Tag Archives: butterflyfish

Some fish enjoy the perks of a committed relationship

Published February 15, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott
Hawaii divers have plenty of opportunities to see synchronized swimming butterflyfish: Of the 25 species of the fish in isle waters, at least a dozen are known to live in pairs. Courtesy Russell Gilbert

Hawaii divers have plenty of opportunities to see synchronized swimming butterflyfish: Of the 25 species of the fish in isle waters, at least a dozen are known to live in pairs. Courtesy Russell Gilbert

Last week I watched two fourspot butterflyfish glide around a coral head so close together they were almost touching. Was this a male and female? I wondered. Whenever I’ve seen two butterflyfish together, I’ve always assumed they were male and female, but to what end? Because butterflyfish release their eggs and sperm into open water, these parents don’t have to feed or protect eggs or offspring.

So with plenty of fish in the sea, as they say, and the kids drifting off before they’re even born, what’s the advantage of lifetime liaisons?

It’s clearly a benefit in some butterflyfish species. The world’s coral reefs host about 130 kinds of butterflyfish. Some hang together in schools; others live solitary lives. But at least 78, or about two-thirds, form pairs.

My idea that butterflyfish couples are male and female is mostly accurate. Researchers haven’t studied each species yet, but they have looked at the behavior of some that live in pairs.

One benefit to being a fish couple is that no romancing is required. Neither male nor female has to waste energy searching for a partner or performing elaborate courtship rituals. In one butterflyfish species, couples swim to the reef’s outer edge to spawn during periods of strong tidal currents. This sweeps the precious sex cells away from the reef’s many plankton eaters. And that’s that. The two go back to eating, while trying to avoid being eaten themselves. It’s here that monogamy has other perks. Butterflyfish have varied diets. Some species eat tiny shrimp and crabs, others prefer plankton and many graze on the soft bodies of live corals. One theory about butterflyfish pairing is that when it comes to finding shrimp and crabs hiding in sand and reef cracks, four eyes are clearly better than two.

Another notion is that because the minuscule animals and corals that certain butterflyfish eat live scattered across large areas of the reef, the fish have to travel far and wide to dine. Such roving prevents a male from creating and guarding a harem. But a monogamous male doesn’t have to. He simply keeps his female with him.

Researchers have also noted that some couples watch each other’s back. While one nibbles, the other functions as lookout, signaling when to flee from an approaching predator.

Of Hawaii’s 25 butterflyfish species, at least 12 live in pairs, giving us snorkelers and divers lots of chances to watch synchronized swimming in fish. It’s a marvelous sight to behold, two bright fish waltzing together in matching outfits of yellow, black and white, with the occasional blue or orange accessory. And that may be another reason some butterflyfish pair up. They love ballroom dancing.

Bright colors and designs give fish a flashy disguise

Published August 25, 2014 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2014 Susan Scott

In 1981 I rented mask, snorkel and fins and, for the first time, gazed upon a coral reef. My impression: Such color! The swirling yellow, green, pink and blue fish looked like an underwater confetti toss.

My awe over the colors of reef fish has never faded. To this day, seeing their gaudy colors displayed in such eye-popping patterns makes me happy to be alive.

But how do the fish survive? In the fish-eat-fish world of the ocean, those colors and designs look like neon signs saying, “EAT HERE!” It seems a miracle that any make it to adulthood.

When it comes to being flashy, the pros have to outweigh the cons.

Although countless colorful reef fish do get eaten, being bright isn’t as dangerous as it looks. Those horizontal stripes, vertical bars, frilly fins and diffuse polka dots break up a fish’s shape so that some predators don’t immediately see it as a fish. This form of camouflage is called disruptive coloration.


Another common countermeasure to reef fishes’ conspicuous attire is the Lone Ranger strategy: They wear a mask. Because a fish’s head and eyes are primary targets for an attack, black bars running across the eyes of many species make a predator unable to tell heads from tails.


To add to the confusion, many reef fish have a false eyespot or two on their back or rear fins. A bite to a fin gives the prey a fighting chance to escape and recover. And it works. It’s common to see a ragged fin on an otherwise healthy fish.

On a reef teeming with hundreds of species, sporting yellow stripes, pink spots or blue-lined fins has a huge advantage: Distinct colors and markings enable fish to find their own kind. Such fellowship is crucial for an individual to romance the right species, join the best school and link up with a successful security team.

Good examples of color and design helping fish get it right are members of the flamboyant butterflyfish family, named for their resemblance to butterfly wings.

Raccoon Butterfly Fish - Courtesy Russell Gilbert

Raccoon Butterfly Fish – Courtesy Russell Gilbert

On the reef, we often see butterflyfish swimming in tight pairs. These are the coral eaters, and the couple is a male and female that stick together year after year. The standout markings of each species help the butterflyfish partner up with the right kind, and then keep track of that partner for mating and guard duty.

Coral-eating butterflyfish don’t wipe out coral colonies because the fish take tiny bites from large territories that the couple defends together. In ousting trespassers from a sprawling estate, two fish are better than one.

Other butterflyfish species graze on tiny animals drifting in the water, settled on the seafloor or stuck to rocks in the form of eggs. These butterflyfish often band together in gangs, all the better to overpower a damselfish dad guarding his eggs or to scout for food in a vast ocean.

That first snorkeling experience I mentioned was in Mexico’s Garrafon Natural Reef Park, a marine preserve that will always be close to my heart. I had a wonderful experience that day, but the sanctuary gave me more than colorful fish: It painted a picture that remains forever bright.


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


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

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

Fascinating anemones, fish are worth a bit of discomfort

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

Vava’u, Tonga, 2006

VAVA’U, Tonga » I know I’m in a good place when I have fin sores on my feet, and the mask grooves in my forehead are nearly permanent features of my face. Even in my sleep I know I’m in a fine place. The anchorages here have been so still that I awake thinking I’m home.

But I’m nowhere near Oahu. Craig and I are sailing our 37-foot ketch Honu in Tonga.

Specifically, we’re exploring Tonga’s Vavau group, a nearly round archipelago in the northern part of this island nation. Vava’u comprises 60 islands, covering an area 16 by 18 miles.

Massive coral reefs protect Vava’u’s islands from the southeast waves. The result is one of the world’s premier sailing grounds, a cluster of calm waterways weaving around sparsely inhabited islets that look like lush flowerpots. Some have powder-white sand beaches on one side and caves in vertical limestone cliffs on another. Most every islet hosts a vibrant coral reef. And that’s why my snorkel gear is wearing holes in my body.

In some places I don’t kick, but float motionless a few feet above the reef. My presence causes commotion when I’m hovering over a pink, yellow, blue or white anemone. Some anemone tentacles are bubblelike; others remind me of gummy worms. These shag carpets of the reef don’t mind my gaze, but their resident anemone fish do. The little fish act as security guards and take the job seriously.

Anemone fish, Anemone with fish in it. Vava’u, Tonga 2014. © Susan Scott

Anemone fish are the poster fish of symbiosis, living among the tentacles of stinging anemones without being harmed. Researchers believe a mucus coating protects the fish from the anemone’s sting.

As payback for a safe haven, the anemone fish drive off butterflyfish, predators that view anemone tentacles as yummy meals.

But the little anemone fish’s defense maneuvers aren’t limited to butterflyfish. If I get my face too close to their home, the tenant fish show me their frowny faces and sometimes fake a charge. “Get back!” the 6-inch-long Chihuahuas of fish seem say to me, a 68-inch-long monster. “Or what?” I think, smiling. Advancing my camera toward the indignant fish sends them deep into the folds of their wiggly security blanket.

Female anemone fish lay eggs near their anemone’s base, and the male guards them vigorously. Once the eggs hatch, the larvae drift as plankton for a week or two, depending on species. (At least a dozen kinds of anemone fish inhabit the Pacific and Indian oceans, all in shades of orange, brown and white.) After developing fins, the baby fish look for an anemone haven.

All members of this group begin life as males. Usually one monogamous pair of anemone fish share an anemone. If a female is removed from a pair, the male left behind turns into a female.

A dominant juvenile on the anemone’s outskirts then matures and becomes the male of the pair.

The pastel anemones and their plucky companions are so abundant here in Vavau’s warm, clear, shallow waters that I’m snorkeling blisters on my feet and furrows on my face. Never before has pain been so much fun.

Banded Sea Snake. Vava'u Tonga, 2014. ©2014 Susan Scott

Banded Sea Snake. Vava’u Tonga, 2014. ©2014 Susan Scott


Vava’u group of islands, Tonga, 2006

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

©2014 Susan Scott


Coloring book educates about Pacific coral reefs

Published September 8, 1997 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1997 Susan Scott

 When the Hawaiian Islands Humpback Whale National Marine Sanctuary was created in Hawaii, some people argued we didn’t need it. “Why add a federal agency to protect that which is already protected?” they asked.

There were several good answers, but one that rang clear was the promise of marine education. Federal dollars, proponents said, would go into much-needed teaching programs about preserving our humpback whales and their habitat, the ocean.

One product of that promise is the Pacific Coral Reef Coloring Book, one of the sanctuary’s responses to 1997 being designated the International Year of the Reef.

This is no run-of-the-mill coloring book: The text, written on the left, explains coral reef biology and ecology in English, Samoan and Hawaiian. The pictures, on the right, were drawn by Hawaii resident Kathleen Orr and have a distinct local flavor.

Here are some facts I learned from this book:

  • The reefs with the most biodiversity (different kinds of plants and animals) are in the far western Pacific and southeast Asia. The farther you go from this rich center, the fewer species you see.

Australia, close to this coral core, has about 2,000 species of fish. American Samoa, farther away, drops to about half that with 1,000 fish species. And Hawaii, thousands of miles away from the coral reef center of the world, has less than 500 kinds of fish.

  • Triton’s trumpet snails (whose shells you see in every souvenir shop from here to India) are great allies of the coral reef, both in life and in death.

In life, one of the trumpet snails’ favorite meals is the crown-of-thorns starfish, a species notorious for eating coral. After death, the trumpets’ enormous shells provide homes for equally enormous hermit crabs. Crabs are scavengers that clean the reef floor of dead plant and animal material.

We can help the reefs by never killing snails for their shells nor buying such shells in shops.

  • Jacks, called ulua in Hawaiian, are often seen on coral reefs. For these strong swimmers, the reef is a hunting ground.

In contrast are butterflyfish, commonly seen on coral reefs. Some species spend their entire lives near a single clump of coral.

The sanctuary has come through with its promise of marine education. Now all we citizens have to do is take advantage of the offer.

To request these free coloring books, call 541-3184 on Oahu, 879-2818 on Maui.