Tag Archives: hagfish

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.

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.

Slimy, blind hagfish work to keep ocean floor clean

Published November 16, 1998 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1998 Susan Scott

YEARS ago, when I first moved to Hawaii, I was obsessed with reef fish. I wanted to know everything about these otherworldly creatures – their names, what they eat, how they reproduce . . . there was no end to the questions I had about Hawaii’s marvelous marine fish.

I bought some popular fish books, but they weren’t enough. Soon I enrolled in an ichthyology course at the University of Hawaii.

It was my first class there and I couldn’t wait to begin. I looked forward to learning some serious local marine biology.

Imagine my disappointment when the professor started the semester by teaching about one of his personal favorites, the hagfish.

For those who never heard of hagfish, here’s a clue to my dismay: These fishes’ other common name is slime hag and their scientific name means mucus.

The names are appropriate because hagfish are masters at creating slime. One adult can turn a two-gallon bucket of water into a thick, gooey gob in just minutes.

Hagfish make this slime with about 200 specialized glands, releasing the stuff in varying amounts, depending upon the circumstances.

When feeding, hagfish produce only a small amount of slime. But when cornered or captured, the fish oozes from all glands at once.

Hagfish slime begins as a small amount of thick white fluid. But the strange excretion absorbs seawater and thus expands several hundred times in size.

The resulting clear goo clogs up the gills of fish predators, either suffocating them or driving them off.

The system works well, except for one minor flaw: The hagfish hates its own slime.

But this is no real problem for a hagfish. To get rid of its own gunk, this 3-foot-long, eel-shaped fish simply ties itself in a knot, then sweeps the knot toward the head, scraping itself clean.

Besides their slime and knot-tying habits, hagfish are also odd in that they are blind, jawless, scaleless and finless. In 1758, a biologist even classified them as worms.

So, what good are these outlandish fish? Slime hags are an asset to the ocean, playing a crucial role in the marine food chain.

These fish live on the ocean floor, eating just about anything they come across, dead or alive. That means they clean up the messes, vacuuming up everything from dead whales to the discarded so-called “bycatch” from commercial trawling fleets.

They are also important food for some octopuses, seabirds, fish, seals and dolphins.

Since hagfish don’t have teeth, they can’t bite through tough whale skin or fish scales. Unless other scavengers have already opened a carcass, hagfish enter through the gills, mouth or anus, then eat from the inside out.

Although hagfish live in Hawaii waters, few of us are likely to ever see one. These fish prefer water cooler than 71 degrees Fahrenheit and therefore stay deep.

In tropical waters, hagfish are usually found at about 1,800 feet or deeper. In the cold waters of South Africa, Chile and New Zealand, hagfish are sometimes seen in tide pools.

Most of us can’t get to the southern hemisphere to see a hagfish, but we can try looking at Ala Moana Shopping Center. The purses, shoes and wallets advertised as eelskin are often made of slime-hag hide.

Like countless other marine fish today, hagfish populations are being drastically reduced as fishermen take them for their skins. No one knows the ultimate result of the decline of this strange and wonderful fish, but likely it isn’t good.

Today, I thank my former professor for teaching me about hagfish and dozens of other fish unknown to me.

I know now that that’s the real reason I was there.