Monthly Archives: May 2016

Diverse array of ‘pennies’ comes from marine critters

Published May 28, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott
Australians call these foram shells mermaid’s pennies; they’re common on the Great Barrier Reef. ©2016 Susan Scott

Australians call these foram shells mermaid’s pennies; they’re common on the Great Barrier Reef. ©2016 Susan Scott

Goldsmith Island, Queensland, Australia >> While sailing north through the reefs and islands of Great Barrier Reef National Park, our routine is to sail in the morning, choose one of the nearly endless protected island anchorages, stop there for the night and explore. Although each island is rich with its own charming gangs of kangaroos, parrots and coral-ringed islets, we rarely spend more than one night in the same place. We just never know what this amazing park has in store for us down the line.

One day last week, for instance, after anchoring in a picture postcard bay, we headed to shore in our dinghy and struck it rich. Countless pennies lay scattered over the white sand.

Mermaid’s pennies, that is, according to Australians. To me they were puka shells, but odd ones. It looked as if someone had spilled a truckload of washers on the beach.

The shell washers ranged in diameter from so tiny I could barely pick them up to about an inch wide. The holes in the center also varied from none to most of the shell. Nor were these disks pure white and wavy like puka shells. Their flat surfaces came in all shades of gray, brown and cream. The shells are from a species of marine creature called a foraminifera, foram for short. Being close to the beginning of the food web, forams are vital for healthy oceans, and to human enterprises as well. Egypt’s pyramids are made of zillions of calcium carbonate foram shells squished together over geologic time. Geologists also use foram deposits as clues to the location of underground oil.

Forams deliver beauty as well, decorating some of the most exquisite shorelines on the world. Beaches in Hawaii, Palau, Bermuda and more are carpets of forams finely ground by ocean waves.

Forams are animals like bacteria are animals. They eat, reproduce, walk around, prey on other organisms and die. But even the largest ones are only a single cell. They’re like amoebas with shells arranged in countless shapes of disks, spheres, spirals and tubes. Most are too small to see with the naked eye, which is what makes the mermaid’s pennies (and the white puka shells of the South Pacific) special.

Forams line all ocean floors and drift in marine plankton in astronomical numbers. In his study, one researcher found an estimated 70,000 forams per square yard on the ocean bottom. The number is on the low side for some areas. In one place, “foram ooze” was 6,600 feet thick.

At this writing, we’ve explored beaches and reefs of about 10 islands and found shells of snail species we know and many we don’t. Curiously, we’ve seen no more mermaid’s pennies, but the handful I have make me feel rich indeed.

Clever honeyeaters boast bold hues, big sweet tooth

Published May 21, 2013 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott
A blue-faced honeyeater is a tropical bird about the size of our mynahs but with the striking colors typical of many Australian birds. This honeyeater finished the latte behind it and then stole a packet of sugar. ©2016 Susan Scott

A blue-faced honeyeater is a tropical bird about the size of our mynahs but with the striking colors typical of many Australian birds. This honeyeater finished the latte behind it and then stole a packet of sugar. ©2016 Susan Scott

KEPPEL BAY MARINA, Yeppoon, Australia >> Craig and I are back in Australia to collect our 37-foot ketch, Honu, and explore more of the Great Barrier Reef.

We’ve sailed here before, but with over 1,000 miles of reef, 300-some islands and Queensland’s east coast packed with national parks, we’ve barely scratched the surface.

Just hours after we arrived in this marina where we had left Honu, three thieves appeared. We were sitting outdoors in the marina’s restaurant, The Waterline, recovering from jet lag with double lattes, when down they swooped. They were so adorable they didn’t need to steal. I would have given them the entire restaurant.

The bandits were blue-faced honeyeaters, tropical birds about the size of our mynahs but sporting the eye-popping colors typical of so many Australian birds.

The honeyeaters’ yellowish-green backs and black-and-white chests glowed in the morning sun, but it’s their striking faces that gave these birds their name. Bright blue patches encircle yellow eyes that are constantly on the alert for food. And not just any food: Blue-faced honey-eaters are crazy about sweets including flower nectar, honey and bananas. Given this sweet tooth, the birds that live around the marina’s restaurant have learned the contents of the brown paper tubes that servers place on tables when customers order coffee or tea: delicious raw sugar.

Blue-faced honeyeaters also love milk, and have been seen regurgitating milk to their nestlings. That makes the birds also interested in leftover liquids inside cups.

The clever birds sat silent and nearly invisible in the trees above the courtyard tables, waiting for the coffee drinkers to leave. Because the staff is onto the robbers, the birds must be quick.

And quick they are. Seconds after the family next to us left, three honeyeaters swooped down, ducked their heads into the cups for the milky leftovers, grabbed a sugar packet each and were gone.

The good-natured waitress saw me taking pictures and let the birds have their prizes.

“They’re polite,” she said of the honeyeaters. “Once they get a packet, off they go.” Straight to the shoreline, we learned. The birds take the sugar packets to the water’s edge, wetting the paper for easier opening. The beach there is often littered with brown paper tubes.

As I write, Craig and I are sailing north from the area, but reluctantly, agreeing that Rosslyn Bay and the Keppel Islands are so fantastic we could spend our entire month right here. That’s why they call this barrier reef great.

Hungry trumpetfish sticks close to turtle at dinnertime

Published May 16, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott
A huge trumpetfish rests near the ocean floor, under a turtle that it uses in a kind of symbiosis called commensalism. ©2016Susan Scott

A huge trumpetfish rests near the ocean floor, under a turtle that it uses in a kind of symbiosis called commensalism. ©2016 Susan Scott

While snorkeling last week I thought I saw a remora stuck to the belly of a big turtle.

Remoras are like the family dog standing under the kitchen table waiting for a dropped tidbit, except remoras are lazier. Using the suction cup on top of their heads, remoras, or suckerfish, stick to sharks, dolphins, whales and turtles, getting free food scraps and free rides as well.

The fish swimming closely under the turtle, however, was not a remora, but a huge trumpetfish about 30 inches long. But trumpetfish are not scavengers. They’re ambush predators. In cozying up to the turtle, the trumpetfish was hiding from damselfish nibbling algae and parasites off the turtle’s shell and limbs. When one of the damselfish moved to the side of the turtle, whomp! It was gone, sucked into the trumpetfish’s expanding mouth.

Reef fish eating algae and parasites off turtles is a type of symbiosis called mutualism because both the turtle and the fish mutually benefit. One gets food. The other gets cleaned.

Famous examples of mutualism are cleaner wrasses, 4-inch-long territorial fish dressed in flashy yellow, black and purple stripes. The pattern and colors of these little fish are like neon shop signs advertising the wrasse’s service station.

Fish needing parasite removal or wound debriding come to the site and hold still while the wrasse does its work. Sometimes fish without parasites or wounds visit wrasse cleaners, letting them eat body mucus. This might gain favor with the cleaner wrasse for future visits. Or maybe it just feels good.

Wrasses don’t have a monopoly on the cleaning business. At least 111 fish and dozens of shrimp species eat parasites and tend wounds on fish. In appreciation, barracuda, moray eels, snappers and other predators don’t eat their cleaners.

Still, reef fish should trust no one. A couple of sneakers called saber-toothed blennies mimic the colors and behavior of the cleaner wrasses. When a gullible fish approaches, the blenny sinks its teeth in, getting a chunk of fin or body. The ruse works only on youngsters. Older fish know the con and steer clear of the biting blennies.

My turtle and trumpetfish were engaged not in mutualism, but in another kind of symbiosis, called commensalism. In this relationship, one species benefits (trumpetfish), and the other is neither helped nor harmed (turtle).

Before I left the water, I saw the turtle resting near the bottom, her buddy fish positioned so centrally underneath it looked like the turtle had grown a trumpetfish tail. So cute, those two. I love marine biology more every day.

Extracted teeth tell the tale of a truly extraordinary fish

Published May 9, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott
Parrotfish have protruding beaklike teeth, used to bite off pieces of coral rock to get to the algae growing on the surface, or to scrape live coral heads to get to the corals’ soft bodies. ©2016 Susan Scott

Parrotfish have protruding beaklike teeth, used to bite off pieces of coral rock to get to the algae growing on the surface, or to scrape live coral heads to get to the corals’ soft bodies. ©2016 Susan Scott

While snorkeling I found a big, pink parrotfish head bumping along the sand near the shorebreak. The freshly dead fish had such striking teeth jutting from its mouth, I picked it up for a closer look. When I clutched the rolling head, though, my fingers touched the fish’s pharyngeal mill, a special set of teeth embedded in the throat. I knew about this parrotfish trait but had never seen it. So I took the head home. After two days of bleaching, cutting, boiling, drying and scrubbing my apartment of fish smell, I had the teeth free of flesh for examination. It was well worth the work.

In addition to their rainbow-colored bodies, parrotfish resemble parrots in their protruding beaklike teeth, two massive uppers and two lowers, each pair with a gap in the middle. Parrotfish also talk, sort of, making distinct crunching sounds as they bite off pieces of coral rock. Most species eat rocks to get the algae growing on the surface. Other parrotfish excavate hard sand surfaces to get algae stubble so short it’s unavailable to other plant-eating fish.

Still other parrotfish, two in Hawaii, scrape live coral heads to eat the corals’ soft bodies. These parrotfish leave conspicuous patches in the shape of their teeth.

Whether they eat algae or live coral, parrotfish bite off more than they can chew because the nutrients they need are growing on, or living inside, chunks of solid limestone. And that’s where the pharyngeal mill comes in.

Throat teeth AKA pharyngeal mill. ©2016 Susan Scott

Throat teeth AKA pharyngeal mill. ©2016 Susan Scott

This second set of teeth in the parrotfish’s throat works like a coffee grinder. Molars on plates move back and forth, pulverizing the rocks to bits. As the tiny stones move on, the parrotfish’s digestive system extracts the nutrients, churns the rubble into fine sand and expels the grains through the anus.

In addition to their jaw-dropping beauty, these extraordinary fish change sex as needed, sleep in self-made mucus sleeping bags and play a large role in keeping our reefs healthy. Parrotfish bite marks on living coral open up spaces for other animals to settle and grow. Parrotfish also mow the reef’s lawns and supply much of the sand that houses countless fish and invertebrates.

Spearfishers have killed the good-tasting parrotfish to the point they’re now rare in Hawaii waters outside of protected areas. You can help Hawaii’s parrotfish, and in turn our coral reefs, by not spearing parrotfish or ordering them in restaurants.

Of course, without supporting tissue, my parrotfish teeth fell apart. Still, I treasure them. The little mound of teeth now sits on my shelf as a tribute to a truly remarkable fish.

Parrotfish teeth cleaned: Pharyngeal mill (top three pieces). Mouth teeth (bottom four pieces.) ©2016 Susan Scott

Parrotfish teeth cleaned: Pharyngeal mill (top three pieces). Mouth teeth (bottom four pieces.) ©2016 Susan Scott

Creatures show that gender is neither rigid nor constant

Published May 2, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott
Most anemonefish are born male and change to female as the need arises. This is a Clark’s anemonefish swimming off Palau. ©2016 Susan Scott

Most anemonefish are born male and change to female as the need arises. This is a Clark’s anemonefish swimming off Palau. ©2016 Susan Scott

North Carolina politicians recently passed a law that requires people in public buildings and schools to use the bathroom corresponding to their gender at birth. When an NPR reporter asked the Rev. Alex McFarland, a North Carolina evangelist, why he supports this legislation, he replied, “This is an issue of natural law … and natural law is the recognition that there are males and females.”

Excuse me, but what natural law would that be? It’s certainly not one of Mother Nature’s. Researchers have discovered hundreds of hermaphrodite fish species in at least 20 families, and marine invertebrate hermaphrodites are so numerable, they’re uncountable. Because animals with both testes and ovaries employ them in such a variety of ways, researchers sort hermaphrodites into three categories: those that permanently have both ovaries and testes, those that start life as males and turn into females, and those that go the other way, from female to male. And given nature, each group has variations galore.

How do these dual-sexed animals reproduce? One can barely count the ways. One example is a kind of sea bass with both testes and ovaries, and it stays that way. This fish doesn’t fertilize itself, but when it meets another of its kind, they both go off, releasing sperm half the time and eggs the other half.

Some deep-sea hermaphrodite fish do fertilize themselves. This doesn’t do much for the gene pool, but it’s handy for keeping the species going when a fish can’t find a mate.

Anemonefish have another tactic. They inhabit anemones in groups of one large male, one large female and several small, immature males. Only the two big sexually mature fish lay eggs and shed sperm.

The little anemonefish in the clan are biding their time. When the breeding female dies, her mate turns into a female, and the largest juvenile matures to become the new breeding male. If the male dies, same thing. A lucky juvenile moves on up.

Some fish that change sex can swing both ways. In Japanese reef gobies, a female in a group becomes male if the dominant male leaves. If a larger male joins the group later, the changed fish reverts to her former female form.

Parrotfish, wrasses, hagfish, lizardfish, sharks, scorpionfish and other fish families all have members of various genders, being male, female, both, in-between, and changing as the situation requires. A heading in my fish textbook says, “When the going gets tough, the tough change sex.” The Rev. McFarland’s belief that there’s a dividing line between male and female organisms on our planet is wrong. In nature, of which we humans are a part, gender is anything but clear-cut.