Monthly Archives: July 2014

Surfer injured getting stuck by the beak of a needlefish

Published July 28, 2014 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2014 Susan Scott

Craig swimming with needlefish ©2014 Susan Scott

Craig swimming with needlefish.

Big Island resident Michelle Chow emailed last week about an injury she suffered while surfing.

“I think I may have gotten in the way of a needlefish jumping out of the water,” Michelle wrote. “I would like to know what you think impaled my long finger.”

Michelle included a photo of the pieces the surgeon removed, and Craig (my ER doctor husband) and I agreed with Michelle. It looks like the beak of a speeding needlefish broke off in her finger.

Needlefish get their name from their long, pointed snouts fronting narrow, silver bodies. The fish never try to puncture people or anything else.

But when these lie-in-wait predators get startled by sudden movement during the day, or electric lights at night, they sometimes leap from, or rocket through, the water.

Depending on the size of the fish, this can be an impressive leap. Needlefish, close relatives of flying fish, have been clocked whizzing through the air at 37 mph. If you have the bad luck to be in the path of one of these fish missiles, you get speared.

Hawaii hosts four species of needlefish and two of their close cousins, the halfbeaks, fish with a stubby upper jaw but a long, spiky lower jaw. The fish are common in Hawaii, but because all swim just below the water’s surface, they’re easy to miss while snorkeling.

Depending on species, needlefish and halfbeaks range in size from 1 to 3 feet long. It’s often hard to tell the two kinds of fish apart. All look like sparkling spears, blue above, silver below.

Halfbeaks mostly eat seaweed, but needlefish eat fish. With a sideways lunge, needlefish snag passing prey with spiky teeth that line the upper and lower jaws.

Needlefish apparently taste good, but they aren’t a popular food fish because people find their bones an unappetizing color. For reasons unclear, needlefish bones are green.

I recently found two freshly dead needlefish heads on a North Shore beach, and the backbones sticking out were a lovely lime green.

Like flying fish, needlefish are common prey for fish predators such as tunas, jacks and barracudas.

Needlefish punctures are rare, but if you do get stabbed, see a doctor immediately. As in Michelle’s encounter with a bolting needlefish, beak fragments often break off in the wound, greatly increasing the risk of infection.

Getting banged by a blunt-nosed flying fish at high speed would be painful enough. But connecting with a needlefish gives a whole new meaning to getting needled.

needlefish

Needlefish. ©2014 Susan Scott


Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com

©2014 Susan Scott

 

Boring worms living in shells are fascinating creatures

Published July 21, 2014 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2014 Susan Scott

Cone snail shell with worm holes. Courtesy Bob Leinau

When marine biologists talk about boring worms, they don’t mean uninteresting fish bait. They’re referring to worms that bore into hard surfaces.

The subject came up in a recent email from Bob Leinau, a fellow marine animal fan. Bob wrote that his friend showed him a large, long-dead leopard cone snail shell that had what looked like holes an eighth-inch small in the top. Bob attached a photo, asking if I knew which predator made the holes.

I did not. I sent the photo and query to Jon-Paul Bingham, the UH cone snail researcher I visited recently. JP said, “It’s a boring worm, a bit like a feather duster worm in coral heads. Commonly seen on these bigger/older shells, it attaches itself to the shell while alive, so it’s some type of symbiotic arrangement. Enhanced mobility? As they grow they drill deeper into the shell.”

Most of us think of worms as limp squishy things, so the idea of them drilling holes is hard to grasp. But the marine worms that make pits in hard surfaces don’t drill as much as chew, scour and erode. And they aren’t all worms.

Take shipworms, for instance. Those wood-munchers are clams in worm’s clothing. At the front of the clam’s long, soft body are two sharp-edged shells that grind wood into particles. The clam’s foot protrudes between the shells like a tongue, advancing the clam forward.

Like termites, bacteria in the clam’s gut digest the wood’s cellulose, the main ingredient in plant cell walls.

Another borer that really is a worm is the bone-eating snot flower, a gelatinous creature with plume-bearing gills and rootlike tendrils that penetrate the bones of dead animals. The worm does this by converting seawater to an acid that breaks down bone, allowing the worm to extract its nutrients. Again, bacteria in the gut do the digesting.

For better or worse, hundreds of species of marine worms mingle with mollusks. Some are harmless squatters but others are parasites. Because they can damage and kill oysters, clams, abalones and other shellfish, parasitic worms are of great interest in aquaculture research.

I found no studies about the specific worms that live in hollows on the shells of live cone snails, but I suspect that like most borers, the worms make their hole homes by chemical means.

The advantage of setting up housekeeping on a live cone shell may be, as JP suggested, free rides. By residing on a large carnivore, the tiny worms may also gain protection from predators. What the snail gets from the worms, no one knows.

Every time I mentioned that I was researching boring worms for this week’s column, I got snorts of laughter. Fortunately the creatures live far more interesting lives than their name implies.


Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com

©2014 Susan Scott

Toxic specks of seaweed can give you a nasty rash

Would you write about the nearly invisible brown specks in the ocean that sting?” emailed a reader last week. “They travel in swarms. We encountered them at Pipeline recently. The stings result in itchy, red, round spots the next day. What are they, and are the stings treated with vinegar like jellyfish stings?”

Given the area and time of year, my guess is that the culprit is not swarms of critters, but wisps of seaweed. Here in Hawaii it’s known as stinging limu. In Australia it’s called mermaid hair and fire weed.

Stinging limu (Lyngbya majuscula) is a seaweed that grows in tropical and subtropical waters worldwide, from shallow water to about 100 feet deep. The seaweed grows in various colors in filaments 2 to 4 inches long.

On the ocean floor the species looks like matted hair attached to corals and other seaweeds. When loose in the water, stinging limu can resemble tangled threads or, when broken up, dark specks.

Sometimes stinging limu doesn’t sting. No one knows why but not all strains are toxic. When it is toxic, the seaweed contains potent chemicals that cause skin damage upon contact.

The highest number of stinging limu cases in Hawaii occur from June through September in windward swimming areas.

The seaweed grows fast in the summer months, and the steady tradewinds of the season cause surging, which dislodges seaweed from the ocean floor. Trouble comes when loose strands of stinging limu drift toward shore.

Typically, plant fragments wash inside swimsuits. Victims feel an itching or burning sensation within minutes of leaving the water or even 24 hours later. A red, sometimes blistering rash occurs, sometimes in the swimsuit’s pattern. The rash is more intense where the seaweed gets rubbed in by a suit’s elastic.

When you encounter stinging limu, get the strands off your skin as fast as possible. If you feel stinging or itching while in the water, get out and immediately remove your swimsuit. (Well, maybe wait until you get to a restroom or your car.) Wash your skin and the suit with soap and water.

Cool compresses can help relieve the pain, and over-the-counter medications such as Bena­dryl or hydrocortisone might relieve the itching.

For severe discomfort, excessive blistering, eye stings or breathing difficulty, see a doctor.

Other marine organisms such as tiny jellyfish larvae can cause similar-looking rashes, but distinguishing these from stinging limu rash is often impossible. It doesn’t matter. The treatment is the same.

In the late 1990s my physician husband and I researched this subject for our marine injury book, “All Stings Considered” (UH Press).

Research since then shows that this irritating weed also has a good side. Biochemists have discovered chemicals in the toxins that show promise as antibiotic and antifungal agents.

Thank you, readers, for loading my email inbox this summer with good questions and thought-provoking comments.

Next week’s edge-of-the-chair topic: boring worms.


Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com

©2014 Susan Scott

Summer warmth, long days spawn an abundance of fry

fish

An inch-long Hawaiian green lion fish. ©2014 Susan Scott

Two friends, former Hawaii residents, visited from Oakland last week, and we hit all of Oahu’s hot spots. Hot spots for fish watching, that is. Wild night life for us was watching TV until 10.

We snorkeled, among other places, at Shark’s Cove, Hanauma Bay, Kahe Point (nicknamed Electric Point after the power plant there) and Lani­kai’s outer reef.

The first two sites are marine sanctuaries, and the last two are not, but you don’t need signs to know that. All you have to do is get in the water. In the protected areas the fish barely move to get out of snorkelers’ paths, and some species, such as nenue (chubs), swim so close it’s hard to get a focused photo.

This kind of tameness is a learned behavior called habituation. After repeated encounters with humans where nothing bad happened, animals stop fearing us.

In areas where netting and spearing are allowed, however, the fish view us as predators, dashing for cover at the approach of a swimmer.

Even with this marked contrast in fish behavior between protected and unprotected spots, my friends and I noticed that all four places had one notable thing in common: Hawaii’s warm summer waters and long daylight hours have stimulated a baby boom.

So many colorful little fish swarmed the coral heads, it felt like we were swimming in a bowl of goldfish crackers. Butterflyfish, damselfish, tangs, cardinal fish, trumpet fish, moray eels, goatfish — all in perfect miniature. I even saw an inch-long Hawaiian green lion fish, a tiny flying gurnard and a baby scorpionfish wolf down a baby surgeonfish.

gurnard gurnard
A tiny flying gurnard & with fin for size reference. © Susan Scott
Click for larger image
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In one place, white specks dotted the water like dust motes in the afternoon sun. When I reached out to touch one, it darted away. The specks were fish or invertebrates in larval form.

Exceptions are common, but in general tropical reef fish go through three stages before adulthood: embryo, larva and juvenile.

Embryos depend entirely on the mother for nourishment, either in the yolk of the egg she produced or by a placentalike connection. When an embryo breaks free it’s called a larva (plural larvae), defined as a creature able to catch its own food.

And I mean creature. Most fish larvae have huge eyes, and each species has its own special structures (whips, spikes, feathery filaments) for respiration and locomotion. Larvae, therefore, don’t usually resemble the fish they will become, but look more like space aliens in goggles.

Larvae dart around to eat and avoid being eaten, but they can’t swim against currents. This inability to get around on their own is the definition of plankton, Greek for “wanderer.”

Both fish eggs and larvae are a huge part of the ocean’s plankton. In the next transformation, larvae become juveniles. With some exceptions, such as the parrotfish and wrasses that change color dramatically as they grow, juvenile reef fish look like minuscule adults.

The lucky ones we saw had made it to shelter on the reef. The lucky of those will make it to adulthood to start the cycle all over again.

These hot summer months are a great time to check out Hawaii’s underwater nurseries. It’s as much fun as finding Nemo.


Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com

©2014 Susan Scott