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.

There is one less mystery in the deep sea: two Japanese researchers have finally photographed a live giant squid. It’s the first time one of the world’s largest cephalopods has been documented in its ocean home.

“It is just a sensational accomplishment,” says Dr. Mark Norman, a leading squid expert who appears in NATURE’s Encountering Sea Monsters.

The giant squid has long been the stuff of legend. Mariners claimed it sank ships and plucked sailors off decks. Even scientists admit it is a very mysterious creature. Dead specimens periodically wash up on beaches, but no researchers had ever seen one alive until recently.

First image of a live giant squid, known as Architeuthis.

Over the last decade, there’s been a race to change that. Some scientists have descended in submarines, hoping to catch a glimpse of one of the several known species of giant squid, which are believed to live in deep water, a thousand feet down or more, in oceans around the globe. Others have dragged camera-laden sleds across the ocean floor, hoping to take a portrait of one of these monsters, which are believed to grow up to 40 feet long.

Two Japanese researchers, Tsunemi Kubodera of Tokyo’s National Science Museum and Kyoichi Mori of the Ogasawara Whale Watching Association, had a different idea. First, they identified an area where fishing boat captains and tourists had seen sperm whales with sucker marks on their skin, indicating a confrontation with the giant squid. They rode out to the spot on a Japanese fishing boat. Then, they lowered a hook baited with a single small squid, nearly 3,000 feet down. Also attached to the line: an automated digital camera that snapped a picture every few minutes.

The two squid hunters had little luck for years. Then, on September 30, 2004, in the waters off Japan’s Ogasawara Islands, they succeeded. A squid about 25 feet long rose from the depths and took the bait. One of its arms got snagged on the hook. For more than four hours, it struggled to get free. Finally, the snagged tentacle broke off. By the time it was all over, the camera had snapped more than 500 pictures of the squid, which scientists call Architeuthis. When they pulled up the camera, the researchers retrieved the 5-foot-long tentacle tip as a souvenir. When Mori took it off the hook, he later told reporters, it was still moving. Its suckers even stuck on to the deck.

Architeuthis’ severed tentacle

The researchers studied their photos for more than a year, then publicly released them in a scientific journal in late 2005. The team explains that the photos show the squid hovering, “flying” through the water, and aggressively wrapping its tentacles around the bait. That suggests Architeuthis is “a much more active predator than previously suspected,” perhaps used to chasing and tracking down prey rather than waiting in ambush.

The Japanese researchers “were extremely clever on every level,” says Dr. Norman, a senior curator at Museum Victoria in Australia. “My guess is that everyone is going to be breaking down their door and asking for help over the next few years.” He says the next step will be to get moving pictures of this and several other species of giant squid that live deep in the ocean.

by Irene Tejaratchi

Dolphins use sound to detect the size, shape, and speed of objects hundreds of yards away. Fascinating and complex, the dolphin’s natural sonar, called echolocation, is so precise it can determine the difference between a golf ball and a ping-pong ball based solely on density. Although humans have researched these intelligent marine mammals for decades, much of their acoustical world remains a mystery.

One of the keys to dolphin echolocation is water’s superb conduction of sound. Sound waves travel 4.5 times faster in water than they do in the air. Dolphins use this to their advantage, in ways that would make a superhero envious. Using nasal sacs in their heads, dolphins send out rapid clicks that pass through their bulbous forehead, or “melon.” The sound is focused, then beamed out in front of the dolphin. The sound wave speeds through the water, bounces off the object under investigation, and is reflected back to the dolphin. Fat-filled cavities in the dolphin’s lower jaw receive this information and auditory nerves conduct it to the middle ear and brain, where an acoustic picture is created.

Scientists say that dolphins may also use clicking to communicate with one another. Although dolphins do not possess vocal cords, they still “speak” using sounds such as whistles, squeaks, and trills. A mother dolphin may whistle to her newborn for days, apparently to imprint a signature whistle upon her baby that will enable it to recognize her. It is believed that dolphins use whistles to identify one another and possibly for other functions, such as communicating strategic alerts while hunting in a group, but scientists have yet to crack the code. Many doubt, however, that dolphins have a formal language akin to that of humans.

In the 1950s, researcher John C. Lilly helped pioneer the systematic study of dolphin vocalization. A strong advocate of interspecies communication, Lilly wrote several books about dolphins, inspired the film Day of the Dolphin (1973), and was a supporter of the Marine Mammal Protection Act of 1972. Another pioneer of dolphin research, Kenneth S. Norris, first obtained evidence of dolphin echolocation by blindfolding a bottlenose to test its ability to locate an object underwater.

Since the 1960s, American military scientists have studied dolphins, and have trained them to perform such tasks as attaching explosives and eavesdropping devices to enemy ships or submarines. In the mid-1980s, the U.S. Navy began training dolphins to search for mines using their echolocation. In 2003, dolphins were deployed for the first time in a real war situation to probe the seafloor for mines near the Iraqi port of Umm Qasr. For decades, animal activists have opposed the use of dolphins for entertainment or military activities, citing questionable training methods and the stress-related illnesses, such as ulcers, that the animals can manifest in such situations.

Dolphin advocates also object to the navy’s use of manmade sonar, which is used to scan and investigate the ocean depths, claiming that it is harming dolphins and other marine mammals. They point to incidents such as the beaching of four different whale species off the coast of the Bahamas in March 2000, following navy sonar exercises in the area. Marine mammals strand themselves for a variety of reasons, but investigations confirmed that navy sonar caused the Bahamas stranding. Researchers are not exactly sure how manmade sonar affects marine mammals. Some believe the intense sounds may scare or disorient them and cause them to rapidly flee to the water’s surface, resulting in a sort of decompression sickness that damages sensory organs and causes internal bleeding.

If technological sonar can be implicated in the death of dolphins, it would be a tragic irony, considering that the sonar is based in part upon nature and dolphins’ superior echolocation capability. Efforts to replicate dolphin echolocation continue to fall short, as humans have yet to achieve the complexity and precision that 50 million years of evolution has bestowed upon dolphins. Perhaps if scientists could understand dolphin-speak they’d have more luck, but for now the true nature of dolphin communication remains mysterious.

Dr. Edith (Edie) Widder decided she wanted to be a marine biologist when she was just 11 years old. But by the time she was in graduate school studying neurobiology, she had essentially given up the idea of fulfilling her childhood dream because of the lack of job opportunities for scientists in these fields.

Then, a chance encounter with a colony of jellyfish led Widder to her own career path investigating bioluminescence, the generation of light by living things, and building the instruments to study it and other undersea phenomena. One of the most remarkable pieces of equipment designed by Widder, who is now the president and senior scientist at Florida’s Ocean Research & Conservation Association, is the Eye-in-the-Sea, a unique, unobtrusive camera that sits on the sea bottom and records the never-before-seen behavior of marine animals.

How did you get involved in ocean research?

For my Ph.D. thesis I was measuring the electrical activity that triggers light emission from a bioluminescent dinoflagellate. As I was nearing the completion of my degree, my major professor wrote a grant for an instrument for measuring the color of very dim light flashes from bioluminescent animals. Because I have always been attracted to hi-tech instrumentation, I kept tinkering with this instrument, until I became the lab expert. At that point, he suggested I tag along on some marine biology trawling cruises and measure the colors emitted by different bioluminescent organisms. I was thrilled. Suddenly, I was doing what I had always dreamed of doing: going to sea on exploratory expeditions!

Dr. Edith (Edie) Widder inspects the Eye-in-the-Sea

The animals brought up in the nets were fantastic, and their light-producing capabilities were incredible. I was enthralled, but I still didn’t see how I could carve a career out of this new passion. One of the research cruises I participated in was organized by Dr. Bruce Robison — currently at the Monterey Bay Aquarium Research Institute (MBARI) — to test a diving suit called WASP, which had been developed for use by the offshore oil industry as a tool for ocean exploration. [The suit is big enough inside that there is a display of dials, gauges, and switches in front of the wearer's face.] I wanted to see for myself what bioluminescence in the depths of the ocean actually looked like, and Bruce gave me that opportunity. But first I had to qualify as a pilot, and one of the requirements was to be able to [screw a bolt into a large metal] shackle underwater using [only the manipulator claws of] the Michelin Man arms of the suit. The trouble was that my arms were too short, so I had to figure out a way to do it by manipulating the claws with my fingertips and switching back and forth between one arm and the other.

My dives in WASP were a life-changing experience. During my first open ocean dive, I went down to 800 feet and turned out the lights. I knew I would see bioluminescence, but I was totally unprepared for how much. It was incredible! There were explosions of light everywhere, like being in the middle of a silent fireworks display.

Were any of those dives especially noteworthy?

During one dive, I was using a light meter to measure the penetration of sunlight in the water. I was at a depth where the sunlight had almost disappeared and I had my head down looking at the red LED readout of the light meter display when suddenly the whole inside of the suit seemed to explode with blue light. It was so bright I could see all the dials and gauges inside the suit without a flashlight. I thought it was an electrical arc from something malfunctioning with the 440V that powered the suit. But it wasn’t electrical; it was biological. I had brushed against one end of a siphonophore chain, a colony of jellyfish more than 30 feet long. [Jellyfish in the subclass Siphonophorae connect into long chains, which can be over 100 feet long.] By bumping it I had stimulated its bioluminescence.

And that’s what got you hooked on ocean research?

Yes. I knew this is what I had to study, and it didn’t matter that there was no clear career path to do it. I had questions … Who’s making the light? How much light? How many organisms? Why? And, most importantly, why aren’t more scientists studying this? … and I wanted answers. I knew how much energy — the currency of life — that was required for an organism to produce light, so my subjective impression was that this has to be one of the most important processes in the ocean.

I’ve spent much of my career working with engineers to design and build the instruments I needed to answer my questions. Along the way I’ve been lucky enough to make some thrilling discoveries about who was making all that light and why, and also about what a useful tool bioluminescence is for figuring out how animals are distributed in the ocean and for monitoring the health of marine ecosystems.

When did you get the idea for Eye-in-the-Sea?

I have made hundreds of dives in submersibles, with each dive holding the promise of seeing an organism or a behavior that no one has ever seen before. But I have always wondered about the animals and behaviors that we’re not seeing because our bright lights and loud thrusters scare them away. So I decided to develop an unobtrusive camera system that used red light — which is invisible to the animals — and that was powered off a battery so that it could be left to sit quietly on the bottom of the ocean. I also wanted to test an idea for an unusual kind of lure that imitated a bioluminescent display I believed might be very attractive to large predators.

How long did it take to develop the system?

I first tried to get funding in 1994. The trouble is that it’s virtually impossible to get a grant unless you can tell the granting agency what you are going to discover. Since I had no idea, it wasn’t funded. I finally put it together with bits and pieces that we had around the lab, and a few small pots of money for different parts of the system. We had the prototype Eye-in-the-Sea developed as a student project for the Harvey Mudd College Engineering Clinic program in the fall of 2000. They produced a desktop version of the camera system. Then I got money from NOAA [the National Oceanographic and Atmospheric Administration] to build the camera housing and the frame, and I got MBARI, where I’m an adjunct, to buy the underwater battery. We used MBARI’s ship and remotely-operated vehicle for preliminary testing of the system in Monterey Canyon in 2002.

What has been the most exciting discovery made by the system?

I had wanted to place the Eye-in-the-Sea at an oasis on the bottom of the ocean, in some site rich with life that was likely to be patrolled by large predators. The first time I got to test the camera at such a place was in 2004, in the north end of the Gulf of Mexico, at an amazing location called the brine pool. This remarkable oasis is an underwater lake of water so salty and dense that it forms a pool on the bottom of the ocean. Methane, bubbling up through the pool, feeds a community of mussels and clams and other organisms that rim the shore. We placed the camera on the edge of the shore and left it there overnight. The first four hours of recordings showed fish swimming in front of the camera, apparently unperturbed by the red lights. Then, after four hours, the electronic jellyfish lure was programmed to come on for the first time. Just 86 seconds after it went into its pinwheel display mode, I recorded a squid over 6 feet long. It was not just any squid, but a squid so new to science that it cannot be placed in any known scientific family! I couldn’t have asked for a better proof of concept.

This August, we had an expedition to the Bahamas. We only had three deployments of the camera system during a nine-day cruise, but it was incredible how much we saw. We observed as many as nine different species of deep-sea shark, including a seven-gill shark, and the never-before-seen behavior of giant six-gill sharks rooting the sediment, presumably to scoop up pill bugs. We know so little about deep-sea sharks, especially about their normal behavior, that these recordings are scientific gold. As humans reach deeper into the ocean to feed a hungry planet, many of these deep dwellers are in danger of being wiped out. Their growth and reproduction are often too slow for them to be fished sustainably. We need to know about their life histories and behaviors in order to protect them.

Also on that cruise we recorded more bioluminescence than I’ve ever seen before with the Eye-in-the-Sea. Especially exciting was a series of displays that seemed to be triggered by the electronic jellyfish lure. It seemed like we were talking to something. We just don’t know what we were saying.

What does the future hold?

It’s going to be amazing when we have the Eye-in-the-Sea installed on the cabled network in Monterey Canyon. We’ll be collecting data 24 hours a day, 7 days a week. Instead of brief and infrequent glimpses, we are going to have a window into the deep sea that will be open around the clock, for months at a time. There is no telling what we may see.

Walk into the Monterey Bay Aquarium and you may find yourself surrounded by a ghostly swarm of luminous, pulsing phantoms. The specters are actually moon jellies — common marine creatures — swimming in darkened, mirrored tanks that give visitors the illusion of strolling through a shadowy ocean. “It’s a marvelous feeling — people love it,” says aquarium biologist Dr. Randy Kochevar, who appears in this week’s NATURE: Oceans in Glass: Behind the Scenes of the Monterey Bay Aquarium.

Moon jellies, however, are just one species in the aquarium’s dazzling collection of jellyfish — boneless, gelatinous creatures that may be warning us of trouble in the sea.

Jellies live in virtually every part of the ocean and come in a dizzying array of shapes, sizes, and colors. Some, like the aquarium’s box jellies, are no bigger than a thimble. Others, like the Arctic lion’s mane, have umbrella-shaped bells that reach 7 feet across and tentacles that stretch 100 feet or more. Jellies often use their tentacles to sting and snare prey, such as small fish, while drifting with the current. The flower hat jelly, another species on display in Monterey, has even grown a colorful tentacle fringe to help it lure in prey.

Not all jellies rely on their tentacles for food. Some have joined forces with specialized microorganisms that live beneath their bells. These cooperative jellies simply turn upside down and rest on the bottom of shallow seas, letting their guests soak up the rays and produce food. In tropical waters, it’s not uncommon to see thousands of these inverted, sun-loving jellies on the sea floor, creating a scene that looks a bit like a marine flower garden.

In some waters, however, an explosion in jelly populations, or blooms, has scientists worried. They say more jellies may ultimately be a sign of fewer fish — and a less healthy ocean.

One of the first warnings came more than 20 years ago, when researchers studying the Black Sea, which straddles Eastern Europe and Asia, began to notice huge numbers of a jellyfish named Aurelia aurita. They suspected these massive blooms were due to increasing pollution and massive irrigation projects that reduced the amount of fresh water flowing into the Black Sea, making it saltier.

Soon, the scientists found that the jellies were eating up to two thirds of the sea’s zooplankton (microscopic animals), which meant they were competing directly for food with several kinds of commercially important fish, including anchovies. A number of researchers believed this competition was one reason anchovy stocks had begun to dwindle.

Some help arrived in the late 1980s, when engineers increased the amount of fresh water flowing into the Black Sea, making conditions less favorable for the jellies. But the story wasn’t over. Cargo ships apparently carried another kind of jelly — a species typically found in the Atlantic — into the Black Sea, where it also began blooming in huge numbers. Ultimately, the two species began to alternate, with one numerous in some years and the second swarming in others.

As a result, “nearly all of the zooplankton production in the Black Sea appears to have gone from feeding fishes to feeding jellyfish,” concludes marine biologist Claudia Mills of the University of Washington, a leading expert on the organisms. She also believes that the jellyfish may be one reason anchovy populations remain low.

Mills and other scientists have also documented unusual jelly blooms closer to home, in the waters off Alaska and New England. In recent years, the Gulf of Mexico has also been plagued by invasions of a spotted jelly native to the Caribbean. Few people have ever seen them in such numbers — swarms so big that Gulf states have been forced to shut down parts of a shrimp fishery worth tens of millions of dollars.

The jellies are so thick that “the weight stops even a 90-foot boat cold,” one shrimper told the magazine One Earth. “It’s like crashing into a brick wall. You can’t go forward. You can’t back up, because the nets get tangled in propellers. And the nets are too heavy with jellyfish to even pull them up.” Some scientists even joke that, the way things are going, people will need to start eating jellies instead of fish or shrimp.

On a more serious note, researchers contend that the causes of jelly blooms are often mysterious, although overfishing, pollution, and climate cycles are probably playing a role. In part, the mystery is due to a lack of understanding of basic jellyfish biology. Scientists don’t know exactly how many species live, breed, and survive. At the Monterey aquarium, researchers are solving some of these riddles by raising jellies for display in a specialized “jelly farm.” The tanks allow scientists to fiddle with everything from water temperatures to food supplies to find the perfect conditions the creatures need to thrive. Eventually, they say, such studies could reveal what these ghostly, pulsing organisms are telling us about the health of the ocean.

In the early dawn of March 31, 2005, researchers from the Monterey Bay Aquarium made history. Standing on a small boat far off the coast of California, they carefully lifted a sling carrying a six-foot-long great white shark over the side and — splash! — the powerful fish was back in the wild, after spending a record 198 days at the aquarium.

As NATURE’s Oceans in Glass shows, displaying a great white — one of the sea’s most impressive predators — has long been a dream of aquariums around the world. But previous efforts to care for the sharks — which can grow to weigh two tons and measure 21 feet long — have largely ended in failure. The great whites proved too big, too aggressive, or too sensitive to live penned up. Some wouldn’t eat, says biologist Dr. Randy Kochevar of the aquarium, “and sharks can’t survive long if they aren’t feeding.”

In Monterey, however, biologists working on the aquarium’s shark conservation and ecology project believed it was possible for a great white to survive — and thrive — in one of the facility’s giant display tanks. They also believed that letting the public see these magnificent hunters up close could pay big dividends for their efforts to protect sharks, which are under increasing threat.

With this goal in mind, several years ago the aquarium’s researchers began experimenting with ways to keep a captive shark happy. First, they built an enormous 4-million-gallon pen in the ocean off Malibu, California. When commercial fishing boats accidentally caught a great white, the aquarium arranged for it and several others to be moved to the pen. There, researchers learned to feed the sharks and understand how they behaved in captivity.

Those lessons bore fruit in August 2004, when a commercial halibut fisherman caught a young, five-foot long female great white in the waters off Huntington Beach. After being held in the Malibu pen for three weeks, she was moved to the aquarium for display. Over the next six months, nearly one million people came to see her. “She was an incredible ambassador for white sharks and shark conservation,” says Kochevar.

But the young shark was also growing bigger and more restless. “She basically grew more than a foot and gained 100 pounds,” according to Kochevar. “And one day she apparently decided she needed to increase the breadth of her diet,” which consisted mostly of salmon and other fish fed to her by aquarium staff. The great white began stalking other animals in the tank, eventually attacking two smaller soupfin sharks. The staff decided it was time to release the growing animal back into the wild, but not before she provided one last service to science.

This great white shark was at the Monterey Bay Aquarium for about six months.

On their way to the release site, researchers attached a sophisticated electronic tag to the shark that would record her movements for 30 days and then pop off, transmitting its location to a satellite for retrieval. Similar tags have helped revolutionize our understanding of the habits of a myriad of animals, from sharks and sea turtles to seals and bluefin tuna. Indeed, the aquarium is part of an innovative effort — called the Tagging of Pacific Pelagics (TOPP) project — that is harnessing all kinds of marine animals to carry sensors into the ocean.

In the great white’s case, the tag worked perfectly. After popping off the shark on schedule, the tag was retrieved from surly seas off the coast of Santa Barbara by Stanford University doctoral student Kevin Weng. “They lose container ships out there!” he exclaimed after using a long-handled net to scoop the tag out of the whitecaps.

The researchers say the tag showed that after being released, the shark swam more than 100 miles offshore and to depths of greater than 800 feet. “It’s clear she survived and thrived,” says Kochevar, adding that the shark first swam several hundred miles south along the California coast, “then took a hard right and headed offshore for a while, then returned to the coast. … There’s no question that she was hunting and feeding on her own.”

Similar data from other young sharks is beginning to give scientists a picture of how these animals use the ocean and how people could improve conservation efforts, according to Kochevar. There is little question that the great white’s brief stay at the Monterey Bay Aquarium has helped stoke public support for shark research and conservation, he adds. Not long ago, the aquarium’s trustees decided to increase their shark research budget by half a million dollars.

To learn more about the TOPP project, visit http://topp.org/.