The Reef Squid (Sepioteuthis sepioidea) is one of the most charismatic creatures you’ll meet underwater. With their sleek bodies, pulsating colors, and curious behavior, they’re like underwater UFOs—darting around with jet propulsion and flashing signals like disco lights. If the image looks a little bit blurry, please accept our pardons—those things are fast!
Fun Fact First:
Reef Squid can change color and texture instantly, thanks to specialized skin cells called chromatophores. They use this ability not just for camouflage, but for communication. It’s like having a built-in LED display that broadcasts mood, intent, and even mating readiness.
Each chromatophore is a tiny sack of pigment surrounded by muscles that contract and expand to reveal or conceal different colors. What makes reef squid chromatophores especially fascinating is their neurological control. Unlike many animals that rely on hormonal changes for color shifts, squid chromatophores are directly wired to their brains, allowing for lightning-fast responses. This means a reef squid can change its appearance in milliseconds—flashing stripes, spots, or even pulsing waves of color across its body. During mating rituals, males often display vibrant patterns to attract females, while rival males may use color to assert dominance. Scientists study squid chromatophores to better understand neural control, pattern generation, and even applications in dynamic camouflage technology.
The squid in this photograph was part of a group of three that hovered in front of our divers on a recent shore dive. They zipped around like hummingbirds and were constantly flashing colors at their reflection in the camera’s dome port.
Where to Find Them
You’ll spot Reef Squid in shallow coastal waters, especially near coral heads, seagrass beds, and mangrove roots. They’re common in the Florida Keys and along the reefs of Broward and Miami-Dade counties.
They often travel in small groups and hover in place, watching divers with what feels like genuine curiosity. We don’t see them regularly in Fort Lauderdale, but they are there. You also have to be looking up to find them, as they like to swim higher in the water column.
Habits and Behavior
Reef Squid are social and intelligent. They use jet propulsion to move, squirting water through a siphon to zip around with impressive agility. They’re also known for their synchronized swimming and coordinated hunting.
During mating season, males perform elaborate displays, flashing colors and patterns to attract females. Once paired, they mate head-to-head in a surprisingly tender exchange.
What They Eat (and Who Eats Them)
Reef Squid are carnivores, feeding on small fish, shrimp, and other crustaceans. They use their tentacles to snatch prey and their beak to tear it apart.
Predators include larger fish like groupers and jacks, as well as dolphins and even other squid. Their best defense is speed, camouflage, and a quick squirt of ink to confuse attackers.
Why They’re Interesting
Reef Squid have some of the most advanced eyes in the animal kingdom. They can detect polarized light and have excellent contrast vision, which helps them hunt and communicate. Scientists study them to understand neural processing and visual systems.
Content created by Gen AI but edited by scuba divers for scuba divers. Photography courtesy of Christopher Duncan, copyright 2025 CDA Underwater Photography, all rights reserved worldwide.