There is a peculiar creature that roams the sunless depths of the ocean. With its deep red colour, icy blue eyes, and webbed tentacles that resemble a cape, the vampire squid appears quite frightening. Illuminated by its bioluminescent glow against the inky darkness of the deep sea, it’s easy to see how this creature gained the scientific name, Vampyroteuthis infernalis, literally meaning “vampire squid of Hell”!

This glowing secretion is the vampire squid’s alternative to the ink used by its shallow relatives to ward off predators. In the pitch black of the mesopelagic zone where this squid resides, 3,000 feet below the surface, black ink simply would not be effective. Instead, the twinkling bioluminescence confuses predators, allowing the vampire squid to slip away unharmed.

However, this demonstrates just one of many fine-tuned adaptations that this cephalopod possesses. For example, it has the largest eyes of any animal on Earth, proportional to its body size. A very useful tool, allowing the squid to absorb as much light as possible.

But the mesopelagic zone of the ocean is not only dark, but resides within the oxygen minimum layer. Here, there may be less than 5 percent oxygen saturation and little or no light. But while most cephalopods cannot survive below 50% oxygen saturation, the vampire squid has found ways of adapting to these conditions, with a slowed metabolism that causes it to require very little oxygen to survive. When feeding, it rarely actively swims, but prefers to drift on ocean currents. By using this efficient method, the squid uses very little energy, which it saves up for times when it faces danger. In such instances, it can move swiftly, using powerful jet propulsion while flapping its enlarged fins.

Another unique behaviour that has been observed in these creatures is known as the ‘pineapple’ posture. This occurs when the squid draws its webbed tentacles up over the body to reveal sharp-looking spines, in an attempt to warn predators not to come too close. While these spines and its haunting appearance may look frightening, the vampire squid is in fact harmless. Despite what its name suggests, it is not a bloodsucker. It is not even a predator, but instead it eats marine snow and depends on the organic material that drifts down from shallower waters, which it captures using sticky cells on long, filamentous tentacles. As detrivores, vampire squid are the only known cephalopods that do not hunt and eat live animals.

This is not the only feature that sets vampire squid apart from other cephalopods. Unlike most squid, it belongs to a far more ancient lineage, for vampire squid have shown up in the fossil record as long ago as 300 million years, presenting an anatomy that is near identical to that which they possess today. The reason for this is believed to be due to their unique adaptations that have proven remarkably well-suited for a life at these depths. The isolated environment around it has changed little in 300 million years, meaning there has been no selection pressure to drive any large-scale natural selection in the species. For now, it is evolution’s near perfect solution to the harsh, unforgiving environment of the oceanic deep.