All Cephalopods have chromatophores, special pigmented and light reflecting cells on their skin which allows them to change colour and texture quickly.

[4] Much of the information about O. joubini was obtained through laboratory studies of captive specimens and what little is known about their behavior in a natural environment is inferential.

[4] Though research is limited, some studies suggest that O. joubini have a complex system of sensory cells along their lip that serve a chemotactic function.

[4][6] Many laboratory experiments have shown that O. joubini prefer to remain hidden or, in the case of a tank environment, close to the sides of the enclosure.

[4] The key characteristics that differentiate O. joubini from O. mercatoris, and other unidentified pygmy octopuses, is the size of the eggs and its color.

[4] Females of this species breed between March and June, laying elliptical, amber eggs in a sheltered place.

By the third week, O. joubini undergo intense feeding and rapid growth, sometimes tripling in weight, and transition from the planktonic stage, becoming fully benthic.

It uses its radula, a small, spikey, tongue like structure, to drill a hole in the prey's shell, and proceeds to secrete poisonous saliva out of its beak to paralyze its victim.

[4] Though octopuses are solitary animals, they do appear to partake in various social interactions, especially when living in high densities or in limited space (as in a laboratory environment).

In 1999, a harmful algal bloom wiped out an entire population of Octopus mercatoris in St Joseph's Bay, Florida.