Category Archives: Fish

Yap’s gentle giants of the reef prove a bit timid, too

Published February 25, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

Manta rays are gentle giants that are plankton feeders, swimming forward with mouths open to sift the water for food. Paddlelike flaps on each side of the mouth direct plankton down the hatch. Courtesy Manta Ray Bay Resort

YAP >> Because I had never been to Yap, only a one-hour flight from Palau where I had been snorkeling, I signed up for a three-day visit here. All I knew about this South Pacific island was that it had been a major World War II battle site and that we would see manta rays.

Not exactly.

During the war, the U.S. military did not consider Japanese-occupied Yap a strategic target. American planes were sent to bomb only island airfields. Yap residents fled to the hills while 120 American pilots and crews, and an unknown (to me) number of Japanese lost their lives in aerial fighting.

My other mistaken vision of Yap was that most people come here to dive on crashed planes. That’s part of some tours but not mine. We three snorkelers joined a boat with two divers from Germany and two from Japan, all hoping to see Yap’s manta rays.

Mantas can live 50 years. At least 50 individuals call Yap home. Resident researchers identify each fish by distinct black markings on their white bellies. Workers at my top-notch hotel, the Manta Ray Bay Resort, have posted photos and names of Yap’s well-known mantas. My favorite name is Dotcom.

These rays routinely come to certain cleaning stations, where wrasses nibble parasites off the huge kite-shaped fish. Biologists think the mantas might also congregate there to socialize, perhaps males and females flirting for a future hookup.

Mantas once had hellish reputations, their enormous sizes and black backs spooking old-time sailors, who called the fish devil rays. Most mantas are about 10 feet wide, but some can grow over 15 feet wide.

Whatever their size, the fish are harmless. Manta rays have long tails like their sting- and eagle-ray cousins with one exception: Manta tails have no stingers. Nor do mantas have teeth. Like whale sharks, these gentle giants are plankton feeders, swimming forward with mouths open to sift the water for food. Paddlelike flaps on each side of the mouth direct plankton down the hatch.

On the two days that our boat dropped us off near the cleaning stations, the mantas chose to skip hanging out there. But we snorkelers weren’t disappointed. The reef was exquisite and included some magnificent manta relatives: white-tip, black-tip and gray reef sharks. Sharks and rays are related in that their bodies contain no bones, just cartilage.

I loved Yap’s super-friendly people, entwined mangrove forests and pristine reefs. It wasn’t what I expected but that’s the beauty of travel. You get to generate your own impressions.

Don’t, though, take my word for it.

Colorful reef habitats offer shelter from a storm

Published February 18, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

Feather stars are related to starfish. Standing a foot tall, they resemble a bouquet of flexible twigs. ©2017 Susan Scott

KOROR, PALAU >> My week in Palau was not what my eight snorkeling companions and I had pictured. Winter is the dry season here, where usually the days are sunny, the water is clear and jumping off the boat is a relief from the tropical heat. But Mother Nature doesn’t care if visitors have only one week to enjoy paradise. An unseasonal storm front moved over Palau and stalled there.

Blustery squalls drove needlelike rain into our faces, preventing the boat from going to reefs exposed to the strong wind and big waves. Not ones to give up, our resourceful guide and driver found two previously unexplored reefs in bays protected from the wind. Because they were surprise discoveries, they were also protected from other tour boats. The areas were ours alone to enjoy.

The first new reef Robin and Matty found we named Oceanic Coral Garden, a place deserving of the name garden. Sponges in brilliant red, yellow, orange and blue squeezed between, and plastered themselves on, a multitude of coral heads.

Sponges look stuck in one place for life, but these filter feeders can walk. When it needs to move to a better food gathering place in the current, a sponge absorbs cells from one side of the body and deposits them on the other.

Sponges’ gradual way of relocating makes snails look like NASCAR racers. But sponge colors, shapes and the fact that they get around at all made sponges a group favorite.

Crinoid Cove is the name we gave our other private place. The peaks and valleys there were of such coral diversity, it looked as if a bunch of patchwork quilts had been draped over tall tables and low chairs. And on top of nearly each rise perched a crinoid, also known as a feather star.

A flamboyant cousin of starfish, a feather star looks like a bouquet of flexible twigs, called arms, standing about a foot tall. On both sides of each twig extend sticky tube feet spaced like the teeth of a comb.

When a piece of animal plankton drifts into a crinoid’s combs, the gluey feet trap it. The animal then covers the gummy meal with slippery mucus and slides it, with beating hairs, down the middle of the arm’s shaft to the central mouth.

Feather stars hang onto their hilltops with rootlike “feet” and are easily knocked off their perch. No worries. A feather star can swim by curling and flapping those twiglike arms and once again be king of the hill.

Crinoids are two-toned, the base of the arms often black with tube feet of green, orange, yellow or white. Not common, feather stars are a sight to behold and along with the sponges were a group favorite.

Bad weather might spoil a trip but for some, but it didn’t for us. Because of the persistent storms, our wonderful Palauan guides found and shared two of their country’s secret gardens.

Next stop: Yap.

Sharp-eyed fish lurks in the sand stalking prey

Published February 4, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

Hawaii is home to two breeds of sandburrowers. This specimen was found hanging out in the waters off Makapuu. ©2017 Susan Scott

Last weekend I made a dozen new friends. One is Ross Lang-ston, an assistant professor of zoology at Windward Community College. The others are his popeyed fish called sandburrowers.

Although they grow to nearly 3 inches long, my sandburrowers are 1 to 2 inches long — and adorable. They look like they’re wearing swim goggles.

I call the fish Ross’ because he studied Hawaii’s two species for a 2004 doctoral thesis at UH, making him the local expert on the little charmers. When he read my recent column on mole crabs, Ross emailed, wondering if I would like to meet some other shallow-water, sand-dwelling creatures. Yes! Ross brought sieves to a Makapuu beach, and we proceeded to scoop sand in 2 feet of water, as if panning for gold. When the pans hit the air, so did the fish.

We transferred the little leapers to a container filled with seawater and an inch of sand. I don’t know exactly how many we collected, because sandburrower is the perfect name for these fish. After diving for cover, they stay there.

Don’t feel bad if you’ve not seen or heard of these remarkable fish. Most of us haven’t, even though they’re plentiful. In one study off Egypt, researchers found approximately five sandburrowers per square foot, making them one of the most numerous fish in the sandy shallow waters of the Red Sea.

At least 16 species of sandburrowers inhabit the waters of the Indian and Pacific Oceans, some shallow, some deep. Hawaii hosts two, called elegant and Cooke’s. Sandburrowers live only about one year.

A sandburrower resides under the sand with only its spherical eyes above the surface. When a tiny planktonic animal drifts by, whomp! The fish nabs it, traveling four times its body length in 0.05 seconds. Watch Ross’ amazing 15-second video at goo.gl/1HF2UJ. The feeding fish look like shooting stars.

Besides lightning speed, sandburrowers have remarkable vision akin to that of chameleons, each eye moving and focusing independently. During a strike, the fish can turn 185 degrees to avoid objects in its way and still get the meal. Researchers in the Red Sea watched 2,000 strikes in slow-motion video. The fish scored 100 percent of the time.

Ross’ studies centered on the little-known reproduction system of these fish and discovered that Hawaii’s sandburrowers begin life as males and become females as they increase in size. Their floating eggs drift as plankton.

My sandburrowers now lurk in a tank in my kitchen counter, where my brine shrimp offerings cause them to explode from their sand beds. Never before have I had so much fun feeding fish I cannot see.

Thank you, Ross, for introducing us fish lovers to another of Hawaii’s marine treasures.

Ugly bottom dweller has its charms, slime and all

Published January 21, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

Susan Scott’s Christmas tree was made of painted hagfish traps, which frequently wash ashore in Hawaii. ©2017 Susan Scott

Hagfish get no respect. And they should. The eel-shaped, bottom-dwelling creatures, averaging 20 inches long, provide humans with food, clothing, wallets, a crackerjack recycling system and snot. Not many fish are so giving.

Hagfish are best known for producing great gobs of clingy mucus that reminds nearly everyone, including workers at Scripps Institute of Oceanography, of snot (goo.gl/VxDz1L).

Hagfishes’ copious slime, however, isn’t just for grossing people out. It frustrates predators. Deepwater videos show that when a shark or grouper bites a hagfish, it secretes a cloud of mucus. Because fish breathe by taking water in the mouth and out the gills, the slime clogs the gills, choking the attacker: goo.gl/Yn9Apt.

Because hagfish are blind, however, they don’t see the shark coming, and it has its teeth in the hagfish’s skin before the slime fills its gills.

But hagfish live inside a bag of loose skin, which attaches to the body in one line down the creature’s back, and in flexible connections to the mucus glands. If shark teeth puncture the skin, they don’t get the muscle beneath. Since hagfish have low blood pressure, skin bites bleed minimally and don’t appear to slow the fish down.

Baggy skin also helps hagfish, using body contortions, to squeeze through openings half the size of its diameter. This is essential because the bottom-dwelling fish wiggle into the eyes, gills and anuses of dead whales, seals and fish, eating from the inside out.

To help push itself into a puka and wipe slime off its body, a hagfish ties itself in a moving knot. If goo fills its one nostril, the fish sneezes.

Hagfish slime could save us from polyester. Its protein threads are strong as spider silk, meaning it might be a natural and renewable alternative to synthetic fibers, such as nylon and spandex, made from petroleum.

The West Coast has an active hagfish fishery. The main marketplace is Korea, where people eat them and use the skin for so-called eel-skin wallets and purses.

You might think you don’t know hagfish traps, but all Hawaii’s beachgoers do. They’re those black plastic cones with frills that come to a point. Fishers fasten these to a hole in a closed, baited bucket. The fish swim in but can’t get out. Endless numbers of these floating traps come loose from their buckets and end up on Hawaii’s beaches.

Hagfish were a frequent topic of discussion at my house recently. We had several guests over the holidays who all wondered what was up with my weird Christmas tree. It’s made of washed and painted hagfish traps.

Nonprofit’s scientific news is a salve for a gloomy world

Published August 27, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott

The Society for Science and the Public, a nonprofit organization dedicated to sharing scientific news, emails me with weekly updates. As I scroll through the headlines, I’m amazed at the scope of human curiosity and people’s creativity in gaining knowledge, from finding exoplanets to editing genes.

I can spend hours at this well-written site, but before I lose myself in the DNA of Darwin’s dogs or how neuroscientists view “Donkey Kong,” I check out the latest in the marine world. One study that caught my attention was about the Taser-packing fish, the electric eel.

Before I even read the study, I wondered how this eel, scientific name Electrophorus electricus, is related to the moray eels we know so well here in Hawaii.

They’re not. The electric eel isn’t an eel at all. It’s a member of a fish family called knifefish, native to South American lakes and rivers.

The 6-foot-long electric eel delivers up to 600 volts to kill its prey. For those of us who’ve been accidentally shocked by a 110-volt household outlet — or worse, the 220 volts used in other countries — 600 volts is a mind-blowing jolt. Evolution made sure that the eel got its meal.

In waters where electric eels go hunting, other fish lie low, staying motionless behind rocks and among plants. Given such hiding, plus the fact that the electric eel’s vision is poor and the rivers are murky, a biologist at Nashville’s Vanderbilt University wondered how the eel finds its prey.

The researcher discovered that as the eel swims it shoots out tiny electric currents that cause a hiding fish’s muscles to twitch. And that’s all it takes. The eel heads toward the twitcher, shocks and eats.

Another fishy headline read, “Female fish have a fail-safe for surprise sperm attacks.” After a female ocellated wrasse (a Mediterranean species) chooses a mate, the couple make their nest. But bachelor wrasses lurk nearby, waiting for the female to lay her eggs. The rascal then dashes in and floods them with sperm. A Yale biologist discovered, however, that the female wrasse’s ovaries coat the eggs with a fluid that favors fast-swimming sperm. Because mated males have speedier sperm, the female’s chosen mate wins the race to the egg.

Sometimes I get so discouraged by the stream of terrible news throughout the world that I wonder whether our species is doomed. But then I get these science emails and life looks much better. T.H. White explained my feeling in a favorite book, “The Once and Future King”:

“‘The best thing for being sad,’ replied Merlin … ‘is to learn something. … Learn why the world wags and what wags it. That is the only thing which the mind can never exhaust, never alienate, never be tortured by, never fear or distrust, and never dream of regretting.’”

For a learning lift, visit www.societyforscience.org.

Little cleaner wrasses offer spa experience to other fish

Published August 20, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott
A cleaner wrass with an island jack customer. ©2016 Susan Scott

A cleaner wrass with an island jack customer. ©2016 Susan Scott

Last week, in about 7 feet of water, I swam over a reef wall and found myself in the middle of a dozen jacks, a new species to me, each bearing yellow, dashiki marks on their sides.

Having a monster in their midst caused the fish to dart up, down and around, but surprisingly they didn’t flee. When I backed off, I saw why. The jacks were waiting for a turn at the spa.

Reef spas are run by narrow, 4-inch-long fish called cleaner wrasses. A variety of fish pick goodies off other fish for food, but only the cleaner wrasse sets up a service station. It’s a one-stop shop for pest removal, wound debridement and massage.

The wrasses work alone, in pairs or in teams up to five. To advertise their business, the little fish bob their neonlike bodies up and down. The front half of the fish’s body is a glowing yellow, and the rear half is purple with lavender edges. A black stripe runs from eye to tail, accentuating the fish’s bright colors.

You can’t tell a male from a female cleaner wrasse by color, but you can tell a juvenile from an adult because young cleaners are nearly all black. The kids get their grown-up colors early on, when they’re only about an inch and a half long. If a cranky adult chases away a little wrasse sporting its new colors, the youngster can change back to black and safely move to a friendlier neighborhood.

When I first learned about cleaner wrasses while studying biology at the University of Hawaii, the fact that Hawaii hosts an endemic species was so emphasized that I thought the little service fish was a Hawaii-only phenomenon. Later, though, I saw similar cleaner wrasses on just about every reef I visited in the tropical Pacific. The Hawaiian cleaner wrasse, it turns out, is only one of five species in the Indian and Pacific oceans. Ours, though, is the prettiest.

Not all fish that visit wrasse cleaning stations have parasites or dead skin that’s bugging them. Researchers believe that the sensation of the wrasses’ fins wiggling against the skin feels good to their clients. Big fish sometimes come just for a back rub.

The jacks I saw lining up for a rubdown are a rather rare species here. Called island jacks, yellowspot trevally or ulua, these silvery fish with yellow side spots usually school in deep water but sometimes come inshore. They grow to about 28 inches.

I’d never before seen a school of island jacks or watched any jack hold perfectly still with mouth and gill covers open while a cleaner wrasse worked it over. That’s why I don’t mind snorkeling in the same seemingly unremarkable places over and over. I never know what I’m going to get, and it’s always an adventure.

Hallucinations from toxin in fish are rare but potent

Published July 23, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott
Bandtail goatfish, or weke pueo (sometimes called weke pahulu), are among the fish that can cause hallucinatory fish poisoning. ©2016 Susan Scott

Bandtail goatfish, or weke pueo (sometimes called weke pahulu), are among the fish that can cause hallucinatory fish poisoning. ©2016 Susan Scott

A Kentucky man emailed that he was doing research on nightmare weke and wondered whether I knew of recent cases here. Because I hadn’t written about this odd illness, also called hallucinatory fish poisoning, for years, I wondered, too.

The term nightmare weke makes it sound as if only goatfish carry this poison. But the rare toxin, origin unknown, is found throughout tropical and temperate waters. Other culprits include convict tangs (manini), chubs (nenue), mullets (ama), coral groupers and rabbitfish (the latter two not found in Hawaii).

In the Mediterranean and eastern Atlantic, the common food fish saupe, or sea bream, has caused hallucinatory fish poisoning. In Arabic the sea bream is known as “the fish that makes dreams.”

Reunion Islanders (Indian Ocean) call a rabbitfish “the fish that inebriates.” Hawaiians named the sometimes hallucinatory bandtail goatfish weke pahulu, meaning “king of ghosts.”

“Ghost” is putting it mildly. The visions that afflict people who eat affected fish are so dreadful, I get the creeps reading about them.

In 1994 a 40-year-old executive ate sea bream in Cannes, France. Severe vomiting that night caused the man to shorten his vacation and drive home. Soon he started hearing animals screaming and stopped when giant insects surrounded the car. After 36 hours in the hospital (with sedation, I hope), the man was fine.

Another Frenchman in 2002 ate sea bream he bought from a fish market. Because he was 90 and feared people would declare him senile, the man suffered terrifying hallucinations of humans screaming and birds shrieking. When the visions disappeared he reported the incident.

These report dates from a poison center in Marseilles show that the toxin is rare in France. It’s rare in Hawaii, too. From 1990 to 2014 the number of cases reported to the Department of Health was 17, the last one in 2011.

The unidentified toxin occurs in both carnivores and algae-eaters, usually in summer. Cooking doesn’t inactivate the poison, which seems to be concentrated in the head. One Hawaii blog offers good advice to mullet and goatfish fishers: “No eat da head.”

In a 1960 medical journal, researchers wrote that information about this syndrome was being suppressed because “Russia was exceedingly interested in nerve drugs such as this.”

I learned that my emailer’s research was not a scientific study as I thought. Rather, he was gathering material for a New York friend making a film about substances in nature that get people high.

You know it’s a crazy world when people consider poisoning themselves and others with a fish.

Report hallucinatory fish poisonings to the state Department of Health. Save the fish for testing.

Hungry trumpetfish sticks close to turtle at dinnertime

Published May 16, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott
A huge trumpetfish rests near the ocean floor, under a turtle that it uses in a kind of symbiosis called commensalism. ©2016Susan Scott

A huge trumpetfish rests near the ocean floor, under a turtle that it uses in a kind of symbiosis called commensalism. ©2016 Susan Scott

While snorkeling last week I thought I saw a remora stuck to the belly of a big turtle.

Remoras are like the family dog standing under the kitchen table waiting for a dropped tidbit, except remoras are lazier. Using the suction cup on top of their heads, remoras, or suckerfish, stick to sharks, dolphins, whales and turtles, getting free food scraps and free rides as well.

The fish swimming closely under the turtle, however, was not a remora, but a huge trumpetfish about 30 inches long. But trumpetfish are not scavengers. They’re ambush predators. In cozying up to the turtle, the trumpetfish was hiding from damselfish nibbling algae and parasites off the turtle’s shell and limbs. When one of the damselfish moved to the side of the turtle, whomp! It was gone, sucked into the trumpetfish’s expanding mouth.

Reef fish eating algae and parasites off turtles is a type of symbiosis called mutualism because both the turtle and the fish mutually benefit. One gets food. The other gets cleaned.

Famous examples of mutualism are cleaner wrasses, 4-inch-long territorial fish dressed in flashy yellow, black and purple stripes. The pattern and colors of these little fish are like neon shop signs advertising the wrasse’s service station.

Fish needing parasite removal or wound debriding come to the site and hold still while the wrasse does its work. Sometimes fish without parasites or wounds visit wrasse cleaners, letting them eat body mucus. This might gain favor with the cleaner wrasse for future visits. Or maybe it just feels good.

Wrasses don’t have a monopoly on the cleaning business. At least 111 fish and dozens of shrimp species eat parasites and tend wounds on fish. In appreciation, barracuda, moray eels, snappers and other predators don’t eat their cleaners.

Still, reef fish should trust no one. A couple of sneakers called saber-toothed blennies mimic the colors and behavior of the cleaner wrasses. When a gullible fish approaches, the blenny sinks its teeth in, getting a chunk of fin or body. The ruse works only on youngsters. Older fish know the con and steer clear of the biting blennies.

My turtle and trumpetfish were engaged not in mutualism, but in another kind of symbiosis, called commensalism. In this relationship, one species benefits (trumpetfish), and the other is neither helped nor harmed (turtle).

Before I left the water, I saw the turtle resting near the bottom, her buddy fish positioned so centrally underneath it looked like the turtle had grown a trumpetfish tail. So cute, those two. I love marine biology more every day.

Extracted teeth tell the tale of a truly extraordinary fish

Published May 9, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott
Parrotfish have protruding beaklike teeth, used to bite off pieces of coral rock to get to the algae growing on the surface, or to scrape live coral heads to get to the corals’ soft bodies. ©2016 Susan Scott

Parrotfish have protruding beaklike teeth, used to bite off pieces of coral rock to get to the algae growing on the surface, or to scrape live coral heads to get to the corals’ soft bodies. ©2016 Susan Scott

While snorkeling I found a big, pink parrotfish head bumping along the sand near the shorebreak. The freshly dead fish had such striking teeth jutting from its mouth, I picked it up for a closer look. When I clutched the rolling head, though, my fingers touched the fish’s pharyngeal mill, a special set of teeth embedded in the throat. I knew about this parrotfish trait but had never seen it. So I took the head home. After two days of bleaching, cutting, boiling, drying and scrubbing my apartment of fish smell, I had the teeth free of flesh for examination. It was well worth the work.

In addition to their rainbow-colored bodies, parrotfish resemble parrots in their protruding beaklike teeth, two massive uppers and two lowers, each pair with a gap in the middle. Parrotfish also talk, sort of, making distinct crunching sounds as they bite off pieces of coral rock. Most species eat rocks to get the algae growing on the surface. Other parrotfish excavate hard sand surfaces to get algae stubble so short it’s unavailable to other plant-eating fish.

Still other parrotfish, two in Hawaii, scrape live coral heads to eat the corals’ soft bodies. These parrotfish leave conspicuous patches in the shape of their teeth.

Whether they eat algae or live coral, parrotfish bite off more than they can chew because the nutrients they need are growing on, or living inside, chunks of solid limestone. And that’s where the pharyngeal mill comes in.

Throat teeth AKA pharyngeal mill. ©2016 Susan Scott

Throat teeth AKA pharyngeal mill. ©2016 Susan Scott

This second set of teeth in the parrotfish’s throat works like a coffee grinder. Molars on plates move back and forth, pulverizing the rocks to bits. As the tiny stones move on, the parrotfish’s digestive system extracts the nutrients, churns the rubble into fine sand and expels the grains through the anus.

In addition to their jaw-dropping beauty, these extraordinary fish change sex as needed, sleep in self-made mucus sleeping bags and play a large role in keeping our reefs healthy. Parrotfish bite marks on living coral open up spaces for other animals to settle and grow. Parrotfish also mow the reef’s lawns and supply much of the sand that houses countless fish and invertebrates.

Spearfishers have killed the good-tasting parrotfish to the point they’re now rare in Hawaii waters outside of protected areas. You can help Hawaii’s parrotfish, and in turn our coral reefs, by not spearing parrotfish or ordering them in restaurants.

Of course, without supporting tissue, my parrotfish teeth fell apart. Still, I treasure them. The little mound of teeth now sits on my shelf as a tribute to a truly remarkable fish.

Parrotfish teeth cleaned: Pharyngeal mill (top three pieces). Mouth teeth (bottom four pieces.) ©2016 Susan Scott

Parrotfish teeth cleaned: Pharyngeal mill (top three pieces). Mouth teeth (bottom four pieces.) ©2016 Susan Scott

Creatures show that gender is neither rigid nor constant

Published May 2, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott
Most anemonefish are born male and change to female as the need arises. This is a Clark’s anemonefish swimming off Palau. ©2016 Susan Scott

Most anemonefish are born male and change to female as the need arises. This is a Clark’s anemonefish swimming off Palau. ©2016 Susan Scott

North Carolina politicians recently passed a law that requires people in public buildings and schools to use the bathroom corresponding to their gender at birth. When an NPR reporter asked the Rev. Alex McFarland, a North Carolina evangelist, why he supports this legislation, he replied, “This is an issue of natural law … and natural law is the recognition that there are males and females.”

Excuse me, but what natural law would that be? It’s certainly not one of Mother Nature’s. Researchers have discovered hundreds of hermaphrodite fish species in at least 20 families, and marine invertebrate hermaphrodites are so numerable, they’re uncountable. Because animals with both testes and ovaries employ them in such a variety of ways, researchers sort hermaphrodites into three categories: those that permanently have both ovaries and testes, those that start life as males and turn into females, and those that go the other way, from female to male. And given nature, each group has variations galore.

How do these dual-sexed animals reproduce? One can barely count the ways. One example is a kind of sea bass with both testes and ovaries, and it stays that way. This fish doesn’t fertilize itself, but when it meets another of its kind, they both go off, releasing sperm half the time and eggs the other half.

Some deep-sea hermaphrodite fish do fertilize themselves. This doesn’t do much for the gene pool, but it’s handy for keeping the species going when a fish can’t find a mate.

Anemonefish have another tactic. They inhabit anemones in groups of one large male, one large female and several small, immature males. Only the two big sexually mature fish lay eggs and shed sperm.

The little anemonefish in the clan are biding their time. When the breeding female dies, her mate turns into a female, and the largest juvenile matures to become the new breeding male. If the male dies, same thing. A lucky juvenile moves on up.

Some fish that change sex can swing both ways. In Japanese reef gobies, a female in a group becomes male if the dominant male leaves. If a larger male joins the group later, the changed fish reverts to her former female form.

Parrotfish, wrasses, hagfish, lizardfish, sharks, scorpionfish and other fish families all have members of various genders, being male, female, both, in-between, and changing as the situation requires. A heading in my fish textbook says, “When the going gets tough, the tough change sex.” The Rev. McFarland’s belief that there’s a dividing line between male and female organisms on our planet is wrong. In nature, of which we humans are a part, gender is anything but clear-cut.