Imagine coming face to face with a cannibalistic creature that is as tall as you are and has long tentacles, a razor-sharp beak, and skin that flashes with bizarre, dazzling color. NATURE’s Encountering Sea Monsters does just that, as underwater cameraman Bob Cranston explores the remarkable world of marine creatures called cephalopods. Cephalopods include squids, cuttlefish, octopi, and nautili.

Cranston and top marine scientists dive in waters from Indonesia and Mexico to Australia and Texas, meeting up with a variety of cephalopods — from the tiny but deadly blue-ringed octopus to the giant Humboldt squid, known for its aggressive behavior, flashing light shows, and cannibalism.

Join Bob Cranston as he fearlessly reaches out and interacts with some of the ocean’s most fascinating life forms.

To order a copy of Encountering Sea Monsters, visit the NATURE Shop.

Online content for Encountering Sea Monsters was originally posted December 2005.

Blue-Ringed Octopus (Hapalochlaena maculosa)

• Type: Cephalopod
• Family: Octopodidae
• Habitat: Shallow marine waters and tide pools
• Location: Common off the coast of Australia and the western Pacific Ocean
• Diet: Crabs, fish, and mollusks
• Average lifespan in the wild: 2 years
• Size: 5-7.8 in (12.7-20 cm)
• Weight: .92 oz (26g)

With its fascinating coloring and delicate curling arms, the blue-ringed octopus may be a beautiful creature, but this small cephalopod is also deadly. The blue-ringed octopus appears grey or beige with light brown patches when it is at rest, but when agitated its 50 or 60 bright blue rings appear and pulsate with color, as a warning. Inside the salivary glands of the blue-ringed octopus live colonies of bacteria that produce tetrodotoxin, the potent neurotoxin found in pufferfish and other animals. A bite from a blue-ringed octopus can completely paralyze and kill an adult human in a matter of minutes. There is no known antidote. The octopus itself is not affected at all by the toxin-an evolutionary prerequisite for the symbiotic relationship that has developed between the blue-ringed octopus and the toxin-producing bacteria.

The blue-ringed octopus is commonly found in shallow, sandy areas surrounding the coastal reefs of Australia and the western Indio-Pacific. It is most active after dark, and spends most of its day hidden in its nest. Like all octopods, the blue-ringed octopus has no skeleton and is thus very flexible and maneuverable. It can squeeze into tiny crevices and make dens in bottles, aluminum cans, or mollusk shells. The blue-ringed octopus is also known to burrow into sand or gravel to conceal itself.

The blue-ringed octopus feeds primarily on crabs and mollusks, ambushing from behind and enveloping prey with its eight arms. Using its bird-like beak, the octopus bites a hole through its victim’s shell to inject toxic saliva. With its arms and beak, the creature tears soft pieces from the prey, sucking the rest of the meat from the shell once it becomes partially digested by the saliva.

Packets of sperm rest in the grooved tip of the male’s modified third arm, called a hectocotylus. When mating, the male slips this grooved tip under the mantle and into the oviduct of the female through a gill slit, and transfers multiple sperm packets, or spermatophores. The female lays her eggs in several unattached clumps, which she carries in her arms until they hatch. After the young emerge from their eggs, the mother dies.

Did you know: The blue-ringed octopus, like all octopuses, has three hearts and blue blood.

Related Episode: Encountering Sea Monsters

Photo © Gary Bell / Picture Quest

Cuttlefish (Sepia officinalis)

• Type: Cephalopod
• Family: Sepiidae
• Habitat: Shallow reefs and marine channels.
• Location: Globally distributed in marine waters
• Diet: Mollusks and crustaceans, especially shrimp and crab.
• Average lifespan in the wild: 1-2 years
• Size: 20-30 in (50-75 cm)
• Weight: 11 lbs (5 kg)

Cuttlefish, along with octopuses and squid, are cephalopods—animals from an ancient branch of the tree of life that have been trolling the oceans for more than 500 million years. Cuttlefish were around long before the first shark or fish ever evolved. Their cephalopod ancestors were encased in a shell that acted as protection from predators, but the modern cuttlefish has developed an even better defense: camouflage.

A cuttlefish’s skin contains over twenty million chromatophores, cells of pigment attached to miniscule muscles. By gently flexing these muscles, the cuttlefish releases pigment into the outer layer of its skin, allowing it to control its coloration and body pattern to emulate virtually any surroundings and thereby hide in plain sight. The cuttlefish’s highly specialized skin also helps it hunt, communicate, and mate. Males aggressively ripple and flash at rival males in competition for access to females. The larger and more impressive male usually wins, but sometimes a smaller male can successfully mate via female impersonation; if a small male can grab a female and quickly disguise himself to look like her, the larger male may not notice the two are mating.

Each cuttlefish has a pair of undulating fins that span the length of their body and help the creature to swim and maneuver; for any quick movements, it propels itself by shooting water from its gut. In the middle of eight forward-reaching tentacles, there is a small beak, which cuttlefish use to break open the shells of mollusks, crabs, and other crustaceans. Cuttlefish also have two longer tentacles, with a single suction cup at each tip. They use these elongated arms to grab their prey.

Cuttlefish have a short life span, but they grow quickly. They may only live one or two years, but some species can grow up to about 23 lbs (10.5 kg). Since they have such fast growth rates, cuttlefish are careful not to expend too much energy and usually spend about 95 percent of their time resting. Cuttlefish also have an internal structure called a cuttlebone that allows them to conserve energy by helping to keep them buoyant. The cuttlebone is a long, oval bone filled either with gas or liquid, depending on the time of day and cuttlefish’s desired buoyancy. These bones wash up on shore when cuttlefish die, and they are collected by people and sold as a calcium supplement treat for domesticated birds.

Cuttlefish produce a brownish ink, which they squirt to confuse predators when threatened. Humans have long used this ink in art, and the color name sepia takes its origin from the cuttlefish species name, Sepia officinalis.

Cuttlefish generally live in shallow reefs, but they can also live in channels and deeper waters up to 650 ft (about 200 m). They are distributed around the globe, and over 120 unique cuttlefish species have been discovered. New species continue to be identified, and while no cuttlefish species is currently endangered, increased fishing by humans could become a threat.

Did you know: Cephalopods are considered one of the most intelligent animals in the sea, and their cognitive abilities have been widely studied. Social learning in cuttlefish has been documented, and cuttlefish have even been trained in a lab to swim through T-shaped mazes.

Related Episode:

• Encountering Sea Monsters

They told him not to go. They told him the animals were dangerous and unpredictable. Diving at night so far offshore was also risky. But did Bob Cranston listen?

The expert underwater cameraman decided to wave off advice from local fishermen along the coast of Mexico and as a result, NATURE’s Encountering Sea Monsters includes some of the most memorable footage ever captured of the giant Humboldt squid.

“It was some pretty hairy diving at times, but it was fascinating and well worth it,” Cranston recalls.

Cranston, a veteran of filming sharks and other dangerous sea creatures, had come to the Sea of Cortez to document an animal locals call “the red devil.” In part, that’s because the Humboldt, which can reach 6 feet long and weigh up to 100 pounds, often has devilishly red skin. But the nickname is also due to the squid’s habit of hunting at night and its notoriously aggressive behavior. Schools of Humboldts have been known to test divers with their sticky tentacles and sharp beak, and blast fishermen with jets of water and purple-black ink. They have also been known to eat each other.

The photographer was aware of the Humboldt’s reputation. Several years ago, Cranston had his first encounter with this cephalopod after following local squid boats out to their nighttime fishing grounds. The fishermen use bright lanterns to lure squid to the surface, then catch them on baited hooks or snare them with specialized spears. Cranston was warned not to swim with the fearsome animals: “Some fishermen [said] the squid literally pulled men into the sea and ate them.”

Cranston dove in anyway, and was soon surrounded by the speedy, powerful animals. A mature Humboldt “can pull you around quite a bit,” Cranston says. “They’ll come up to you and kind of grab hold with their tentacles, test your strength, pull you down, kind of take a little taste. They are very inquisitive. If you resist, they’ll back off. But it is very exciting.”

This encounter made Cranston even more curious about the Humboldt. He became fascinated by the behavior of cephalopods which have special skin cells that allow it to produce a dazzling array of colors. Scientists believe the light shows are used for communication and courtship, but are not exactly sure how. While filming Encountering Sea Monsters, Cranston decided to do a little research of his own.

Cranston wanted to see if filtering his camera lights might make Humboldt squids easier to film. “We use 650 watt lights that are very bright, and this is a nocturnal animal that lives in the deep, dark ocean, so they don’t seem to like them very much. We put some red filters on, assuming that it is a color you don’t see in the deep ocean. And yes, it worked: the squid came in closer.”

Cranston also looked for a way to mimic the flashing colors the squids use to communicate. The solution? A special strobe light that looks like a light saber. “It was a creative approach,” he says.

The experiment produced a memorable moment, recorded on film. As Cranston dives 150 feet down, a curious squid suddenly rises up from deep water and, for a moment, the two make contact in the pulsing light.

“They may seem like aliens to us,” remarks Cranston, “but cephalopods are simply remarkable organisms. They are smart, clever, sophisticated. And there is such a wide variety — from little pajama squids that have tremendous personality to cuttlefish that build [and care for their] nests.”

Cranston is looking forward to capturing more tentacles with his camera. “We’re finding new kinds of cephalopods all the time,” he says, noting that researchers have identified dozens of new species in just the last few years. “So there is always something new and interesting to see.”

The blue-ringed octopus may be one of the world’s most infamous cephalopods. It’s just the size of a teacup, but it packs a potent poison that can paralyze and kill a person in hours. There is no known antidote.

In NATURE’s Encountering Sea Monsters, one of the world’s leading octopus experts introduces viewers to the delicate mating dance of this deadly resident of the South Pacific. His name is Dr. Mark Norman, and he’s a senior curator at Museum Victoria in Australia.

Dr. Norman is the author of the leading global guide on cephalopods and has played a role in discovering or describing more than 100 new species. As part of his work, Norman has scuba dived in some of the world’s richest coral reefs, crewed expeditions that have hauled specimens up from deep trenches and submerged mountain chains, and explored tidal pools brimming with life. “It’s perpetually interesting and, basically, just a tremendous amount of fun,” he says.

The blue-ringed octopus. photo © Gary Bell/PictureQuest

NATURE Online recently spoke with Dr. Norman — this time in his office.

How did you become such an expert on all things tentacled?

Well, back when I was a doctoral student in the late 1980s I was looking for a subject, and cephalopods seemed pretty interesting. It seemed like everywhere we looked there were new species, and somebody needed to describe them all.

Exactly how many kinds of cephalopods are there?

We don’t really know. But if you count all the squids, ocis (octopods), and the nautilus, so far there are probably well over 1,500. We were massively underestimating before. I mean, we’ve gone from something like a dozen species in Australia alone to more than 75, and there are probably more.

Is it hard to find new species?

Sometimes. Some of these things are little pygmy animals, very small, so you can understand why they haven’t been noticed before. But some of them are two feet wide, bright red monsters that move around under crowded city jetties. Just nobody bothered to look before. So it’s been a lot of fun.

Do you have a favorite kind?

Probably the pajama squid. It’s a little round guy, looks like a peppermint the size of a golf ball, with black and white stripes. Hides in the sand by day, comes out to feed at night. They’re just wonderful.

Is there anywhere in the ocean you can’t find a cephalopod?

Not really. They go from really deep water — they’ve been reported down to 7 kilometers (4 miles) deep, and I suspect they go deeper — to right up to the coast. They live in really warm and really cold water. It seems as long as the water’s got salt in it, they’ll get into it.

What do you like best about these animals?

I guess the idea that they are fairly vulnerable and still survive. I mean, they don’t have shells, except for the nautilus. They are a very nice meal walking around without bones. But they use very complex behaviors to survive. They live off their wits to avoid predators using mimicry, color change, and camouflage. They’ve spent 500 million years learning how to escape detection or capture. It makes them inherently interesting.

And they are skilled predators.

Oh, yes. They are excellent hunters, very capable. The only plant eater I’ve heard about was an octopus in New Guinea observed eating a banana. But generally they are super carnivores that grow fast and die young. The exception is the nautilus; they can live 20 or 30 years.

What direction are your studies moving in these days?

I’m excited by the chemistry of these animals. They appear to produce a lot of interesting and exotic compounds for hunting and for defense. So we’d like to figure out what they are and how they work.

What did you think of those first pictures of the giant squid that the Japanese got?

Spectacular. I love the idea that there are still monsters of the deep.

CephBase
http://www.cephbase.utmb.edu/
Pictures, facts, videos, and more on all living species of cephalopods.

Cephalopod News
http://zapatopi.net/cephnews/
Get the latest headlines on all things cephalopod.

Live Giant Squid Caught on Camera
http://news.bbc.co.uk/1/hi/sci/tech/4288772.stm
Read more about the giant squid story by BBC News.

Humboldt Squid
http://nationalzoo.si.edu/Animals/Invertebrates/Facts/cephalopods/FactSheets/Humboldtsquid.cfm
Learn more about the Humboldt squid — from its predator and prey to its habitat and lifespan.

Cephalopod Research
http://www.australiancephalopods.com/index.html
Learn about Dr. Mark Norman’s research on the octopus, nautilus, squid, and cuttlefish.

Bob Cranston
http://www.bobcranston.com/
More on the expert underwater cameraman who filmed NATURE’s Encountering Sea Monsters.

National Resource Center for Cephalopods
http://www.utmb.edu/nrcc/CephInfoRes.htm
Cephalopod resources by the world’s leading captive breeder.

BOOKS

Boyle, P. R. CEPHALOPODS. New York: Blackwell, 2003.

Ellis, Richard. THE SEARCH FOR THE GIANT SQUID: THE BIOLOGY AND MYTHOLOGY OF THE WORLD’S MOST ELUSIVE SEA CREATURE. New York: Penguin, 1999.

Hanlon, Roger. CEPHALOPOD BEHAVIOUR. Cambridge, UK: Cambridge University Press, 1998.

Hoyt, Erich. CREATURES OF THE DEEP: IN SEARCH OF THE SEA’S MONSTERS AND THE WORLD THEY LIVE IN. Ontario, Canada: Firefly Books, 2001.

Norman, Mark. CEPHALOPODS: A WORLD GUIDE. Melbourne, Australia: Museum Victoria, 2000.

A creature of the ocean deep takes center stage when NATURE presents The Octopus Show.

A new age of ocean exploration is lifting the veil of mystery shrouding a creature of legend — the octopus. Dreaded by sailors through the ages, this other-worldly looking denizen of the seas is surrendering the astonishing secrets that have brought it almost mythical status.

With footage of octopus species rarely, if ever, seen before — including one with giant eyes and another with antennae in place of suction cups — NATURE takes viewers into the deepest realms of the ocean for a front-row view of The Octopus Show.

In Tahiti, it is called Rogo-tumu, a tentacled sea demon who drags unsuspecting seafarers to the ocean bottom. In the Bahamas, legends abound of the Lusca, a giant sea creature that can squeeze through the smallest cracks and change color in the blink of an eye. Along the ancient Mediterranean Sea, people spoke in reverent tones of Yamm, a sea god of many heads and legs who ruled over his watery realm.

Tall tales? Perhaps. But all are based on a remarkable real animal: the octopus. NATURE’s The Octopus Show helps viewers get their tentacles around this amazingly talented but little-understood creature. It follows the efforts of Mike DeGruy, a dedicated wildlife photographer, to capture these acrobatic but often shy animals on film, both in a laboratory-built “octopus gymnasium” and in the wild, deep sea. His quest pays off with riveting — and rare — footage of octopuses at work and at play.

It’s not surprising that octopuses have captivated both filmmakers and mythmakers alike. With their bulbous, floppy heads, big eyes, and long tentacles lined with suction cups, octopuses are attention-getting. But their looks aren’t the only thing that are striking. Octopuses also exhibit behaviors — from neon-bright flashing skin colors to breathtaking jet-propelled swims — that have made scientists sit up and take notice.

Only in recent years, however, have researchers begun to better understand these animals, which are members of an ancient group of animals called cephalopods. The other members of the group — squid, cuttlefish, and the chambered nautilus — typically have some kind of external or internal shell (in squids it’s a pencil-shaped internal structure called a pen). But the over 250 known species of octopuses appear to have completely lost their hard parts, evolving instead into a firm but flexible sack of tissues.

The flexibility pays off. As NATURE’s The Octopus Show illustrates, octopuses can squeeze into amazingly small spaces to hunt or avoid predators. Captive animals have been known to hide themselves in soft drink cans, aspirin bottles, and even under the plastic floors of aquaria. The ability to fit in a tight spot pays off when hunting, as octopuses can chase small crabs, shrimp, and fish into even tiny cracks, coaxing them out with their long tentacles.

At the same time, octopuses are amazing swimmers, literally jetting themselves along by squirting water out of a biological jet engine. The speed comes in handy when it is time to escape a hungry shark. But it isn’t the only trick they have up their sleeves for avoiding predators.

Octopuses have inspired many myths.

Thanks to special cells in their skin, octopuses have the ability to change color, and even texture, on command. In the blink of an eye, they can fade into the sea floor, appearing to be just another bumpy rock. And when it comes time to mate, some octopuses advertise the fact with bright flashes of color sure to attract a partner. One Pacific Ocean octopus has even earned its name by being an especially good shape-shifter: the mimic octopus has been known to imitate everything from giant crabs and sea shells to fish and sea snakes.

This ability to adapt quickly to new situations has paid off in other ways too. Octopuses appear to inhabit virtually every kind of ocean environment, from shallow coastal waters to the deep sea. And they come in a dizzying array of shapes and sizes. Researchers believe the North Pacific octopus — known to science as Octopus dofleini — may grow to over 30 feet long and weigh 100 pounds. The smallest, on the other hand, is thought to be the Californian ocotopus (Octopus micropyrsus), which never gets more than an inch long.

Then there is the blue-ringed octopus of Australia and the South Pacific, which is noteworthy for another reason: its venom is deadly poison. A single bite from the golf-ball sized creature can paralyze breathing muscles, inducing death within minutes.

Many more kinds of amazing ocotopuses are still waiting to be discovered. Just recently, for instance, scientists accidentally discovered an octopus that has glow-in-the-dark tentacles. It will be years, however, before scientists understand why this and other octopuses do the amazing things they do.