Monthly Archives: March 2017

Shoreline gems offer a palatable mystery

Published March 18, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

It’s still unknown how these porcupinefish palates found on the North Shore by a reader change color from white to shades of amber. ©2017 Susan Scott

Last week, reader Chris emailed a photo of some caramel-colored nuggets that she and husband Matt found along a North Shore coastline. Some of the pebblelike pieces are symmetrical, with a centerline. Others are halves of these, and all bear the markings of former ridges.

The ocean had rotated and polished the stony bits into jewels, lovely as the gemstones we call tiger’s-eye. Chris wondered if I knew what they were. I did not — and the search was on. Chris, Matt and I looked in books, queried friends and searched the internet.

The couple’s friend guessed their finds might be parts of parrotfish throats, called pharyngeal mills, that grind up coral rock. They aren’t, but it gave Chris and Matt a search subject that produced a link from Sydney’s Australian Museum. Pictured there is what the museum identified as a spiny pufferfish palate from a beach in the Gulf of Carpentaria.

Hawaii hosts a pufferfish with spines that we call a porcupinefish. The largest grows to a whopping 28 inches long and weighs 17 pounds, 12 ounces (the state record).

Chris and Matt wondered why porcupinefish mouth parts would be concentrated in one area of a long beach.

It’s possible that porcupinefish are abundant in that part of the ocean, but it’s more likely that the deposits are a result of coastal currents. The ocean sorts pebbles and shells according to flow strength, shoreline shape and objects’ weights, and that area is where the water drops off its palates.

I wondered why the roof of the mouth of the big prickly fish outlasts other parts of its skeleton, but I didn’t wonder for long. I have found dead, desiccated porcupinefish on beaches and brought them home.

When I picked one up to examine its palate, the whole thing fell apart, jaw bones included. That made clear that the fish’s upper tooth, shaped like a curved razor, is fused to a ribbed rock-hard palate. The same-shaped lower tooth is also fused to an identical hard floor, an upside-down palate. Both are bone white.

Apparently, after a pufferfish dies, ocean tumbling wears away its softer bones and teeth, leaving only the solid, durable plates. Where they get their rich color is a mystery.

Porcupinefish use their formidable teeth and rock-hard palates to crush snails, sea urchins and crabs. Be wary of a trapped porcupinefish. If caught or cornered, the fish can easily take off a finger, bone and all. Of the fresh bite I once saw, the remaining forefinger was sliced as clean across as if done with a cleaver.

Chris and Matt invited me to come see their pufferfish palates and, seeing my awe, generously gave me a few. Forget diamonds, rubies and sapphires. For us, porcupinefish palates are far more precious than stones.

White terns are at home in the trees of Honolulu

Published March 13, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

Breakfast is served. Courtesy Robert Weber.

Last week I walked into Waikiki with 11 other Oahu residents, zigzagging through tourists, street performers and pamphlet-givers. But we weren’t there to people-watch. We were there to see some of our city’s most charming marine animals: white terns.

Most people don’t think of seabirds as marine animals, but they are among the most remarkable, living entirely off the ocean without living in it.

Some don’t even get wet. In a technique called air dipping, white terns snatch fish and squid from the surface, or in midair when the prey jumps. Although the terns dive to the water, they change direction and speed so fast, they get prey without submerging.

One astonishing white tern trait is the ability to hold fish crosswise in their bills and still catch more. How they open those beaks to grab a fish while keeping hold of several others is a marvel of nature.

White terns usually catch juvenile goatfish, flying fish, flying squid and needlefish but take anything they can carry. Because the birds bring fish to their chicks intact, they have enabled biologists to discover new species. That means a person had to steal a parent tern’s fish intended for its baby.

About this, Spencer Tinker, Waikiki Aquarium director from 1940 to 1972, wrote in his book “Fishes of Hawaii,” “(Gregory’s fish) is known from but a single specimen about two inches in length from Laysan Island, which was brought to the nest of a white tern on May 12, 1923. This is an example of the extreme depravity to which scientists will descend to obtain a new species, namely, taking food from a little bird.”

Regarding humans, some terns have taken the approach of our Pacific golden plovers: If you can’t beat ’em, join ’em. The last estimate of white terns gracing our city’s trees is 2,100.

White-tern citizen scientist Rich Downs led our Waikiki walking tour, sponsored by the Hawaii Audubon Society, to show us some white terns raising chicks in the trees of Waikiki. Some of the chicks are so close to people, we bird lovers worry about vandals killing them (who can forget the Kaena Point albatross massacre?). Some of that worry eased, though, when, seeing us 12 staring up at a chick, a man emerged from a nearby building.

“You’re upsetting the parent, standing there like that,” he scolded.

Honolulu’s white terns have a growing number of friends and protectors. Kapiolani Community College biology professor Wendy Kuntz and student Katie Gipson and others set up a live chick-cam on campus, www.twitch.tv/kccmanuoku, enabling us to watch a white tern family from home. Prepare to fall in love.

For maps and information about how to help the white sprites of Honolulu, see whiteterns.org.

Weird Palau find offers a lesson in flora, fauna

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

More than 2,000 tunicate species are found throughout the world, with at least 45 varieties found in Hawaii. Pictured are the green barrel sea squirt variety found in waters off Palau. ©2017 Susan Scott

I’m home from my snorkeling trips to Palau and Yap, and in sorting through my pictures, I came upon a favorite: something so new, I didn’t know whether it was plant or animal. When I showed the real thing to our knowledgeable Palauan guide, he didn’t know either, but guessed it was a kind of alga.

Soft, thimble-size barrels with pores in them didn’t look like any alga I had ever seen, but then, some weird plants grow in the world’s oceans. One common one looks like a small Japanese glass float that filled up with water and sank to the bottom. Some call this one-celled seaweed bubble algae. (Singular is alga, but no one calls it that.) I prefer its more colorful common name: sailor’s eyeball.

After a few tries of describing my mystery organism, Google came up with “green barrel tunicate, scientific name, Didemnum molle” with a photo that matched mine.

Over 2,000 tunicate species are found throughout the world, with Hawaii hosting at least 45.

Years ago, in a zoology course at UH, I learned that these filter feeders have baglike bodies with two openings. One draws water in with tiny beating hairs, and the other directs water out. This human-heart-type image was the picture I had of all tunicates.

But like so many marine invertebrates, tunicates come in various forms. Some exist in colonies, where their bag bodies join at the base. The colonies can spread over coral and rocks in matlike patches with lots of inhalant and exhalant holes for sharing food. Often this spreading, combined with brilliant colors, makes some colonial tunicate species look like sponges.

The barrels in my photos are not visibly attached to one another, but runners creeping along the rock base connect individuals and give rise to new ones.

An individual green barrel sea squirt, also known as the tall urn ascidian (a class of tunicate), can grow to 4 inches in diameter in deep water. Shallow-water communities, such as those in my photos, are less than an inch wide.

The green tinge comes from a bacterium that lives in the tunicate’s tissues. Although not technically a plant, the bacteria produce oxygen, essential to the tunicate, the same way plants do, through photosynthesis. In this symbiotic relationship, the sea squirt produces a chemical sunscreen that protects its bacteria from UV radiation.

I’m not discouraged about not knowing those little barrels were sea squirts, or that I have surely incorrectly identified some tunicates as sponges. Learning new facts about the marine world is the thrill that keeps me dunking my face in water until it hurts.

Now I need to learn another fact: how one tells a tunicate from a sponge.