Monthly Archives: June 1996

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

Wildlife irony:  Protect one species, hurt others

Published June 17, 1996 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1996 Susan Scott

REMEMBER Hondo, the enormous California sea lion who set up housekeeping near Seattle’s fish ladders? Wildlife authorities have captured Hondo and two of his fat pals and sent them to Sea World of Florida in Orlando. Two other sea lion trouble-makers remain at large.

The relocating of the most glutinous sea lions from these locks may help the situation briefly but is not a permanent solution. The rich niche left empty by this transfer won’t be empty for long.

So what can people do to save the trout? University of Washington engineering students are pondering this question as part of their term projects this year. Some suggestions are:

  • Make a refuge near the ladders in the form of an artificial reef. The idea is that the fish can hide in it, then make a dash for the ladder when the coast is clear. (Biologists say they don’t know whether the fish would use such a haven.)

  • Tag sea lions with a device that would deliver an electric shock if they get close to the ladder. (Good idea, but who’s going to catch and tag those enormous, numerous animals?)

This problem clearly shows the intricacy of natural systems and how hard it is to fix them once spoiled. We protected one group of animals, sea lions, resulting in another, trout, taking a hit.

In seal news closer to home, the baby monk seal born in April at Marine Corps Base Hawaii in Kaneohe is alive, well and now weaned. The mother nursed the pup for 53 days (the usual is 39 days), then took off, leaving a fat male offspring to fend for himself.

Honolulu’s National Marine Fisheries Service biologists have decided to leave the pup at the remote beach where he was born rather than move him to the isolated Northwestern Hawaiian Islands. The reasoning goes that he came to be there naturally, has plenty of fat to burn while learning to eat, and existing marine mammal and fishing laws should protect him on Oahu.

The most dangerous fishing practice to the pup, and any monk seal, is Hawaii’s inshore gill nets. State law requires that anglers inspect such nets at least every two hours. Also, the nets may not stay in one location longer than four hours in any 24-hour period.

Another good reason for leaving Oahu’s newest seal where he was born is to give people a chance to see this rare and endangered species. People in Kaneohe Bay are most likely to see the little guy, easy to recognize by the red tags on his rear flippers.

The best way to help this animal is to spread the word that’s it’s harmful to the animal (and illegal) to approach or otherwise disturb a monk seal. Never feed a seal. If these seals associate humans with food, the animals can get in trouble by approaching fishing boats or divers.

As for humans who want to avoid trouble in the water, the Hawaii Lifeguard Association has started its summer Junior Lifeguard Program. This five-day course teaches teens ocean and beach skills, including an introduction to water safety, CPR, first air and surf-rescue techniques.

The program is open to teens 13 to 17 years old who already have basic swimming skills. The weeklong sessions run through the beginning of August.

The teachers are city lifeguards. I have had the pleasure of watching some of these lifeguards work and teach and was impressed with their skills, professionalism and friendliness.

For information, call 395-3994 (Windward), 924-3313 (Ala Moana) or 695-8967 (Pokai). The North Shore course is already sold out. Suggested donation is $25.


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

 

‘Lagoon’ cartoon critters have real counterparts

Published June 10, 1996 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1996 Susan Scott

WHEN Sherman’s Lagoon first appeared in the Star-Bulletin, the editor responsible for the comics page said to me, “Have you seen Sherman’s Lagoon?”

“I have,” I said.

“And?”

“How can you even ask? You know I love it.”

He smiled. He knew he’d scored a hit.

For those who don’t follow the intellectual section of the paper, Sherman is a sensitive fish of the ’90s, a lazy, lovable loafer. Sherman also happens to be a great white shark.

A great white with feelings? Well, why not?

I’ve never known a great white shark in real life, but I once knew, vaguely, a robust 15-foot tiger shark.

The opportunity came one day while I was riding in a slow-moving Boston whaler in a pristine Hawaii lagoon.

We spotted the dark, meandering shape and decided to take a look.

It was scary, and perhaps foolish, but irresistible.

I was the first to don mask and snorkel, then lean far over the side of the boat.

I clutched the rail for dear life while my companion nearly choked me to death gripping the neck of my T-shirt.

As the boat pulled alongside the shark, I dipped my face in the water.

I’ll always remember that moment.

The shark, so curious as to what was going on, that he looked almost puzzled, watched me as intently as I him.

The animal’s eye moved up, down, forward and back, checking me out. He seemed actually friendly.

In fact, for a tiger shark, he was downright gracious.

He stuck around long enough for each of the three of us to get a good look. Then, tiring of our silly game (and likely our silly faces), he took off.

Sherman reminds me of that shark and that moment. It’s a fond memory.

Still, neither Sherman nor his girlfriend Megan ranks as my favorite lagoon animal.

That honor goes to their buddy Fillmore, the sea turtle who wears jockey shorts under his shell and is perpetually searching for love.

This isn’t far from real life where love for a male sea turtle often means frustration.

I have heard of male sea turtles trying to mate with crude decoys, divers, other males and even rowboats.

The one time I saw a pair of sea turtles mating, they were on a beach. Since sea turtles always mate in the water, it was likely the tide had gone out on this pair and they simply hadn’t noticed.

I watched them for a long time, maybe an hour. This isn’t as interesting as it sounds because neither turtle moved a muscle the entire time.

Finally, the male slid off the female, then lay dreamily on the sand, completely oblivious of the gawking humans.

I keep hoping Fillmore will find such a willing girlfriend and have an equally fulfilling experience.

Also living in Sherman’s lagoon is Hawthorne, a hermit crab who has adopted a beer can for his shell.

I’ve never seen a real hermit crab in a beer can, but I did see one once in a Styrofoam cup.

I was walking though a jungle-edged beach on a South Pacific island when this battered white cup got up and started running.

I followed, stumbling over roots and through wet leaves.

When I finally cornered this cup-with-legs, it turned on me, showing its true self: a plucky, but terrified, hermit crab.

The crab raised its pincers in an admirable show of force. I felt bad that I had frightened it so. I named it Hawthorne and left it alone.

Sherman’s Lagoon provides an amusing look at the marine world I enjoy so much. In real life, that world is just as much fun.


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

 

Hydroids look beautiful but pack a painful sting

Published June 3, 1996 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1996 Susan Scott

DURING a recent dive, my partner motioned for me to look at something he found. I squinted into the dark crack where he was pointing. What is that moving around back there? I wondered. Shrimp? I leaned closer. Yes. Here was a group of odd but charming shrimp, a species I hadn’t seen before.

I leaned into the cave to get a better look, but my giant, bubbling face alarmed the little creatures. They moved toward the back of their shelter.

Determined to see them better, I adjusted my grip to push myself forward. Then . . . Ouch! A sharp pain on the underside of my right wrist made me jerk my arm up. I looked down. My hand had been resting near what looked like a lovely bouquet of white feathers. But the angelic appearance of these plumes didn’t trick me. I knew I had just received my first hydroid sting.

Hydroids look like delicate seaweeds, but they are actually animals, closely related to corals, jellyfish, sea anemones and Portuguese man-of-war.

At least 28 species of hydroids, most standing only a few inches tall, inhabit the shallow waters of the main Hawaiian Islands. They are also common along coastlines nearly everywhere else in the world. Rocks, boat bottoms, and piers often bear colonies of these delicate creatures.

The dainty appearance of these animals is deceiving. Hydroids are carnivores, using their nematocyst-laden feeding tentacles, positioned along their “branches”, to sting and catch passing shrimp, worms and animal plankton.

These stinging nematocysts also discharge venom into human skin upon contact. Hydroid stings are fairly common among people who clean fouled boat bottoms. Also, scuba divers sometimes get hydroid stings by accidentally brushing up against a colony, like I did during the shrimp incident.

Hydroids can cause other trouble. In 1955, pieces of hydroid colonies were dislodged from rocks during construction of a pier in Hilo Harbor. Project workers, who often were standing in the water, were plagued by these drifting remnants that got caught under their clothing.

Most hydroid stings almost immediately produce small red bumps that remain itchy and painful for hours. Sometime victims feel a prickly sensation. This rash can last up to 10 days. Skin with hair on it usually has less reaction than bare skin. More-severe sting reactions are blisters, swelling and hives.

No cure exists. Rinse the sting with water, (salt or fresh), to wash away any adhering nematocysts, then apply ice for pain. For persistent itching or skin rash, try 1 percent hydrocortisone ointment four times a day, and one or two 25 milligram diphenhydramine (Benadryl) tablets every six hours. Diphenhydramine may cause drowsiness so don’t drive, swim or surf after taking this medication. Both these drugs are sold without prescription.

If the rash worsens, allergic symptoms occur, or a feeling of generalized illness develops, see a doctor immediately.

I didn’t do anything to my hydroid sting except take a shower after the dive. My wrist burned for an hour or so, then became a minor rash, disappearing in about a week.

The discomfort was worth it. I got a great look at those shrimp.


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