If you spot a pen shell or giant cockle shell in the shallows, open it! Why? If you’re lucky, you might find a crab or an octopus inside. We most commonly find the Atlantic pygmy octopus on our beaches, and they love to hide inside shells and rocks. 

Pygmy octopus habitat extends throughout the waters surrounding Florida, across the Gulf of Mexico, and to parts of the Caribbean, where they live in empty shells, crevices, or holes in reefs. They are solitary creatures, although they do form intraspecies social hierarchies based on their size — the larger individuals have access to better food (mostly crabs and snails) and habitat. Like most octopus species, they are adept at camouflage, blending in with the surrounding rocks by changing their color. Once threatened, their primary form of self defense involves distracting and blinding their predators with ink.

As indicated by the word pygmy, these octopi are quite small. Their body only reaches a maximum length of about 15 cm. They have eight arms, a mantle (body), and no bones or hard parts except for a hard beak made of chitin. Without any rigid internal structure, octopuses can squeeze through small holes and contort themselves to fit in any space. And their less visible anatomical structures can seem equally alien to us humans. For example: control of their nervous system is not located solely in the head. Instead, the arms possess a degree of autonomy for the coordination of movement! And in place of one multi-chambered heart, two branchial hearts pump blood across the gills, while a third heart distributes blood through the rest of the body!

Octopuses are a fascinating group of organisms. They are intelligent, psychologically and physiologically unique, and far from being fully understood. And fortunately for us, some of them live right near Sanibel. Best of luck searching for a pygmy octopus – we hope you will share a photo with us if you find one!
 

References/ More Information:
http://animaldiversity.org/accounts/Octopus_joubini/
https://en.wikipedia.org/wiki/Octopus#Biology