Ben Burford, Ph.D. candidate, Hopkins Marine Station, Stanford 

If you spend enough time looking out over the ocean, there is a chance you will see marine mammals of one sort or another; perhaps a whale will spout, or a sea lion will cruise by. But unlike these air-breathers, most animals in the ocean that grow to similarly large sizes do not need to come up to the surface. This is why some of the most impressive animals that exist today are basically unknown to science—they live in the deep ocean.

I live next to the Monterey Canyon in California, where I am neighbor to one of the largest invertebrate species on the planet. But neither I, nor any of my fellow 40,000 residents on the Monterey Peninsula have ever met this neighbor. The robust clubhook squid Onykia robusta—which until recently was called Moroteuthis—is a deep-living species that can grow to over three meters (almost 10 feet) long. Like most squid, it has 10 arms—two of which are elongated to form specialized feeding tentacles. It gets its name from the rows of large hooks at the tips of its tentacles. Behind the giant squid, it is the second largest squid species in the north Pacific.

Large body size has many benefits, including protection from predators. But growing big is a challenge, particularly for squid. By virtue of their molluscan heritage, squid possess a set of traits—including high energy demand, energetically-costly locomotion, and low blood-oxygen-carrying capacity—that presumably restrict most species to smaller adult body sizes. But clearly there are exceptions.

So how does the robust clubhook squid get so big? In order to get at this question, we hope to meet this species face-to-face in its natural deep-sea habitat. It has been seen a handful of times with MBARI remotely operated vehicles (ROVs), so we know it has been in this area. Our search begins along the walls of Monterey Canyon in deep areas rich with potential prey items, such as fish and smaller squids. Should a robust clubhook squid show itself, we will use cameras mounted on the ROV to examine its behavior and how it interacts with its surroundings. How fast can it swim? How much does it breathe? How does it hunt? To what extent could it communicate with members of its species? A glimpse of one of these squid will offer a window into the lifestyle of one of the largest and least understood animals on planet Earth.