Monthly Archives: August 2017

Eagle ray finds a way to soar on minus snout

Published August 26, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

A reader named Pat Goding and her West Oahu snorkeling group have become
acquainted with a spotted eagle ray that has adjusted to life without its food-finding snout,
which has been replaced by a hook. Dubbed Puggy, the plucky ray has
an unusual five stingers on its tail. Courtesy Pat Goding

Last week reader Pat Goding sent several photos of a spotted eagle ray with its snout missing. Part of what looks like a hook protrudes from the ray’s mouth below, and another metal piece sticks up, below the eyes, like a protruding tooth.

But this is not a sad story. It’s the second summer Pat and her snorkeling companions, who call themselves “The West Oahu Swim Posse,” have seen the ray. The plucky fish survived and learned how to live with its disability.

Hawaii hosts only one of the world’s several species of eagle rays. Ours grow 6 feet wide, wingtip to wingtip, with a whiplike tail up to 18 feet long. Eagle rays occasionally cheat death with those long tails. It’s common to see ray tails of various lengths with some even bent, apparently grabbed by their main predators, sharks.

Of all rays, only eagles have more than one stinger on their tails. Some individuals have just one of these defense-only weapons, but others carry up to six. Pat’s flat-faced friend has five.

Six venomous stingers look scary, but we swimmers don’t have to worry about stepping on an eagle ray. Rather than lying on the ocean floor like sting rays, eagle rays rest in a home space, swimming slowly in midwater or near the surface usually in groups of four to six. At mealtime the rays commute to deeper water to dig up some dinner.

Eagle rays have ducklike snouts that jut from below the eyes. Unlike bird beaks, though, the eagle ray’s snout is solid muscle and doesn’t open.

The fish’s mouth is below and behind the snout. Check out a normal eagle ray’s face by clicking on the image below.Arkive species - Spotted eagle ray (Aetobatus narinari)

An eagle ray’s snout is for burrowing. Spotted eagle rays find snails and other shelled animals to eat by plowing their snouts through sand. The cloudy water this creates attracts groupie fish hoping to nab a fleeing shrimp or bolting crab.

Watching an eagle ray dig is a breathtaking sight, as is seeing a squadron of these fish flying through the water in synchrony. Eagle rays are fairly common in Hawaii’s waters. I’ve even seen them in the Ala Wai Boat Harbor.

To swim, eagle rays flap their pointed, triangular fins like wings, causing someone long ago to name them after the regal eagles. Ancient Hawaiians noted the rays’ elegance by calling them hihimanu, meaning magnificent. Pat named the flat-faced ray Puggy, after her much-loved pug dog.

About the ray’s ordeal, it seems its hook wounds got infected, the flesh fell away and the snout healed flat. I didn’t think an eagle ray could live without its food-finding snout, but this one seems to be getting by just fine.

Few maimed eagle rays still fly like an eagle or look cute as a puppy, but Puggy Ray is pulling it off. This hihimanu is a magnificent fish indeed.

Spotted Eagle Ray, Mexico. ©2012 Scott R. Davis

Grotesque acorn worm helps clean sand in sea

Published August 19, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

An acorn worm leaves behind a mound of expelled sand that it has ingested while looking for organic matter. ©2017 Susan Scott

My nephew, Joe, pointed out an area of exposed sand during a low-tide walk in Australia.

“There sure is a lot of poop here,” he said.

“These piles aren’t poop,” I said, of the squiggly pyramids at our feet. “They’re sand cleaned by acorn worms.”

“What are acorn worms?”

“I would have to kill one to show you.”

I wasn’t joking. An acorn worm’s skin is so thin that when it’s full of sand, which is nearly always, the creature bursts open if you pick it up.

Besides, acorn worms aren’t exactly cute and cuddly. Each of the 70 or so species in the world’s oceans looks like a slimy piece of intestine with an acorn for a head and a neck that looks like a cervical collar, the brace people wear for neck injuries.

But even if these marine creatures won’t win any beauty contests, they’re tops in talent. The mushy housekeepers live under the surface from the shoreline to 10,000 feet, cleaning up the ocean’s organic wastes. The worms suck in sand, pick out and eat dead plant and animal material there and discharge the filtered sand in distinctive coils.

Hawaii’s acorn worms grow 1 to 18 inches long, the longer with a body diameter of 1 inch. North Carolina hosts the giant of the U.S., a worm that grows to 8 feet long and digs burrows nearly 10 feet long. The species ranges to Brazil.

An acorn worm’s rounded, muscular head does the digging. The collar serves as an anchor, and the body trails behind. Both head and collar contain glands that produce slick mucus that helps the worm slip through sand and mud.

   

Other glands make bromine, a chemical with a medicinal smell. This, along with the accumulation of iodine in the body, might protect the worm from infection and/or predators. Given that these slow-moving worms have no teeth or claws, chemicals are their only defense.

In Hawaii, Gould’s auger snail eats only acorn worms. The worm-eating livid cone snail preys on acorn worms.

An acorn worm has no brain, but some nerves. Sensory cells on the head can taste incoming particles. The mouth lies at the junction of the head and collar, and when the worm meets something inedible, it ducks its head into the collar. This closes the mouth like a plug in a drain.

The anus is where you’d expect, on the rear end.

As we walked among the endless acorn worm castings of Queensland’s Pancake Creek, Joe said, “The worms push the sand out from where?”

“From their anuses,” I said.

“Um, Aunt Susan? That’s what people call poop.”

Technically, he’s right. The mounds, called fecal casts, contain the worm’s feces. Still, those are minuscule compared with what was in the sand when the worm ingested it. Call the acorn worm’s sand coils what you will. Given my fondness for marine worms, I call them cool.

Asia market far extends American eel’s journey

Published August 12, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

It’s easy to see why harmless snake eels, such as this one, are mistaken for sea snakes. All eels are fish. ©2017 Susan Scott

I thought I knew my eels, but a recent news item in this newspaper, about a species called the American eel, left me blank.

The story was about the East Coast’s immature American eels, called elvers, wiggly little fish that are fetching up to $2,000 a pound, live, due to Asian aquaculture demands. Managers worry that such demand is jeopardizing the species.

Were baby eels named after elves? I wondered. Alas, no. The word is a merge of the 17th-century expression “eel fare,” meaning (at the time) eel journey.

The fish were well named.

As adults, American eels live in rivers, estuaries or marine coastal areas, eating insects, fish, fish eggs, crabs, worms, clams, frogs and dead animal matter, all at night. In the daytime, eels hide under rocks and logs.

Females grow to a whopping 5 feet long, and males to 3. Individuals live 15 to 20 years.

Old age for the American eel’s life is far from laid-back. When its biological clock sounds the alarm, the fish stops eating, its eyes double in size and the eel ships to sea.

This fish can breathe through its skin as well as its gills, allowing the eel to slink across wet grass and slither through mud. Mucous glands produce slime over the entire body, making the creature, well, slippery as an eel.

The eel’s destination is the Atlantic Ocean’s Sargasso Sea, a 2 million-square-mile area of warm water about 2,000 miles offshore.

It’s a one-way trip. Once there, each female releases 20 to 30 million eggs as males release sperm. Mission accomplished, the adults die.

Hatched eel eggs drift in the Gulf Stream for a year. When they reach the American coast, the transparent juveniles, 2 to 3 inches long, are called glass eels.

As the little fish head toward estuaries, swim up rivers and settle into coastlines, they turn gray-green. These 4-inchers, called elvers, are what Asian aquaculture farmers want for stock in a lucrative market for eels as food.

The American eel is the only freshwater species in North America, but Europe has a similar one, as does Japan. Dwindling stocks of those species have created poaching of American elvers along the U.S. East Coast.

Hawaii has no freshwater eels, but the reefs around us host so many marine species (42 morays, 12 congers and 17 snake eels) that I keep a separate email file just for “sea snake” sightings.

So far, only two were correct, both the yellow-bellied species that occasionally (but rarely) drifts our way on El Nino currents.

Photos are crucial for ID. A reader recently wrote, “I know you don’t think we have sea snakes in Hawaii, but believe me, I know my eels.” The blurry photo he sent was a snowflake moray.

Snowflake Moray Eel, Hanauma Bay. ©2006 Scott R Davis

That golden time of year has arrived on kolea wings

Published August 5, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

A Pacific golden plover, or kolea, pauses on Sand Island, Midway. The atoll is about 1,000 miles from the main Hawaiian Islands, to where the birds migrate from Alaska. Courtesy Luke Halpin

Writing in all caps with multiple exclamation marks is the text equivalent of shouting. But those punctuation points and uppercase letters have their moments, and here’s one: OUR KOLEA ARE BACK!!!

The birds have been trickling in all week, returning from their child-rearing chores in Alaska.

On July 25, Pacific golden plover expert Wally Johnson forwarded me an email with the subject “Plover at BYUH.” Wally wrote, “They’re starting to head back — neat! The early ones in ‘fall’ are often females, as this one appears to be. They apparently leave the guys in charge of their growing kids and zip off to enjoy the less complicated life in Hawaii. So, the cycle is turning once again — amazing.”

The next day, Niu Valley resident Peter Ehrman emailed, “This evening I spotted a kolea in the back of the valley! Don’t know if it’s a very early arriver or a straggler that never left, but it’s definitely a kolea. Thought you’d like to know.”

I do want to know. It’s an exciting end-of-summer moment when we see a plover, and especially exciting when the individual that lives on our lawn or pecks on our street returns.

Just about everything regarding these birds is remarkable, but the one fact that drops all jaws is that each season’s chicks instinctively head south by themselves. They have no guidance besides the compass in their DNA.

Chicks stay in Alaska as long as the tundra still has bugs and berries. The youngsters need to build up enough body fat to make the 3,000-mile nonstop journey to the Hawaiian Islands.

Look for these skinny youngsters in October. If the snow falls late, some chicks arrive as late as November.

It’s a rough trip for a bird that just got its wings, and making it to Hawaii is no guarantee for survival. The young must compete for grazing space with older birds, many of which guard their foraging territory aggressively.

At best about 20 percent of summer chicks live through their first year. On a more cheerful note, the ones that make it through their first year have good potential for a long and healthy life.

When I told my husband about the two plover emails I received, he asked whether I was going to write about these early-­bird arrivals.

Of course. Announcing the return to Oahu of our Pacific golden plovers is an honor I hold dear.

As another reader wrote about hearing and seeing a kolea on her neighbor’s rooftop July 26: “All is right with the world. The kolea are home.”

Thank you to all who wrote about the return of these marvelous migratory shorebirds. We may not be actually shouting, but we’re thinking it. WELCOME HOME, KOLEA!!