Tag Archives: scorpionfish

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.

With friends amid the reef, snorkeling becomes social

Published January 18, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott
Trumpetfish

A trumpetfish is counted among the regulars living their lives near a beach along Oahu’s North Shore. ©2015 Susan Scott

While working at Midway, Craig and I made a new friend and invited him to stay with us for a couple of days before he went home to Canada. Because Luke loves snorkeling, and so does Craig’s mother, Claire, visiting from Seattle, we went to my favorite North Shore beach and plunged in.

I know the area well and guided our guests to a turtle spa, where we watched damselfish nibble algae off the turtles’ shells and pluck parasites from their skin. In addition to the usual reef fish, we found a scorpionfish, some marbled shrimp and a yellow-margin moray eel hiding under a rock.

It was a great day, we all agreed, and headed for the beach. But Luke wasn’t done. Calling my name, he motioned for me to come look.

I arrived to find a gray, nearly 3-foot-long trumpetfish standing on its head. The sight is always marvelous, but was even more so because I know that fish. The big predator hangs out near the turtle cleaning station pretending to be a stick. When a gullible fish swims close, the trumpetfish inhales it.

You would think the fish in that area might figure out that that’s no stick in the water, but no. The trumpetfish is huge, healthy and nearly always there.

Cornetfish, close cousins of the trumpetfish, also hang out on that reef. (It has a strong horn section.) Both species have long narrow bodies, but with a notable difference.

From above looking down, and also head-on, trumpetfish look so slim, you can totally miss seeing the fish. But view the same fish from the side and it’s several inches tall, the body broad and beefy.

Cornetfish bodies are the reverse: Their backs are wide enough to be obvious from above, but from the side the fish is flat as a plate and nearly invisible. To further fool their prey, both types can change colors and patterns to blend in with their backgrounds.

Trumpetfish grow about 30 inches long and are like sticks in that they can’t bend their bodies. But cornetfish can. They spring-load their 63-inch-long (maximum length) bodies in an S shape and lunge for their prey.

Trumpetfish and cornetfish are easy to tell apart by their tails. The trumpetfish’s tail is a stubby stalk ending in a fan. The cornetfish’s tail looks like a whip. Both species use the vacuum cleaner method of capture: The fish suck prey into their expandable mouths.

By swimming often in the same place, I recognize some of the undersea locals and consider them friends. As I do 33-year-old Luke and 92-year-old Claire. Snorkeling is a communal ocean sport where neither age nor species matters. What does matter is where you do it.

Scorpionfish can be tough to spot, even inches away

Published April 20, 2015 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2015 Susan Scott
Plover

A scorpionfish matches its surroundings well. ©2015 Susan Scott

The trouble with taking pictures of scorpionfish, called nohu in Hawaiian, is that I often delete the photos thinking I missed whatever fish I was trying to shoot. Then later I wonder what happened to my scorpionfish pictures and find them in the recycle bin.

Not this time. While snorkeling recently, I found a devil scorpionfish sitting right out in the open, exceptionally noticeable in all its bumpy beauty. When I drew close to snap photos, the 12-inch-long fish held its ground. Go ahead, those bulging eyes seemed to say as the fish fanned out its scalloped side fins. Touch me. See what happens.

I knew what would happen. Scorpionfish belong to a large family of fish that get their name from venomous fin spines.

Some scorpionfish match their surroundings so well that they’re hard to spot even when right in front of your face. These types grow algae and fleshy flaps on their skin for camouflage. When this invisibility cloak gets overly fuzzy, the fish molts and starts over.

Other scorpionfish family members, lion fish and turkey fish, use the opposite defense strategy. Their flamboyant colors and conspicuous fins are like big guns warning would-be predators to back off or be sorry.

The two diverse scorpionfish forms are clues to these fishes’ hunting methods. The camouflaged species are ambush predators, lying as motionless as the rocks they mimic while waiting for passing prey. With a lightning-speed lunge, the scorpionfish swallows the unsuspecting fish or invertebrate whole.

Lion fish and turkey fish use their delicate-looking fins to wave sand and debris off creatures on the ocean floor. The fanlike fins also trap prey in corners and against walls of coral and rocky reefs.

The most notorious of all stinging fish are the South Pacific’s stonefishes, but those species belong to a different family not found in Hawaii. Although stings from stonefish cause the rare death, fatalities usually occur in people who have other medical conditions. When supported in modern medical facilities, most people with stonefish stings survive.

Hawaii’s scorpionfish stings won’t kill you, but they hurt like the devil. Immersing the wound in hot water often relieves the pain.

Scorpionfish use their venomous spines for defense only. Leave them alone and they’ll return the favor.

I took several pictures of the little limestone impersonator and back home immediately downloaded my memory card. Even so, when organizing pictures recently, I wondered what I was thinking to have saved a photo file of rocks.


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

©2015 Susan Scott

 

Summer warmth, long days spawn an abundance of fry

fish

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
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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