Monthly Archives: November 1998

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.

 

Hunt for worms entertains with color, speed, mystery

Published November 9, 1998 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1998 Susan Scott

WHEN I was a kid, I loved to play with worms. On rainy days I waited impatiently for night to fall; then I would creep through the back yard hunting for night crawlers. The brown worms were stretched out in the flower beds, all wet and glistening, then WHOMP, I would snatch them up and drop them into a coffee can full of soil.

The next day, I examined my worms for a while, then gave the can to my grandpa, who graciously accepted it for fishing.

I still like to play with worms, only now my back yard is the ocean and the worms are marine.

Last week, near my boat in the Ala Wai Boat Harbor, I noticed a row of tube worms called feather dusters. These build permanent tube homes in the cracks and crevices of rocks and reef. The tubes, made of mucus, sand and bits of shell, are good protection from hungry fish and probing crabs.

But the encased worm must eat. To do so, it extends a feathery bouquet of tentacles in the shape of one or two spiral funnels.

Tiny beating hairs on the tentacles cause water to flow through the “feathers,” where particles of drifting plants, animals and debris get trapped. The beating hairs drive this stuff into grooves on the tentacles and down to the base. There, the worm sorts its catch, rejecting pieces too large to eat, saving pieces suitable for tube building, and eating the rest.

Besides gathering food and construction material, these worms’ tentacles also absorb oxygen.

This water-sifting system works well, but such colorful plumage sticking out in front of every passing predator makes the worm vulnerable. And that’s where the fun comes in.

Feather dusters have what is called a shadow reflex. That means when an object passes over, the worm withdraws its tentacles in a fraction of a second. Therefore, if you wave your hand near a feather duster, or even pass it over the worm, it will instantly haul in its tentacles.

It’s fun to watch a row of feather dusters duck inside their tubes; it’s also fun to wait a minute and watch them peek out again. When left alone, the whole row was out again in just a few minutes.

No one knows exactly how this shadow reflex works. Most feather dusters have eyes, which look like dark spots on the main axis of their feathery tentacles. But when researchers remove these eyes, the worms still retreat rapidly from shadows.

Feather dusters are beautiful – sometimes too beautiful for their own good. Once I saw two men chipping at harbor rocks to get worms to sell to aquarium keepers. When I asked them to stop, they ignored me. Soon the area was sadly bare of the lovely creatures.

But now they’re back. I still play with them, but I spook the creatures only once, then leave them to eat and breathe in peace.

I feel bad now about plucking those night crawlers. But come to think of it, I don’t remember my grandfather going fishing very often. He may have returned the worms to the garden where, like the feather dusters, they continued their job of maintaining a healthy environment.