The Caribbean Reef Squid is a small (20 cm) torpedo-shaped squid with fins that extend nearly the entire length of the body and undulate rapidly as it swims.
You can encounter them mostly in schools of 4 to 30 in shallow waters.
They communicate using a variety of color, shape and texture changes. Squid are capable of rapid changes in skin color and pattern through nervous control of chromatophores. Caribbean Reef Squid can send one message via color patterns to a squid on their right, while they send another message to a squid on their left.
I've filmed these squids during a shore dive at Cobalt Coast, Grand Cayman. No lights were used, only ambient light, no filters, no color correction in editing, a 60mm macro lens on a Canon 7D and manual focus.