Before probing the outer reaches of our galaxy, alien hunters would be well-advised to turn their telescopes around, training them on Earth’s own cephalopods instead. The group of animals includes squid, octopus, cuttlefish and nautiluses and were seemingly jury-rigged by evolution, armed with suction cups, beaks, ink, jet propulsion, camouflage and an intelligence entirely unlike our own.

The bizarre animals are the focus of the work of Wendy Williams, a popular science writer whose work has appeared in Scientific American, the Wall Street Journal, New York Times and Boston Globe. Ms. Williams appeared at the Vineyard Haven Library on Tuesday to promote her new book, Kraken: The Curious, Exciting and Slightly Disturbing Science of Squid.

“Studying life in the ocean depths is one way to learn more about communicating with strange alien life forms out in the universe,” she said. “What could be more weird or more alien than cephalopods?”

Cephalopods are mollusks, a phylum that also includes brainless filter feeders like oysters and clams, but cephalopods are anything but. In her reporting, Ms. Williams visited the Marine Biological Laboratories in Woods Hole where neurosurgeons come every year to dissect and study the giant axon of squid, the largest nerve cell in the animal kingdom. But squid exhibit a much different intelligence from our own. Three-fifths of their neurons reside not in a central brain area but rather in their tentacles and suction cups, the latter of which are highly innervated and can be manipulated independently.

“This means the arms and tentacles can do some pretty astonishing things,” said Ms. Williams. “In many ways they seem to act of their own accord.”

Vampire squid, which inhabit the benighted sanctuaries of the deep oceans can amputate a limb when threatened. The limb then takes on a life of its own, gyrating and swimming away, glowing otherworldly blues to lure predators away from the main body.

“Another squid, to mate, takes some sperm in an appendage and severs the appendage from the main body. The appendage swims over to the female and then inserts the sperm,” she said.

In one episode in her book Ms. Williams visits a high school biology class in Newburyport where students dissecting a Humboldt squid that had been dead for two years were startled to find its spermatophores (packages of reproductive material) come to life and hop all over the table once thawed.

Perhaps most startling about some cephalopods, particularly cuttlefish, is their unmatched capacity for camouflage, an information-rich ability that requires some serious data processing. In an instant a cuttlefish can switch from a pearly white to a blackish brown or mottled tan depending on its background. Other vivid, undulating displays act as social cues.

“Sometimes the halves of one body may act independently,” she said. “There’s a male cuttlefish that during courting can flash warning-stay-away coloring on one half of its body, on the half that’s near the lurking male, but flash sweetheart-I-love-you-so-much colors on the other half that’s near the female.”

But the most evocative area of squid biology to the general public is size. Centuries of seafaring people have reported squid-like animals of a proportion unknown to biology, like the kraken of Norse lore. Speculation about such legends has only been piqued after a Mount Holyoke paleontologist recently made waves in the cephalopod world by proposing that the tidily-arranged fossilized bones of giant icthyosaurs only could have been organized by an even more massive kraken-like creature.

Ms. Williams does not entirely discount the possibility of past squid even larger than today’s giant and colossal varieties, but she says that enormous suction cup markings sometimes found on modern-day adult sperm whales can be explained as normal-sized sucker marks on juvenile sperm whales that were distorted to ominous proportions as the whale grew.

“It is possible that there were larger animals in the ocean once and they’re gone,” she said.

Still, at upwards of 40 feet, today’s largest squid can still inspire a measure of terror. One frigid February morning in Newburyport, 36-year-old Steve Atherton went for a walk on Plum Island during a northeaster and came upon a hulking mass fit for Norse legend.

“It was a squid, a huge squid, of a size unlike any he’d ever seen,” said Ms. Williams. “It seemed nearly dead but its eyes were still clear, its two feeding tentacles were missing and the thing was huge almost beyond imagination. The eyes were as large as dinner plates. They still seemed even in that deathly state to have an eerie ability to follow prey with an intense and unwavering focus.”

That giant squid, one of the few specimens extant, took a bizarre journey, first to the New England Aquarium before being exiled due to its smell, then to the Smithsonian, hauled there by biologist Clyde Roper who put the animal into a military coffin and drove it in a hearse down I-95. The squid was briefly displayed next to an elephant from Teddy Roosevelt’s African safari exploits but now resides in the Smithsonian basement where it made an unlikely cameo in a Dan Brown book.

Despite their intrinsic strangeness, Ms. Williams says that the animals’ striking if unfamiliar intelligence invites comparison with our own, even across our gaping evolutionary gulf.

“As primates we love to make eye contact — cuttlefish love to make eye contact too,” she said. “Obviously there’s some kind of intelligence there. I had many, many scientists say to me when you look into their eyes you know there’s something there.”

But just like the imagined aliens of science fiction, Ms. Williams said that cephalopods inhabit a similar region of scientific ignorance.

“When you read about squid you’ll realize that we know almost nothing,” she said.