Giant Humboldt squid, which can grow as big as a man, speak to each other in flashes of color, their whole bodies quickly changing from red to white and back again. But just what they’re communicating has long been a mystery to scientists.

Now, new video analysis is allowing marine biologists to begin cracking this jumbo squid’s code.

The new research is the first to track communications between free-swimming Humboldt squid, partly because the animals show no fear of human divers. They’ve been known to rip off a diver’s mask and to attack lighting and camera equipment. The predators sport suckers lined with sharp teeth, have a two-inch-long beak used to sever the spines of fish, and have no qualms