Tag Archives: Great Barrier Reef

Bleaching isn’t always death knell for corals

Published November 11, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

Many scientists believe that the Earth is headed for a sixth wave of mass extinctions, with humans rushing the rate. Corals will be among those affected, but one small sign of encouragement is that some corals are adapting to changing conditions. Susan Scott snorkels off Kelso Reef, Australia. Courtesy Craig Thomas

Since I returned from Australia last week, people have been asking what I think about coral reef bleaching. Do I believe humans are causing it, and, if so, can we fix it?

The questions refer to reports of corals turning white in areas of Australia’s Great Barrier Reef, and other reports about Hawaii’s reefs. Between 2014 and 2015, scientists found bleaching in 56 percent of corals off the Big Island, 44 percent off West Maui and 32 percent around Oahu.

So-called bleaching occurs when overly warm ocean water causes corals to ditch their algae. The corals’ clear bodies then expose the white calcium carbonate cups that support them.

Researchers theorize that this occurs because overheating causes the plants to make more oxygen, and too much of the gas creates free radicals, a single O instead of the usual O2. Lone oxygen atoms are toxic to animal cells.

The good news is that bleached coral isn’t necessarily dead coral. A coral can live for a while without its plants because its tentacles sting and eat passing animal plankton. When the water later cools, such as after El Nino years, live bleached corals catch algae drifting past in the water. When the plants multiply, they put the color back in corals’ cheeks.

Because bleached corals eventually need carbs, however, if the water stays warm, the corals can’t replenish their crops and die.

This isn’t the first time on Earth that corals have been in trouble. The first reefs formed 490 million years ago, and since then five mass extinctions caused by asteroids, climate change, volcanoes and sometimes more subtle changes killed all reef-building corals. The extinctions took 1 million to 2 million years each, and hundreds of millions of years for new species to evolve.

Most scientists believe we’re on the verge of a sixth extinction. The difference this time is that we humans are rushing the rate. What would normally take 140,000 years for a species to disappear now takes 100.

Homo sapiens is one of those species. In their bright white way, reef-building corals are our putting us on red alert. We are paving the road to our own extinction.

I doubt we humans will mend our ways in time. Our animal instincts to reproduce, fight, and segregate families and tribes from one another make uniting for a common cause tough.

But because species evolve to changing conditions, there’s hope. Some corals are adapting to higher water temperatures and doing just fine. Perhaps, as human and wildlife suffering escalates worldwide, our species will evolve to become less selfish.

In the meantime, there’s tremendous beauty left on the planet, and we should get out there and enjoy it. And who knows? By each of us volunteering to the charity of our choice, we may be accelerating our species’ evolution to altruism.

Spiral float is unique to 1 species of cuttlefish

Published November 4, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

Each cuttlefish species has a distinct shape, size and ridge pattern in their buoyancy bone. Cuttlefish bones from Horseshoe Bay, Magnetic Island, Queensland, Australia, are displayed. ©2017 Susan Scott

I’m home from Australia after several outstanding voyages to the outer reefs of the Great Barrier Reef Marine Park. As is often the case, though, a highlight of the trip was a beach walk where I found perfectly intact shells of two kinds of cuttlefish: the common cuttlefish (Sepia) and the ram’s horn cuttlefish (Spirula).

These weren’t rare finds because the creatures’ skeletons are common on beaches here. In collecting some of the shells, though, and looking them up in a new doorstop book I bought for the boat, I was in for a surprise. When I studied invertebrate zoology in the 1980s, I misread a textbook caption, and since then have been merrily spouting half-truths about cuttlefish.

Cuttlefish belong to a group of creatures known as cephalopods, a class of mollusk (snails, clams, etc.) that includes nautilus, squids and octopuses. About 120 species of cuttlefish live throughout the world, but you won’t find their skeletons in Hawaii or on beaches in the Americas. Cuttlefish existed before Earth’s land masses split into continents, and that process isolated cuttlefish from some ocean areas.

Cuttlefish look like roly-poly squid, both having two big eyes and 10 tentacles around the mouth that reach out and grab anything they can catch, including other cuttlefish. In turn, just about every marine predator in the world, from fish to dolphins to seabirds, eats cuttlefish.

Most people know cuttlefish from the white, oval shells called cuttlebones that we hang in our pet bird cages as calcium supplements. Pet supply companies don’t have to search hard for the product. The bones float after the cuttlefish dies, and the white rafts of every size, from 1 to 20 inches long, litter Australia’s water surfaces and beaches.

In life, the cuttlefish’s porous calcium-type bone lies under its skin along its back like a flat backbone. By adding or removing air and water in the bones’ spaces, the animal controls its buoyancy.

The tiny cuttlefish species called the ram’s horn, however, lacks a flat cuttlebone along its back. Instead, near its rear end lies an internal spiraled shell, this species’ buoyancy controller. After the ram’s horn cuttlefish dies, its spiral also floats and drifts ashore.

My decades-old error was thinking (and telling anyone who would listen) that the spiral floats were inside all cuttlefish. In fact, each cuttlefish species has its own distinct shape, size, texture and ridge pattern in its buoyancy bone. My aha moment was in learning that the 3/4-inch-tall spirals come from a single deep-sea species, and that it has the charming common name of ram’s horn cuttlefish.

This is why, even after squishing my face and blistering my heels with weeks of superb snorkeling, beach walks remain high on my list of favorite activities.

As does buying heavy, expensive marine animal guides.

Sea snakes seen sunning amid Great Barrier Reef

Published October 28, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

Sea snakes, which carry venom used to paralyze prey, can make for good swimming and snorkeling companions, if one doesn’t fear them. ©2017 Susan Scott

KELSO REEF, AUSTRALIA >> After sitting out a week of rain in Magnetic Island Marina, we’re back in flat water, moored on another of the Great Barrier Reef’s pristine outer reefs. Snorkeling here at Kelso Reef is as good as it gets, but even so, we don’t have to get in the water to be thrilled. We just stand on the deck.

While sailing between the mainland and the outer reefs these last few weeks, we’ve seen four sea snakes sunbathing on the water’s surface. Three dived before we could turn the boat around for pictures, but one, a tan-colored beauty with dark saddles on its back, totally ignored us, continuing to nap as we circled.

The 15 species of sea snakes that live on Australia’s reefs are bold, because they’re packing. All carry cobra-type venom stored in cheek glands connected to two front fangs. Injected toxin paralyzes muscles almost immediately, handy for halting fast-swimming prey, such as the bottom-dwelling fish that most snakes like to eat.

The good news is that sea snakes don’t waste their venom on snorkelers or divers. Australia reports no deaths from sea snake bites.

Even though we’ve seen sea snakes basking on the water’s surface this month, I’ve not seen a single one while snorkeling. That’s partly by chance, but it may also be because some sea snakes don’t like to travel.

In a study of olive sea snakes, the Great Barrier Reef’s most common species, researchers found the snakes’ foraging areas were only half an acre. When workers moved some individuals from their home reef to an adjacent one 200 yards away, none crossed the sandy channel to get back.

Sea Snake. New Caledonia 2006

That might explain why sea snakes are common on some reefs and absent on others, but it makes me wonder about the snakes we see basking on the surface miles from the nearest coral reefs. Maybe like us humans, some sea snakes are wanderers and others are homebodies.

All sea snakes are air breathers, but because they have one cylindrical lung nearly as long as their bodies, they can stay submerged for up to two hours.

Olive sea snakes come in shades of solid green, gray or golden yellow. Our first three snake sightings were olives. The species has light sensors on its flat, paddlelike tail, a feature that tells the snake whether its rear end is sticking out. When you’re 6 feet long, eye spots on your tail are handy for hiding under a coral head.

For us sailors, though, eyes peering through polarized sunglasses are all we need to spot a sea snake snoozing on the water’s surface.

I know I’ll never convince people who fear snakes that they’re fun snorkeling companions. But even those with phobias might appreciate seeing, from the deck of a boat, a rare marine animal in its natural element.

Or not, if it’s a snake.

Banded Sea Snake on land, New Caledonia, 2006. Courtesy Scott R. Davis

Underwater ‘banquets’ are a feast for the eyes

Published October 21, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

A giant clam sits on a bed of coral in Britomart Reef in Queensland, Australia. ©2017 Susan Scott

ORPHEUS ISLAND, AUSTRALIA >> After nearly a week of snorkeling on the outer reefs of the Great Barrier Reef Marine Park, stormy weather forced Craig and I to sail our 37-foot boat, Honu, back to the shelter of this island. Although Orpheus is also a national park with its own charming beaches, birds and reefs, we missed our giant clams.

While anchored on the reef, we had discovered a several-acre area that looked like the site of a mermaid’s banquet. Table after table was set with pink, green and lavender plate corals sitting between runners of gold and tan leather corals. In the midst of these place settings sat dazzling centerpieces: blue, green and gold giant clams.

A major downfall of these beautiful bivalves is that they’re sitting ducks, big pieces of meat that can’t run away and have only minimal defense. (They can close their shells somewhat but don’t slam shut like they do in cartoons.) Because the colorful algae in their soft tissues need sunlight to thrive, the clams grow mostly in clear, shallow water, making them easy to find, kill and eat.

Like stony corals, giant clams host algae in their tissues that grow sugars for the clams. If conditions are prime and the algae get too dense, the clam simply eats them, too.

A giant clam gathers fertilizer for its algae directly from the seawater that bathes it. Covering the soft, gaping lips of the creature is a type of tissue that can absorb ammonia, nitrate and phosphates, nutrients crucial for plant growth.

The clam breathes, and gets nutritional supplements, by inhaling water through a round siphon on one end of its soft body and sifting out tiny plants, animals and oxygen. The filtered water exits out another siphon on the clam’s opposite end.

Because giant clams grow well in tanks, aqua-farmers in Palau, the Philippines, the Cook Islands and other areas grow them for food, for the aquarium trade and to replenish reefs where people have overharvested.

Giant Clams being grown in a tank in the Cook Islands. ©2006 Scott R. Davis

Just when Craig and I were reminiscing about our amazing experience in what we named the Super Duper Royal Clam Garden, we made a joyful discovery. Near the James Cook University’s marine science center in Orpheus Island’s Pioneer Bay, researchers had planted a giant clam garden in the 1970s.

We found the man-made plot by accident while going ashore in our dinghy. From the surface we could see the 3-foot-long creatures smiling up at the sun, their oval bodies resembling iridescent place mats, and their siphons projecting from the flesh like white porcelain cups. Today 40 to 50 (my guess) mature clams thrive there.

Swank dinner parties aren’t Craig’s and my usual thing, but last week we attended two and we didn’t get a bite to eat. In giant-clam gardens the feast is for the eyes.

Colorful Giant Clams-Bora Bora, French Polynesia. ©2006 Scott R. Davis

Sailing trips in great reef marine park never get old

Published June 10, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

A soldier crab is among several varieties of crabs found in and around the Whitsunday Islands in Australia. ©2017 Susan Scott

BREAKWATER MARINA, TOWNSVILLE, AUSTRALIA >> For the last three years, as often as our work allows, Craig and I have been sailing our 37-foot ketch, Honu, in the stretch of water between the Queensland coast and Australia’s Great Barrier Reef Marine Park.

Before I came here, I would have guessed that sailing back and forth in the same area, year after year, might get old. But here, never. The reef’s 1,400-mile length is about the same distance as Kure Atoll is from the Big Island. And the distance from the Australian mainland to the park’s 3,000 reefs and 600 islands ranges from 20 to 155 miles, gaps similar to those between Oahu and neighbor islands.

Given this expanse, plus changes in seasons, tides, storms and wildlife, each trip — even to repeat places — seems entirely new.

This year Cyclone Debbie, a category-4 storm that struck the central area about two months ago, changed both the landscape and reefs of many of the Whitsunday Islands.

As we landed our dinghy at Whitehaven, a 4-mile-long beach made of powderlike silica, a material that doesn’t retain heat, we stood shocked. The majestic trees that had lined the beach now lay in tangles of trunks and branches, their bark releasing tannin in streams that rippled through the white sand with the changing tides.

The beach was still glorious, however, and we walked its length, watching birds peck at exposed worms and snails, and enjoying the firm silica squeaking beneath our feet. The national park service had already pushed back fallen trees, and cleared a trail that looped through the wrecked woods.

Hiking there became a highlight of the trip.

Inside that broken forest, endless tiny leaves sprouted from trunks, branches, air roots and soil, a stunning picture of nature’s resilience. Craig chose that bright green growth in a devastated forest as his favorite moment of the trip.

I cheated in picking my favorite, because I named a whole category of creatures: crabs. Due to persistent strong, chilly winds, we often hunkered down in anchorages, and walked on tidal flats for hours on end.

Australia’s crabs performed brilliantly. Blue-and-white soldier crabs marched in legions of thousands, and tiny sand bubbler crabs left their sand-ball art in acres of designs. When caught out, 3-inch-wide swimming crabs turned to fight us, raising their tiny claws in defiance. En guard, monsters!

I saw spider crabs, seaweed crabs and a brown crab that jumped into a muddy tide pool to hide but kept us in sight (adorably) with its tall, white eyestalks.

On Monday I’ll be back on Oahu. I’m torn between wanting to stay in Australia and longing to get back to Hawaii. How lucky I am to travel back and forth between two of the best places on Earth.

 

Ocean ‘jewels’ encompass life stories of amazing snails

Published June 3, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

Snail species, or gastropods, are abundant in the waters off Australia. The shell at upper right is from a Conus geographus, a cone snail that can kill a person with its sting. However, the sand-filled shell was indicative that the snail inside was long dead and, therefore, was safe to pick up. ©2017 Susan Scott

BRAMPTON ISLAND, QUEENSLAND, AUSTRALIA >> The combination of afternoon low tides and Cyclone Debbie’s recent stirring up of the ocean floor has sparked a new passion in me: snails.

Like all beach walkers, I’ve always enjoyed finding pretty seashells, and like all biologists, I learned about the animals called mollusks. But never have I seen snails and homes like I have this week.

Australian waters host countless snail species. Really countless. One local book claims that more than 10,000 species live here. Another shell guide reports tens of thousands.

Marine mollusks include octopuses, cuttlefish, squids and sea slugs, but those shell-less creatures don’t leave much of a legacy after they die. What gets us beachcombers excited is finding the jewel-like homes of two-shelled creatures we call clams and oysters (bivalves), and the one-shelled creatures we know as snails (gastropods).

Most people don’t include the word “snail” when talking about a shell they’ve found, but that overlooks the animal that built the stunning piece. Of the billions of empty shells cast ashore on the world’s beaches, each has its own life story.

Most snails begin their lives as tiny hatchlings that swim for days or months before settling on the ocean floor. Soon after, the baby snail’s glands secrete a hard, calcium carbonate covering, the beginning of the adult animal’s shell, around its soft body. As the animal grows, its glands enlarge the shell along its outer edge, often in a spiral.

A snail doesn’t add shell material evenly, but rather lays it down in precise places to create its own species’ shape, thickness, height and diameter. At the same time, the creature’s glands introduce pigments into the calcium carbonate that show up on the shell as spots, lines or other markings unique to the species.

Snails don’t enlarge their shells continuously, but do it in spurts. On some spiral shells you can see growth lines called sutures. In adult snails the inside whorls of broken shells reveal the snail’s nursery and its rooms during adolescence.

Besides being superb architects and sculptors, snails are math geniuses. The complex calculations of depositing each molecule of shell and each speck of color in the precise right place at the precise right time to create a species’ exclusive shell is unfathomable.

During a stretch of bad weather, we parked Honu in a marina, rented a car and drove to central Queensland to see Australia’s sapphire gem fields. The sapphires in the shops were OK, but I didn’t buy any. I prefer jewels made by snails.

Spring tides are perfect for strolling among reef

Published May 27, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

A shrimp at low tide off Australia’s Great Barrier Reef Marine Park waits for a spring tide to return and carry it away. ©2017 Susan Scott

BRAMPTON ISLAND, GREAT BARRIER REEF MARINE PARK >> For the past few days, I’ve been choosing walking over snorkeling. That might seem a poor choice given where we’re sailing. This week, however, the new moon has brought spring tides, and here off the Queensland town of Mackay, that means a 15-foot difference between the high and low. So when the tide is out, the reefs are, too.

Spring tides have nothing to do with springtime. The name comes from a centuries-old notion that during new and full moons, the water “springs” up. Here where we’ve anchored Honu, the incoming tide seemed to leap rather than spring, covering the places we walked yesterday afternoon with 15 feet of water. We must wait until this afternoon, when the tide drops to its new-moon low, to stroll with the seabirds on the exposed reef.

It sounds awful to be walking on a reef, but we aren’t. We step in sand lanes that the currents have deposited between coral heads, seaweed tufts and rocky spires. In the late afternoon sun, the smooth, water-carved sand whorls remind me of paintings by Georgia O’Keefe.

Puddles and pools remain in the lowest reef flat depressions, where fish, crabs, shrimp, snails, sea cucumbers and countless other creatures lie motionless, waiting for the tide to turn. Those left high and dry, such as giant clams, anemones and coral polyps, close up tight during their dry time.

Because spring tides occur twice a month, the animals clearly have their ways of surviving in air for hours at a time. Even so, given all the damage we humans have done to animals and their habitats, I like to offer a helping hand to my friends.

During our reef walks Craig waits patiently while I carry starfish from dry sand to water-filled depressions left by awesomely huge stingrays. We saw one of these crater makers from the dinghy on our way to the beach and judged it to be about 4 feet wide.

Craig helps with photos too, reducing ripples on the water’s surface by standing heel to heel upwind of a stunning red-orange shrimp in about 3 inches of water.

In spite of four monster feet near its burrow, the shrimp remained motionless for the photo shoot. With its brilliant colors, it seems that hiding would be a better survival strategy than holding still. Then again, movement might give away the shrimp’s position to the stone curlews, oyster catchers, sea eagles and gulls scouting the flats for food.

When sailing among the hundreds of islands in the Great Barrier Reef Marine Park, there are no activities I would choose over snorkeling or diving. Except during spring tides. Then, with pleasure, I choose walking.

Platypuses add to thrill of wildlife sightings

Published May 20, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

A platypus, a mammal of rather ordinary stature with a ducklike bill, is seen at a national park in Queensland, Australia. ©2017 Susan Scott

GREAT KEPPEL ISLAND, QUEENSLAND, AUSTRALIA >> “It’s so small.” That was our group’s first impression of the platypus we saw paddling along the surface of a creek in Carnarvon National Park. When an animal is as celebrated as the platypus, people expect something bigger than a chihuahua.

The weather had continued its stormy streak, making sailing Honu unappealing. But in Australia, to-die-for wildlife is always close by. We rented a car, drove to the national park and were soon hiking with kangaroos and wallabies, laughing with kookaburras and cockatoos, and gasping at a sugar glider’s aerial show. And even though they aren’t marine, three platypuses kindly showed up to give us an aquatic thrill.

Platypuses are freshwater animals that spend their days snoozing in riverside burrows. At dusk the creatures emerge to forage for insects, shrimp, tadpoles, mussels and snails in the streambed. In zoos, keepers often feed their platypuses yabbies, which I now know are freshwater crayfish.

Platypuses have been famous in biology lore since 1799 when an official in Australia sent a hide of the animal to Great Britain.

Scientists there thought that some jokester had sewn a duck bill to a beaver body.

The platypus bill so resembles a duck’s bill that a common name for the animal is duck-billed platypus, even though no other platypus species exits.

Nor is the bill a bill. It’s a single, flat leathery organ containing nerves that detect electrical fields generated by living prey. Sharks and electric eels also use electroreception to find food, but the platypus is one of the only mammals with that ability.

Speaking of mammals, that’s another platypus claim to fame. These little 4- to 6-pound creatures lay eggs and then nurse their hatchlings.

After mating, the female produces two eggs, which she incubates inside her body for about 28 days. Once laid, the mother curls her tail, a fat storage structure, around the eggs for another 10 days. Hatched platypus babies suck milk from two mammary patches (no nipples) on their mother’s belly.

Upon returning to Honu from our adventure inland, the wind lay down, the sun shone brightly and off we sailed to the Keppel Islands, popular anchorages in the Great Barrier Reef Marine Park. On the voyage another nonmarine species awed us all day long. Streams of exquisite blue-and-brown butterflies called blue tigers passed through Honu’s rigging while migrating from the mainland to the islands of the Great Barrier Reef.

As I write, it’s pouring rain again, but who cares? I’m in Australia.

Australian yabbies draw fishers and stingrays

Published April 29, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

Freshwater crayfish, or yabbies as they are called in Australia, serve as bait for fishermen. Yabbies are also delectable to stingrays, which smash the burrowed tunnels the yabbies live in, and also to the fish that follow the stingrays. ©2017 Susan Scott

BUNDABERG PORT MARINA, QUEENSLAND, AUSTRALIA >> I’m back in Australia getting our sailboat Honu ready for another Great Barrier Reef adventure.

To answer a common question, no, we do not sail Honu back and forth between Hawaii and here. At Honu’s average speed of 5 miles per hour, it would take 50 days, minimum, to sail the 6,000 miles between Hawaii and Australia. It’s a long, hard voyage that for us is unfeasible, timewise. So, for now, the boat stays Down Under.

That means, of course, Honu is subject to cyclones. To answer another question, Cyclone Debbie did not strike this marina, and Honu survived the torrential rains unscathed.

Because Australia has marine life I don’t know, customs I’ve not seen and language I don’t always understand, during my trips here I have my own endless questions. A recent one was: Why are people sticking hand-pump suction tools into the sand at low tide?

When I asked a friendly angler, he said, “I’m pulling up yabbies.”

I’ve been in Australia enough to know that yabby is another name for edible freshwater crayfish. (Spiny and slipper lobsters are also called crayfish here.) The beach, however, was on the ocean and the suction pipe was small.

“To eat?” I said.

“No, for bait. Look here.”

He stabbed the wet sand, pulled back the plunger and came up with a cream-colored, soft-bodied creature about 3 inches long. “There’s a yabby,” he said, handing it to me. “That big claw means it’s a male. Careful, it can give you a sharp nip.”

It looked like a shrimp to me, but then that’s the problem with common names. (Latin names have their own issues — call a yabby a Callianassa australiensis and the conversation is over.)

Australia’s bait yabbies are found along its east coast where they live in the sand between the high and low tide lines. At low tide, fishers dig near telltale holes in the sand, but that’s no guarantee the creature is there. Each adult yabby has three or four holes joining its main burrow, which can be 2 feet down.

Another question I’ve had for years in Australia is why the sand on some beaches during low tide is pocked with dozens, sometimes hundreds, of perfect stingray outlines including their long tails.

It’s yabbies again. During high tide, the rays swim over the sand flats and “puddle” the sand with strong beats of their powerful pectoral flaps. This collapses yabby burrows, bringing the now-homeless creatures to the sand’s surface. Besides being meals for the rays, the uprooted yabbies also get eaten by fish freeloaders that have followed the rays.

Every time I take a walk here in Australia, I end up with so many wildlife questions, I have to write them down. And I’m still in the marina.

Mesmerizing sea ‘squash’ part of reef mod squad

Published November 19, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott
The baler snail lives in small communities, never traveling very far from the area in which it is born, quite often in isolated areas in Black Island, Great Barrier Reef Marine Park. ©2016 Susan Scott

The baler snail lives in small communities, never traveling very far from the area in which it is born, quite often in isolated areas in Black Island, Great Barrier Reef Marine Park. ©2016 Susan Scott

Black Island, Great Barrier Reef Marine Park >> While anchored off this small, round, wooded islet, Craig and I started snorkeling on its leeward coral side and later emerged to walk the sand beach on its windward rocky side. As time passed, the tide rose so high we had to abandon the beach walk and swim over the rock bottom.

Thank heaven for big tides.

Craig touched my arm and jabbed his finger below us. “Wait,” he said, raising his head. “I lost it.”

We peered down and saw only gray rocks. And then there it was, a spaghetti squash creeping along on a black-and-white carpet. Its leading organ resembled an elephant trunk. It was hard to keep track of the animal because its appearance changed depending on viewing angle. One side of the creature’s bulbous oval shell was yellow, but the other was a rocklike gray.

The animal was a big, breathtaking snail, but what kind I did not know.

Thank heaven for field guides.

Our crawling beauty was a baler snail. “Baler” is a misspelling of the word “bailer,” dating to when Europeans first saw islanders use the shells to bail water from their canoes. The scientific name for this snail family of over 50 species is Volutidae, shortened to the common name volute.

Volutes are famous for their dramatically patterned shells, feet and tentacles, each different from one another. One endemic species here on the Great Barrier Reef is described as “a carnival of colour, the stripes and spots of its shell pale in comparison to its luridly painted foot and tentacles.”

Volutes are also famous here for species being isolated, each found on only one reef or a small group of reefs. That’s because these snails, as opposed to most others, have no planktonic stage. Their eggs hatch on the bottom as crawling juveniles that stay in the neighborhood where they were born. Being a species in only one small area makes volutes exceptionally vulnerable to extinction through pollution, cylcones and over-collecting.

Each volute walks around the ocean floor on its large muscular foot looking for clams and other snails to dig up and eat. The photos of our volute clearly show a digging claw on each side of its carpetlike foot. Its “trunk” is a water siphon through which the animal circulates water over its gills, extracting oxygen and releasing carbon dioxide.

For half an hour we watched the 12-inch-long creature slide gracefully among the rocks of its own little island.

The experience of seeing and learning about this rare creature was a highlight of our exploration of the Great Barrier Reef.

Thank heaven for baler snails.