Monthly Archives: January 2017

Moon snails use stealth in the sand to stalk prey

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

Moon snails lurk beneath the surface of shallow to deep water, burrowing down as much as 7 inches in the sand. ©2017 Susan Scott

I love moon snail shells. They’re marble smooth, patterned in rays of soft colors, and their whirls are classic. But just because the creatures’ homes look inviting doesn’t mean the animals that built them are. Moon snails are a nightmare on clam street.

Not that we, or their prey, usually see the snails in the water. Even after snorkeling on beaches littered with moon snail shells, I’ve never seen one live. That’s because moon snails skulk underwater below the surface of the sand, sometimes as deep as 7 inches. They’re down there hunting for sand-dwelling clams, mussels and most any shelled animal they can catch, including other moons.

Moon snails, and most others, get around by rippling their muscular foot, an organ beneath them that looks like an oval throw rug. When it senses a potential meal, a moon snail can inflate its foot with sea water to four times its shell volume, throw the front over its head and, well, run.

After the foot encloses its prey, the snail drags it to the sand’s surface and goes to work: Drill, baby, drill. That soft-bodied snails can drill holes in shells is hard to fathom. But those squishy bodies hold an arsenal of daggers and chemical weapons.

Moon and other snails have an extendable flexible snout, like a tiny elephant trunk. At the end is the snail’s mouth containing a tongue lined with sharp, curved teeth.

Often the moon turns its catch so the hinge is closest to its mouth. This may be the handiest way to grip the doomed bivalve, or it may be that drilling the hole directly over the bulk of the soft tissue inside makes for efficient dining.

While the snail hangs on with its foot, it curls its tongue, teeth outward, and pushes and pulls at the site while secreting acid. When it breaks through, the mouth sucks out the prey’s organs.

You can tell a moon snail hole from other drillers, such as drupes, whelks and murexes, because moons’ are countersunk. The empty moon snail shells we find on beaches are particularly attractive because the snails spent their lives plowing through sand, which polished the shell and prevented encrusting organisms from growing on it.

The drilling skill of moon snails, and other drillers, is visible on some beaches, where countless shells bear perfect pukas.

About 250 moon snail species live in shallow to deep waters, from tropics to poles. Hawaii hosts nine species, ranging from one-half to 1-1/2 inches tall. The largest moon snails live on the North American West Coast where they grow 5-1/2 inches tall. The day I find one of those, I’ll be over the moon.

Ugly bottom dweller has its charms, slime and all

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

Susan Scott’s Christmas tree was made of painted hagfish traps, which frequently wash ashore in Hawaii. ©2017 Susan Scott

Hagfish get no respect. And they should. The eel-shaped, bottom-dwelling creatures, averaging 20 inches long, provide humans with food, clothing, wallets, a crackerjack recycling system and snot. Not many fish are so giving.

Hagfish are best known for producing great gobs of clingy mucus that reminds nearly everyone, including workers at Scripps Institute of Oceanography, of snot (goo.gl/VxDz1L).

Hagfishes’ copious slime, however, isn’t just for grossing people out. It frustrates predators. Deepwater videos show that when a shark or grouper bites a hagfish, it secretes a cloud of mucus. Because fish breathe by taking water in the mouth and out the gills, the slime clogs the gills, choking the attacker: goo.gl/Yn9Apt.

Because hagfish are blind, however, they don’t see the shark coming, and it has its teeth in the hagfish’s skin before the slime fills its gills.

But hagfish live inside a bag of loose skin, which attaches to the body in one line down the creature’s back, and in flexible connections to the mucus glands. If shark teeth puncture the skin, they don’t get the muscle beneath. Since hagfish have low blood pressure, skin bites bleed minimally and don’t appear to slow the fish down.

Baggy skin also helps hagfish, using body contortions, to squeeze through openings half the size of its diameter. This is essential because the bottom-dwelling fish wiggle into the eyes, gills and anuses of dead whales, seals and fish, eating from the inside out.

To help push itself into a puka and wipe slime off its body, a hagfish ties itself in a moving knot. If goo fills its one nostril, the fish sneezes.

Hagfish slime could save us from polyester. Its protein threads are strong as spider silk, meaning it might be a natural and renewable alternative to synthetic fibers, such as nylon and spandex, made from petroleum.

The West Coast has an active hagfish fishery. The main marketplace is Korea, where people eat them and use the skin for so-called eel-skin wallets and purses.

You might think you don’t know hagfish traps, but all Hawaii’s beachgoers do. They’re those black plastic cones with frills that come to a point. Fishers fasten these to a hole in a closed, baited bucket. The fish swim in but can’t get out. Endless numbers of these floating traps come loose from their buckets and end up on Hawaii’s beaches.

Hagfish were a frequent topic of discussion at my house recently. We had several guests over the holidays who all wondered what was up with my weird Christmas tree. It’s made of washed and painted hagfish traps.

Attempt to aid crab heals faith in humanity

Published January 14, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

Tiny mole crabs live in Hawaii, just below the sand and often along the water’s edge. A deceased female’s belly shows a mass of orange eggs clinging to it. ©2017 Susan Scott

One morning last week the news of hate crimes, science denial and war atrocities left me feeling hopeless about the human race. Wanting to block out the whole wretched world, I plugged my ears with headphones, pulled a hat down to my eyes and walked to the beach.

And something wonderful happened. Standing near the shore break, an elderly couple peered down at a tiny white object in the sand.

“We wanted to help it,” the man said, when I approached, “but we didn’t know if it could sting. It seems to be tangled in something orange.”

The creature they were trying to rescue was a charming little mole crab.

Hawaii’s cream-colored mole crabs, about 1.5 inches long, live under the sand along some shore breaks, moving up and down with the tides. The little crabs manage to survive in this turbulent area because their egg-shaped bodies are smooth, allowing water and sand to slide over them with minimal resistance.

With its strong back legs, a mole crab can dig a hole in wet sand and back into it in a split second. This happens so fast that even while watching you can lose the crab’s location. If you know what to look for, though, it’s sometimes possible to find buried mole crabs.

The crabs position themselves upright in their burrows, facing the incoming waves with two stalked eyes peeking out and a pair of feathery antennae lying flat and forward, as a kind of brace. Another pair of plumed antennae stand upright, directing water to the gills for breathing.

All four antennae filter the water washing over them, gathering tiny plants and animals, dead or alive, for food.

The mole crabs’ organs are so tiny, and the wave action so swirly, that the minuscule dimple they make in the sand is barely visible. One easy tell, though, is when a crab has found a Portuguese man-of-war. Even as waves wash back and forth over the shipwrecked creature, it looks as if its long blue tentacle is stuck in the sand.

It is. A mole crab is reeling it in to eat at its leisure. I’ve found crabs with blue tentacles rolled up on the crab’s belly like a bright skein of yarn.

The mole crab the couple found was alive, but barely. I picked her up, explaining that these filter feeders have no pincers and don’t sting. I say her because the orange mass on the abdomen was a bundle of eggs. Small holes, likely a bite, in the crab’s back proved to be fatal.

To remember those kind people, who not even knowing what it was tried to save a tiny crab’s life, I took the creature home and gave it a photo memorial. The pictures remind me to try to focus on the good side of human beings — and to take more beach walks.

Splendid pictures, research propel book

Published January 7, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

The University of Hawaii Press published Robin Baird’s book “The Lives of Hawaii’s Whales and Dolphins” in November. Cover photo of resident rough-toothed dolphins by Deron S. Verbeck/iamaquatic.com

Over the years, when I had a question about Hawaii’s whales or dolphins, I would email Robin Baird, a researcher at Cascadia Research Collective. Although this nonprofit scientific and education organization is based in Olympia, Wash., Robin and his team have been traveling here about four times a year since 1999 to study our little-known whales and dolphins.

Robin always replied quickly to my queries with the latest information and generously offered me the use of photos from the Cascadia website, cascadiaresearch.org (This site has so many out-of-this-world photos and thought-provoking articles that often hours would pass before I wrote one word.)

When Robin and I met for the first time two years ago at Hanauma Bay, we talked about how good it would be to have a book that reported Cascadia’s research and showed off those fantastic pictures.

Now we have one. In November the University of Hawaii Press published “The Lives of Hawaii’s Dolphins and Whales,” by Robin W. Baird.

This is no coffee table book, but the pictures are so amazing I can almost hear the photographers’ whoops of joy when they got many of these shots. There’s the orca carrying a bigeye thresher shark in its mouth, a family of pilot whales carrying, and grieving for, their dead calf, a false killer whale about to bite a mahimahi that was trying to hide behind the photographer — and on and on.

One of my peeves in science writing is that many researchers use jargon and passive verbs to describe what happened: “The diverse time course of the observed subjects …” Not only is this dull reading, but you don’t know who did what to whom. Not Robin. This is marine biology at its finest, detailed science told in everyday language, often in story form.

One of my favorites is the tale, with photo, of a false killer whale offering a researcher a 100-pound ahi (yellowfin tuna). This whale species has the unusual habit of sharing food, not just with each other, but with humans too if they’re nearby.

Another remarkable aspect of “blackfish,” a 17th-century fishermen’s name for five mostly black whale species, is that the females of three — killer, pilot and false killer — stop reproducing when around 40 years old and live 10, 20 or even 50 more years. The theory is that long life after menopause, which as far as we know occurs only in those whales and humans, provides experienced aunties and grandmothers to guide younger generations.

This book is a rare treasure: easy-to-read marine biology with precise science that is also a dazzling picture book. Bravo, Robin.