Monthly Archives: December 2013

Tasty snail species leaves pearly shells as gifts of sea

Published December 30, 2013 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2013 Susan Scott

A great green turban snail operculum closes tight on a Tahiti reef. ©2013 Susan Scott

Also known as cat’s eyes, opercula are calcium carbonate disks connected to the snail’s muscular foot. When disturbed, the snail withdraws its foot into its shell home and slams the door behind it.

Octopuses, crabs and other predators get around this lockdown by crushing or poking holes in the snail’s shell to get at the soft animal inside. Once the snail is eaten, its buttonlike operculum falls to the ocean floor, where it either remains or washes ashore.

In the Sea of Cortez (Gulf of California), I once came across a little island that had so many nickel- and quarter-sized turban snail operculums on its beaches that I went back several times to collect them for use in art pieces. Craig and I called the islet Operculi Island, figuring that must be the plural of the Latin word operculum, which means lid. Wrong guess. The correct plurals of operculum are opercula and operculums.

In the summertime on Oahu’s North Shore beaches, I often find dime-size or smaller operculums. And last week, while watching the big surf at Sunset Beach, I found countless even smaller opercula gleaming in the sand like tiny pearl earrings.

Imagine my shock and delight then, when during a snorkeling expedition off Tahiti last fall, I found an operculum the size of a fast-food cookie. Moments later, I discovered its maker, a snail so heavy it took two hands to pick up.

The snail is the great green turban, or Turbo marmoratus, a nocturnal algae-grazer native to the Indian and Western Pacific Ocean — but not to Tahiti. Since the flesh is good to eat, and artisans value the 4-pound, 9-inch-long shells as inlay material for furniture and jewelry, the species was introduced to Tahitian waters in 1967. Today, because of overcollecting, the green turban snail is endangered in India and depleted in Tahiti.

Days after my exciting discovery in the shallows of a remote island off Tahiti, I found several sand-filled green turban shells, and, scattered nearby, their algae-covered operculums. Someone had apparently enjoyed a snail meal, and in my view left the best behind.

The two giant shells that Craig helped me collect, clean and fly home, now decorate our lanai, and their hefty operculums anchor phone-charge cords to my desk and bedside stand.

I consider my turban treasures my best presents of 2013. When it comes to gifts from the sea, Christmas is a year-round affair.


Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com

©2013 Susan Scott

Hawaii’s starfish protected from fatal wasting disease

Published December 23, 2013 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2013 Susan Scott

One of my favorite activities during visits to the Puget Sound area is starfish gazing. At the ferry docks I’m in awe of the orange, purple and red starfish sprawled on the pilings like so many ornaments, and at my husband’s family cabin on Orcas Island, I’m the first to don rubber boots at low tide and splash out on a sea star trek.

Now, sadly, starfish (aka sea stars) are in trouble, and not just in Washington state. From Southern California to Alaska, sea stars of several species are dying by the thousands from a disease called wasting syndrome. No one knows the cause of the mysterious ailment, but the stakes are high. Starfish play a key role in the health of Pacific rocky intertidal zones.

Scientists are hard at work looking for answers, a massive job given the range involved. A key element is mapping the areas affected, a project that requires information gathered from researchers and lay people alike. You can see the affected areas at data.pisco­web.org/marine1/seastardisease.

Wasting disease has not affected Hawaii’s starfish. Because a bacterium or virus is the suspected cause of the starfish illness, being more than 2,000 miles away from the sick individuals seems to be, so far, an effective quarantine.

In addition to being isolated by distance, Hawaii’s mountaintop islands and steep ocean drop-offs offer starfish few shallow marine environments, the preferred habitat of many species. Of the 1,900 or so sea star species in the world, Hawaii hosts only 20 in shallow water and 68 in deep water.

In Hawaii, snorkelers and divers see starfish, but not during every excursion and never by the dozens. Finding a star here is a treat that for me is always worth a stop.

If you pick up a starfish, it’s common to see thousands of the creature’s yellowish, water-filled tube feet, tipped with suckers, extending from grooves on the animal’s underside. You might also see a tan, jellylike mass at the center of the radiating arms. This is the creature’s stomach, turned inside out to digest its meal of a live animal, or the remains of one.

But look fast. A disturbed star quickly pulls its feet and stomach back inside its protective skin, embedded with moveable calcium carbonate rods and plates. (Please return all admired sea stars to the spot you found them, belly side down. The creatures can walk, and even turn themselves over, but it’s slow going and energy-intensive.)

If there’s hope for any beleaguered class of marine animals to make it through a crisis, though, it’s these classic symbols of the sea. Starfish have remarkable powers of regeneration. In addition to releasing sperm and eggs into the water to make new starfish, an adult star can regrow a lost arm, and in some species a detached arm can grow into a complete new starfish.

It’s hard to picture Puget Sound without sea stars hugging the pilings and festooning the tide flats. But with dozens of private and public organizations and individuals teaming up to help researchers on both coasts map and study wasting syndrome, and sea stars’ doing their part with their remarkable powers of regeneration, let’s hope we won’t have to.


Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com

©2013 Susan Scott

Neptune notwithstanding, beached whales are baffling

Published December 16, 2013 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2013 Susan Scott

A pilot whale surfaces off Hawaii island. Courtesy Robin W. Baird

No one knows whether the living whales returned safely to the open ocean or if they died and got recycled by sharks and other marine scavengers.

Nor does anyone know why pilot whales, many young and seemingly healthy, sometimes beach themselves.

With all the gloomy stories we hear about oil spills, global warming and pollution, it would be easy to blame the whales’ plight on human activity. But while some of those factors may play a part in modern standings, pilot whales swimming to their deaths on beaches is not a new phenomenon.

Around 350 B.C. Aristotle wrote about beached whales (species unknown, but pilot whales, the species most commonly stranded, are found in the Mediterranean): “It is not known why they sometimes run aground on the seashore: for it is asserted that this happens rather frequently when the fancy takes them and without any apparent reason.”

Ancient Romans believed that grounding was Neptune’s punishment to whales that behaved badly.

Whether naughty or nice, pods of pilot whales and other species, such as sperm whales, have likely been swimming to their deaths in the shallows since whales have been in the sea, about 50 million years. And not because it strikes their fancy. There’s a reason it happens. We just don’t know what it is.

That’s not for lack of trying. Researchers have been studying pilot whale carcasses for decades, and although no one knows why entire pods of the 13- to 18-foot-long whales occasionally end up on beaches, scientists have theories.

The most probable is that the whales’ navigation system malfunctions. This might be from a viral or bacterial disease that infects the pod, heavy metal pollutants, an undersea earthquake, magnetic field anomalies, unusually warm or cold oceanic currents, getting lost while fleeing predators or chasing prey, or some combination of these. Or none of the above. Research is ongoing.

There is, however, some good news. A 2012 study showed that five Australian pilot whales guided back to sea after stranding survived. This suggests that although not all individuals in a pod can be saved, some can.

Mass strandings of marine mammals touch our hearts, moving a wide variety of officials and volunteers to launch rescue attempts. It’s good to know that some of those efforts succeed.


Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com

©2013 Susan Scott

Exhibit reveals distinction, beauty of Niihau shell lei

In the past when someone mentioned Niihau shell lei, I wondered why the shells that washed up on Nii­hau beaches were special. Couldn’t a person find similar shells on other island beaches? Which snail species grew the shells? Are people still making the intricate lei? How can you tell they’re from Niihau?

Last week I got the answers to my questions, and more, in elegant fashion. I visited the Bishop Muse­um’s exhibit “Niihau Shell Lei: Ocean Origins and Living Traditions.”

The shells most prized in Niihau lei come from three minuscule marine mollusks ranging in length from about one-tenth to three-eighths of an inch. Depending on spe­cies, the tiny snails live in the sand or on plants, rocks or other animals near the ocean floor. Some species graze on algae, while others eat bits of dead plants and animals and the droppings of living organisms.

The same snail species that make the shells found on Niihau beaches also live in tide pools and shoreward areas of other Hawaiian Islands, as well as in shallow waters throughout the Pacific and Indian oceans.

After the snails die, waves and currents carry some of the empty shells to shore.

In a brochure, the Bishop Museum calls these and other micro-mollusks (shells two-fifths of an inch long or less) barometers of the sea because the creatures are supersensitive to changes in their environment. The snails’ scarcity or abundance gives researchers information about the condition of local waters.

The Pacific Ocean is apparently healthy around Nii­hau because the shells gathered for lei there are considered more durable, produce vivid colors and have shinier surfaces than those of the same species found on other islands.

Another reason Niihau shells are prized is because they’re from Niihau, an island rich in history, tradition and mystique. Nicknamed the “Forbidden Island,” Nii­hau is about 18 miles long by 3 to 6 miles wide and privately owned.

Due to a lack of jobs, Nii­hau’s population has been steadily declining (less than 70 in 2009) with many former residents now living and working on Kauai.

Some lei artists continue to create stunning lei from shells found on Niihau beaches. The lei makers, often called stringers, sort the breakable, barely visible shells by species, size and color, and use an awl-like tool to remove grains of sand from the openings. Using the same tool to make holes in the shells, the artists string, knot and tie the shells into their own unique shapes and patterns.

Prices for Niihau shell lei range from $100 to $30,000.

To preserve the integrity of this art form, Hawaii legislators passed a law in 2004 requiring that anything described as a Niihau shell lei must have 80 percent of its shells from Niihau and must be made in Hawaii.

You can learn more about this unique blend of art, culture and marine life at www.niihauheritage.org/index.html.

What’s so special about Niihau shell lei? My visit to the Bishop Museum made it clear.

The shell show runs through Jan. 27.


Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com

©2013 Susan Scott

Very few shark species pose a danger to humans

Published December 2, 2013 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2013 Susan Scott

I have friends who think that because I swam with hundreds of sharks in the Tua­mo­tus last spring, I’m exceptionally brave. But I wasn’t comfortable swimming with those sharks because I’m daring: It’s because I’ve learned to tell one species from another. And when it comes to swimming with sharks, species is everything.

The sharks I snorkeled with in the South Pacific were nearly all coral reef residents: white-tip reef shark, black-tip reef shark and gray reef shark. All three, also found in Hawaii, sometimes eat octopus and squid but mostly eat reef fish, and unless people are crowding them or spearing fish around them, reef sharks aren’t interested in humans.

Of the 400 or so shark species, the three most dangerous to people are bull sharks (not found in Hawaii), great whites (offshore and rare here) and tiger sharks, the species responsible for most bites in Hawaii.

I use the term “bite” rather than “attack,” because tiger sharks aren’t attacking when they sink their teeth into human flesh. This is simply how the fish checks whether an item it has come across is food. Unfortunately the shark’s teeth are so sharp that this checking often causes injury.

In the mid-20th century, when Hawaii had a spike in the number of shark encounters with oceangoers, a state-sanctioned culling of sharks took place. Between 1959 and 1976, anglers caught and killed 4,668 sharks. Among those were 554 tiger sharks, meaning that 4,114 sharks not implicated in wounds to humans died simply for their sharky shape. As it turned out, the tiger sharks died for no good reason, too. Even with 554 individuals removed, there was little decrease in the number of Hawaii shark incidents.

After several shark-bite fatalities occurred from 1991 through 1993, the state again considered culling. This time, though, UH researchers lobbied the Legislature to fund a tracking study on tiger sharks. Marine biologists wanted to test the assumption that tiger sharks have small, coastal home ranges.

They do not. The studies showed that the species is a roamer, crossing channels between islands and sometimes diving to 1,000 feet. This proved that as far as public safety goes, fishing for tiger sharks in the area of an incident is useless.

With Hawaii, particularly Maui, having a higher number of shark clashes in 2012 (11) and 2013 (12, with one fatality) than in previous years, UH researchers are now at it again, catching, tagging and following male, female and juvenile tiger sharks. You can follow the tagged sharks at oos.soest. hawaii.edu/pacioos/proj­ects/sharks.

To create effective management strategies, biologists must know how, when and where tiger sharks swim, feed and breed. Research is the reasonable response.

I’ve never seen a bull, great white or tiger shark while I was in the water, and if I did, I would get out fast. But if my next shark encounter is with any other species, I’ll consider it another thrilling moment of sharing the ocean with one of its most awesome native inhabitants.


Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com

©2013 Susan Scott