Monthly Archives: November 2017

Minuscule ‘water bears’ are uncanny survivors

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

A drawing of a water bear, or tardigrade appeared in the scientific journal Acta Zoologica in 1981. Courtesy Acta Zoologica.

I’ve been a “Star Trek” fan from the first show in 1966 to this week when I shouted at the TV, “Hey, that’s a tardigrade!” The writers of the new series, “Star Trek Discovery,” won my heart by incorporating in the plot an adorable animal called a tardigrade, otherwise known as a water bear.

More than 1,000 species of water bears have been named, but researchers estimate there may be as many as 100,000. The reason so many of the little cuties remain to be discovered is that nearly all are microscopic. Water bears are typically 100 to 150 microns long, one micron being one one-thousandth of a millimeter. (One millimeter is the smallest we humans can see with the naked eye.) The giants of the tardigrades are 1.5 mm long.

Although they can’t swim, tardigrades are aquatic, living wherever tiny drops of fresh or salt water form. These minuscule teddy bears are found everywhere worldwide, from hot springs and glaciers to ocean floors, beaches and mountaintops, including those of Hawaii.

If a tardigrade’s film of water evaporates, the plump creature dries up and enters a state called cryptobiosis. The creature’s metabolism slows to nearly undetectable levels, increasing its normal life span of one year to 100 years or more.

In this state, water bears have survived temperatures as high as 300 degrees Fahrenheit and as low as minus 456 degrees. The animals have also lived through vacuums, intense radiation and zero oxygen. (Researchers love testing these potential space travelers.)

Two of my invertebrate zoology textbooks use the terms enchanting, endearing and cute in their introductions to water bears. The tiny teddies trudge around on four pairs of legs. The name “tardigrade” comes from Latin “tardus,” meaning slow, and “gradus,” meaning step.

A few tardigrades are carnivores, but most are plodding vegetarians, never in a hurry to run toward or away from anything.

The teeth and claws of some water bear species look fearsome. Most mouths are telescoping cones bearing needlelike spines called stylets that pierce plants’ cell walls. The contracting legs are tipped with either talons or suction cup toes, depending on the creature’s habitat.

We Trekkies must pay to watch “Star Trek Discovery” on CBS All Access. So worth it! I came home from Australia to find in an early episode a tardigrade named Ripper the size of a grizzly bear with claws and stylet teeth to match. The writers clearly boned up on water bear biology and, except for mass, got it right.

Although the story at first portrays Ripper as a flesh-shredding monster, the sweet-natured tardigrade turns out to be simply hungry and scared. The crew feeds Ripper and sets it free. Of course. It’s “Star Trek.”

Live long and prosper.

Rare white plover adopts boat harbor as winter home

Published November 25, 2017 in the
“Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

A rare white kolea has been spotted at Heeia Kea Small Boat Harbor. The bird is likely a leucistic animal, as it has nearly all white feathers but also normally colored eyes, legs and bills, as well as a few patches of color on its feathers. ©2017 Susan Scott

Forget a white Christmas. We bird lovers are dreaming of a white kolea.

Last week reader Bill Coke emailed, “Recently spotted a leucistic Pacific golden plover.” Bill saw the rare bird at Kaneohe Bay’s Heeia Kea Small Boat Harbor. When I forwarded Bill’s pictures to plover expert Wally Johnson at Montana State University, he replied, “Wow! First leucistic plover sighting, Bill. Congratulations!”

Leucism is the term for a genetic disorder in domestic and wild animals in which the creature’s skin, fur or feathers are mostly white. Besides occurring in countless bird species, leucism is seen in nearly all invertebrates, amphibians, reptiles, fish, mammals and marsupials. I once saw a gorgeous leucistic kangaroo in the Irwin family’s Australia Zoo.

“Leu” means “white” in Latin, but leucistic animals are not albinos. A different genetic mutation causes albinism, resulting in no pigment whatsoever. Because blood vessels show through colorless irises, albinos’ eyes look red.

Birds with leucism have normally colored eyes, legs and bills, and most have patches of color on some feathers.

Leucistic animals don’t usually live long. White skin, fur or feathers are like a neon sign to predators that says “EAT HERE.”

Because kolea tend to stay in one foraging site all winter, I drove to Heeia Pier hoping to see this unusual bird for myself. And there stood Blanche (my name) on the curb at the entrance to the harbor parking lot just as Bill described.

In using female pronouns for the bird, I’m guessing. At this time of year, male and female Pacific golden plovers look alike. Come spring, these migratory shorebirds shed their drab winter coats and replace them with the brilliant breeding color feathers we kolea fans so admire.

As for Blanche, time will tell what her post-molt colors will be. The bird will likely stay white, not a good hue for a ground nester in Alaska’s summer tundra. But there’s hope. Blanche fledged in the Arctic, made it to Hawaii and has established a territory.

Several readers have emailed that they are missing their neighborhood kolea this fall, and wondered whether storms in Alaska or the Pacific killed some.

In response to my email query about this, Wally replied, “Given the long flight and life on the tundra, anything is possible. Some birds missing may be just normal mortality.” (Oahu has no official kolea census.)

If you visit Blanche, please don’t startle her into flying. Because she’s so visible, the bird needs her energy to avoid the large number (I counted 35) of feral cats that people feed at Heeia Pier and park.

We might not get white Christmases here on Oahu, but this year nature gave us a gift wrapped in white.

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.