Tag Archives: shrimp

Opae ula are hardy critters, but treat them with respect

Published October 1, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser
©2016 Susan Scott

If you dig it, they will come. Not the ghosts of baseball past, but equally enchanting, the shrimp of Hawaii present: opae ula.

Also called anchialine (AN-key-ah-lin) shrimp, opae ula are half-inch-long creatures that live in underground cracks and pukas containing a mixture of fresh and sea water

When a nearshore opening, natural or human dug, appears above the shrimp’s tunnels and forms a pool, the creatures emerge from below, eat whatever is available and multiply. Mostly the shrimp live on algae that grows on their rocks, but they also eat dead insects that fall into their pools and bacteria that grow in their water.

The hardy shrimp tolerate variable degrees of salinity and can live up to 20 years with little care. The little crustaceans are usually red but can be pink, orange, yellow, white or clear. DNA studies today show that Hawaii’s opae ula consist of at least eight genetically different populations.

p1030957I’ve written about anchialine shrimp before but information about the charming native creatures and their pools was hard to find. No more. Now we can read facts about our opae ula in a $13.95 paperback titled “Hawaiian Anchialine Pools, Windows to a Hidden World” (Mutual Publishing, 2015).

The book contains just about everything everyone knows about our little shrimp, including references for those who want more details. Clearly written by Hawaii researchers — Mike Yamamoto, Thomas Iwai and Annette Tagawa — the book also has great photos.

Most people don’t see these remarkable shrimp in pools, but rather in jars, vases and other clear containers sold in Hawaii shops and online. As for buying the shrimp, the authors don’t advocate it but acknowledge that opae ula make fascinating pets and are for sale locally and on the internet.

It’s researchers’ hope that keeping opae ula at home or the office raises awareness of the importance of preserving Hawaii’s anchialine pools. Due to coastline development and thoughtless people tossing trash and fish into these special bodies of water, Hawaii’s anchialine pools and their famous native inhabitants have dwindled in number.

If you decide to host some opae ula, buy them. Collecting your own is prohibited. When buying, confirm that the shrimp have either been raised through aquaculture or come from a state permit holder with permission to collect in a particular pool.

Of the 700 or so anchialine pools left today, about 650 are on the Big Island. Maui and Oahu have a few, some listed in the book. At least one business and one research team I know have created anchialine pools by digging holes in porous seaside rock. And as if by magic, the shrimp appeared.

When you visit a Hawaii pool of dreams, prepare to be awed.

Writer none the worse after close encounter with moray

Published September 28, 2015 in the “Ocean Watch” column, Honolulu Star-Advertiser
 ©2015 Susan Scott

A moray eel is shown here, nestled below a female marbled shrimp. The eel failed to bite the unknowing snorkeler who snapped the picture, even though it easily could have. ©2015 Susan Scott

A moray eel is shown here, nestled below a female marbled shrimp. The eel failed to bite the unknowing snorkeler who snapped the picture, even though it easily could have. ©2015 Susan Scott

To people who fear moray eels: don’t. Unless you accidentally place a hand or foot right in a moray’s mouth, it will nearly always back off. Now I have photographic proof.

While snorkeling recently, I found a female marbled shrimp, one of Hawaii’s most fetching marine animals. The species’ 2- to 3-inch-long body is greenish by day, reddish at night and patterned in a stunning mosaic.

And the splendor doesn’t stop there. Purple and white stripes decorate the marbled shrimp’s legs, and bright spots on the antennae and tail shine yellow.

Marbled shrimp are popular in the aquarium trade because they’re hardy as well as beautiful. Due to the hump on the creature’s back, marbled shrimp are also known as camel, buffalo or broken-back shrimp. Some aquarists call them Saron shrimp, Saron being the shrimp’s first scientific name.


The second scientific name, marmoratus, means marbled, a name referring to the color mix.

Marbled shrimp are common, but we don’t see them often because they hide during the day. At night these walking impressionist paintings roam the reef, eating plants and animals dead or alive.

I knew my shrimp was a female because females’ front pair of legs and bodies contain furry bristles, sometimes so dense the shrimp look like they’re carrying tiny brushes. Years ago while diving with John Hoover, author of several marine animal guides, we came across a dozen of these woolly creatures. “I don’t know their real name,” he told me later, “but I call them Fuller Brush shrimp.”

Male and female marbled shrimp look so different from one another that for years I thought they were two species.

Males never wear fur coats and have a pair of ridiculously long, claw-tipped legs, reminiscent of knights’ jousting sticks. The males use those legs for the same purpose: to fight each other from a distance.


I was thrilled when I found a large female marbled shrimp posing on a coral head in the early morning light. Holding my breath, I lowered my face and camera to the shrimp by hanging onto the underside of the coral rock below it. The shrimp held still for half a dozen shots before she retreated.

Back home I downloaded my pictures — and my eyes nearly popped out of my head. Unknown to me, my darling shrimp had been on the upper lanai of a coral townhouse. So focused was I on the shrimp that I never saw its downstairs neighbor, a yellow margin moray.

I thank the Fuller Brush shrimp for modeling that day and the moray for, amazingly, not biting when my hand was virtually in its mouth. The unlikely pair gave me one of my favorite pictures.

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

©2015 Susan Scott


Gobies form partnership with shrimp for survival

Published July 1, 2013 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2013 Susan Scott
Shrimp gobies

Two gobies retreat toward a hole dug by their shrimp roomies. ©2013 Susan Scott

While waiting for my car to be serviced last week, I went through a stack of mail I had pulled from the box as I left home, and found a local marine guide I ordered. I put the book on my lap, and it opened to gobies.

“Gobies form by far the largest family of marine fishes,” the author wrote.

This came as a surprise because I see so few. Marine gobies, though, are apparently abundant. It’s just that most are so small and secretive, we snorkelers and divers rarely notice them.

The average goby is about 4 inches long, and even that’s big compared with some. The littlest goby, Trimmatom nanus, is the smallest vertebrate in the world, two-fifths of an inch long when fully grown. The tiny fish lives in the Western Pacific and Indian oceans but is not found in Hawaii.

Gobies are hard to spot because nearly every carnivore on the reef preys on them, and therefore gobies spend much of their lives hiding.

Some species live in burrows they dig themselves, using their large mouths to haul away rocks and sand. Many tuck into cracks in the reef, and others reside on coral surfaces, hovering close to a nearby hideout.

Then there are the gobies that trade labor for guard duty. Known as shrimp gobies, the fish live in pairs with a pair of snapping shrimp, two very different couples sharing a single abode.

The shrimp dig out and maintain the burrow in sand or mud, constructing an arched doorway of coral, rock or shell bits. The shrimp, nearly blind, welcome the fish as lodgers because gobies have excellent vision and serve as sentries, twitching their tails when danger approaches to warn the shrimp to duck inside.

This is symbiosis at its cutest. While snorkeling in the Tua­mo­tus, I watched two alert gobies stand guard, one on each side of the burrow, as their two shrimp roomies shoveled out clumps of sand. When I lowered my camera near the entrance, the fish backed up (pictured) and the shrimp retreated. With the lens even closer, the fish joined their shrimp pals in hiding. Seconds later I saw two bright eyes peek out, checking to see whether the coast was clear.

About 2,000 goby species exist in the world, but because their short-lived larvae don’t often survive long distances, Hawaii hosts only 34. One is a 2.5-inch-long shrimp goby, common in Kaneohe Bay’s shallow flats.

So writes John Hoover, author of the book I was reading, “The Ultimate Guide to Hawaiian Reef Fishes, Sea Turtles, Dolphins, Whales and Seals.” The new book felt like an old friend because I keep giving my copies away as gifts. This was my fifth copy.

Hoover’s book is my favorite marine reference at home and on the boat. And now it’s a favorite for making waiting-room time fly by.

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

©2013 Susan Scott

Hawaii’s largest estuary is down but far from out

Published Jul 1, 1996 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1996 Susan Scott

Last month, when a pipeline broke in Pearl Harbor, spilling bunker fuel all over the place, most of the comments I heard fell into one of three categories:

  • Curses on those oil companies.

  • Pearl Harbor is already so polluted, it hardly matters.

  • Huh?

It’s easy to blame oil companies for fossil-fuel pollution problems. They’re big, faceless corporations that everyone loves to hate.

But before cursing Chevron for this recent accident in Pearl Harbor, consider the fact that the offending pipeline was feeding the Waiau power plant, one of three on Oahu providing us with electricity. Each of us uses the product of this pipeline. And no matter how scrupulous the safeguards, accidents happen.

And what about Pearl Harbor itself? Is it already a lost cause?

No. Despite its association with World War II devastation, the Navy and runoff pollution, Pearl Harbor remains alive and kicking. The place may not be pristine, but it has still got plenty of wildlife to root for.

Take fish. Pearl Harbor is home to significant numbers of:

  • aholehole (Hawaiian flagtails)

  • papio (young jacks)

  • awa (milkfish)

  • awaaua (ladyfish)

  • kaku (barracuda)

  • amaama (mullet)

  • oopu (gobies)

Baitfish such as nehu (anchovies) and goldspotted herring also thrive in Pearl Harbor. Fishing boats with special permits regularly enter the estuary to catch these baitfish, important in the aku pole-and-line industry.

Invertebrates flourish in this harbor too. Opae (native shrimp) need this place where fresh and salt water mix. Like the stream gobies, opae life cycles are the reverse of salmon. Both gobies and shrimp spend their adult lives in fresh water, then migrate to salty areas to spawn. Pearl Harbor offers one of the few places left on Oahu where these animals can reproduce.

Pearl Harbor got its name from its abundant pearl oysters, which became scarce at the turn of the century from overharvesting and muddy agricultural runoff. Now oysters, clams and mussels have come back.

Harvesting Pearl Harbor shellfish, however, is strictly prohibited by the state Department of Health. Even in the best of circumstances, these filter-feeding bivalves can contain lethal bacteria and chemicals from fertilizers and pesticides.

And even though Pearl Harbor itself is doing well, it still receives the damaging results of a lot of human activity from up the valley.

Samoan and bluepincer crabs can be found in good numbers in Pearl Harbor these days. Because the Department of Heath no longer has the money to monitor these crabs’ meat, eat them at your own risk.

Crabs are scavengers and will eat just about anything they come across, including the tissue of dead oysters and clams.

Wjp cares if all these shellfish are thriving if we can’t eat them? The endangered waterbirds who live in the wetland refuges there are sensitive to the health of the estuary.

Pearl Harbor houses one of the few wetland nesting areas left on Oahu for native stilts, coots, moorhens and ducks.

Fortunately, the recent oil spill caused no direct wildlife deaths in the harbor.

It did, however, coat the shoreline and intertidal area around Ford Island and the Waipio Peninsula.

The first phase of the oil spill cleanup is ending. Workers are now making restoration plans and setting up systems for monitoring long-term impacts on fish, shellfish and other wildlife.

Pearl Harbor, Hawaii’s largest estuary, certainly is well worth the effort.

Marine biologist Susan Scott writes the newspaper column, “Ocean Watch”,
forthe Honolulu Star-Bulletin, www.starbulletin.com

Scientists learning more about snapping shrimp

Published June 24, 1996 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1996 Susan Scott

FOR years, snapping shrimp have been an intriguing mystery to me.

First, I couldn’t figure out what was making that crackling noise I heard when I was swimming underwater or sitting below deck in my sailboat. The distinctive sound reminded me of bacon frying.

Eventually I learned that the noise came from the forceful clicking together of the giant claw of little creatures called snapping shrimp.

“How do they hang onto the boat?” a friend asked one day when I explained the sound.

“They don’t,” I said. “They live on the bottom.”

“What are they snapping about down there?” she asked. “They sure are making a commotion.”

I shrugged. I had never read an explanation of why these 1- to 2-inch shrimp sometimes go into such snapping frenzies.

This month, however, researchers shed some light on the subject in an article in Nature magazine.

After studying 30 groups of shrimp found in 30 Belize sponges, a marine biologist learned that these creatures live in colonies similar to those of bees, ants and termites.

Like those insects, snapping shrimp have a queen who bears all the young of a colony, one in each sponge. Older colonies have more that 300 members, all offspring of one queen and maybe a single male. Other colony members are workers who defend the sponge from intruders.

Sponge homes must have good defense systems because suitable housing for snapping shrimp is limited, making competition fierce.

IN one laboratory experiment, researchers implanted each of eight sponges with a female snapping shrimp, eight of her large male workers and eight of her juveniles.

When another member of the original family was introduced into the sponge, the residing shrimp welcomed it. However, it was a different story when another species of snapping shrimp was dropped in. The residents killed it, undoubtedly with their enormous clamping claws.

So, when we hear snapping shrimp clicking and clacking like crazy, they’re likely warring with invaders of their home territory.

Not all snapping shrimp prefer sponges. Some live in grooves in coral heads, obvious in places like Hanauma Bay. Look for wavy dark lines on the top of big heads of green lobe coral.

HOW do the shrimp make these burrows? I used to shrug at that question also, but now I have a new book that offers an explanation.

The authors speculate that the grooves are the result of coral not growing in the shrimps’ tracks, while the surrounding coral grows normally. Eventually, the grooves become deep, providing good shrimp shelter.

Some snapping shrimp living in coral heads poke their big claw into hungry starfish that try to eat the coral.

In this way, a coral colony has an advantage in being landlord to a snapping shrimp.

Researchers know little about the 100 or so species of snapping shrimp found throughout the world’s tropical marine waters. This discovery of bee-style shrimp colonies is likely just one of many more to come.

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