue its prey and hide from predators like eels, sharks, and rays. 

This Callistoctopus furvus (a.k.a. Polka-dotopus) is displaying the Polka Dotted skin pattern and Deimatic Arm Spread posture as it travels along the sandy bottom in South Caicos.

The polka-dotopus is just one of at least eight species of octopuses that inhabit the coastal waters surrounding the Turks & Caicos Islands. Dr. C.E. O’Brien, Associate Professor of Marine Ecology at the School for Field Studies Center for Marine Resource Studies (CMRS) on South Caicos, specializes in the study of three intriguing species: the Brazilian reef octopus (Octopus insularis), the Caribbean reef octopus (Octopus briareus), and the sand octopus (or polka-dotopus, Callistoctopus furvus). Students working with Dr. O’Brien assist in field data collection via snorkel and SCUBA diving, analyze videos and prey remains in the laboratory, and test hypotheses about octopus skin patterning and behavior.

The Caribbean reef octopus and the polka-dotopus are nocturnal, so the student scientists (nicknamed “NOcto-Squad”) SCUBA dive and snorkel at night with lights and cameras to find and film them. Over the course of four years (2021–2024), NOcto-Squad has captured several hours of footage of both species. These videos were filmed with either white light to document the full range of skin patterns or red light to observe their behavior in a less intrusive manner, as red light is thought to be less visible to octopuses. Students analyzed these videos second-by-second, creating a dataset of skin pattern, behavior, posture, texture, and substrate. Each cohort of the NOcto-Squad has used these data to test hypotheses, write a research paper, and present its findings to the CMRS and greater South Caicos community.

I was a member of NOcto-Squad during my semester at the CMRS in the spring of 2023. My squad-mates Tessa Weir, Gwen Gisler, L.A. Atkins, Saige Ferguson, Hayden Lawton, and I SCUBA dived in shallow reefs and seagrass beds filming the polka-dotopus and the Caribbean reef octopus. During these long, shallow dives we observed the exotic marine night life of South Caicos. We witnessed a fight between an octopus and an eel, strange nocturnal creatures like slipper lobsters, sea cucumbers, and cowrie snails, and normally-active fish asleep on the seafloor. After concluding our research project, we presented our findings to our cohort and students at Marjorie Basden High School. 

Upon returning to my home university in Richmond, Virginia, I continued working with Dr. O’Brien, analyzing videos of the polka-dotopus to create an ethogram of this species. Ethograms are formal, descriptive catalogs of a species’ behavior and aid in the accurate identification and study of the organism. An octopus’ behavior includes its skin patterns, postures, textures, and movements. We cataloged and described every skin pattern, posture, texture, and behavior exhibited by the polka-dotopus in each second of our videos, as well as in online media gathered from YouTube, Facebook, iNaturalist, and other octopus scientists.

The polka-dotopus uses two colors, red and white, to create six kinds of skin patterns (Brick Red, Racing Stripe, Mostly White, Mottle, Stippled, and Polka Dotted) that are further divided into 16 sub-patterns. Polka-dotopuses can also produce three distinct skin textures using their large, U-shaped papillae: Smooth, Papillate (a very bumpy texture), and Coarse (an intermediate). In combination with 10 different body postures, including ones that resemble flowers, torpedoes, gnomes, and parachutes, the polka-dotopus can take on a variety of distinct appearances to remain hidden from potential prey and to deter detection, recognition, and attack by predators.

One of the distinguishing features of the polka-dotopus is its polka-dotted display in response to a threat. Octopuses often respond to threats by puffing up their bodies, spreading their arms wide, and creating a contrasting skin pattern in order to increase their apparent size to intimidate or startle a predator. This is known as a deimatic display and is a common defense across many species of octopus. However, the polka-dotopus may be unique among octopuses in its use of the namesake pattern. Another interesting pattern we observed in this species was dubbed “racing stripe” for the thick white stripe produced down the center of an otherwise brick red body, resembling the paint job on a race car. The purpose of this pattern is not entirely clear, but it may “break up” the outline of the body, helping the octopus pretend to not be an octopus. 

Select behaviors of the “Polka-dotopus” include (from left): Parachute Attack, Bipedal Locomotion, and Jetting.

We also observed 11 different behaviors in the octopus ranging from the mundane (crawling, arm exploration, stationary) to the exotic (parachute attack, bipedal locomotion). During “Parachute Attack,” the octopus extends its arm web (the skin between its arms) and pounces to engulf an area of rock or sand and capture a crab or other prey trapped underneath. However, we did not frequently observe this behavior, suggesting that the polka-dotopus likely catches most of its prey by feeling in the crevices of the sea floor for tasty morsels. 

Another interesting behavior exhibited by C. furvus is “Bipedal Locomotion,” in which the octopus “walks” across the seafloor on its back two arms while raising its front two arms up in a corkscrew shape. (See Times of the Islands Winter 2025/26 “Green Pages.”) This behavior, often combined with a bumpy texture and dark red coloration, appears to be the octopus’ attempt to masquerade as a handful of algae floating by. Additionally, the polka-dotopus may be able to mimic a trumpetfish or cornetfish by assuming a torpedo posture and slowly jetting away in a long, slender shape.

These amazing behaviors are just the beginning of what we have to learn about the polka-dotopus. In such a biodiverse and dynamic environment as the tropical Atlantic, it is likely that there are other fascinating behaviors that have never been seen before.

Our ethogram increases our understanding of life underwater in the Turks & Caicos Islands and will facilitate further study of the polka-dotopus. Every new observation and study of animal behavior expands our knowledge of the sophistication and complexity of marine animals’ interactions with their environment.

This is particularly true when studying octopuses, as these spineless sea creatures have demonstrated remarkable abilities including recalling long-term memories, executing clever defensive and predatory strategies, and even solving puzzles. Dr. O’Brien’s team is now investigating the relationships between skin patterning, behavior, and substrate in the polka-dotopus, uncovering information about how octopuses make decisions and survive in complex environments. 

Our work also highlights the amazing biodiversity of our “Beautiful by Nature” Islands. From coral reefs to seagrass meadows to mangrove roots, TCI’s marine ecosystems have much to teach us. Every organism from the smallest sand dollar to the massive humpback whale plays a unique ecological role and contributes to the overall health of this region. With continued respect and protection for our waters, residents and visitors to the Turks & Caicos Islands can enjoy this captivating biodiversity for generations to come.