1 Coelacanth  NYTimes  Apr. 18, 1995 B6


Unless decisive steps are swiftly taken to curb human predation, the coelacanth, a very rare fish once thought  to have accompanied the dinosaurs into extinction, will truly die out, a team of German zoologists reports.

This gloomy assessment by Dr Hans Fricke and his colleagues at the Max Planck Institute for Behavi­oral Physiology in Seewiesen follows their latest annual census of coelacanths living off the coast of Grande Comore, the largest of the islands making up the Federal Is­lamic Republic of Comoros. Along a five mile stretch of coast where the fish concentrate — about one-tenth of the island’s coastline — the coelacanth population remained steady from 19895 to 1991, Dr Fricke reported recently in the journal Nature. But from 1991 through 1994, the aver­age number of coelacanths living in their deep Indian Ocean lava caves fell from 20.5 fish per cave to 6.5.

It is possible, Dr, Fricke says, that this alarming decline is the result of a natural population fluctuation or an emigration of coelacanths away from the survey area, but it seems much likelier that has descended aboard submersibles into the coelacanths’ habi­tat.  Through thick viewing ports, the team photographs, studies and counts the coelacanths in their submarine caves, which, although close to shore, lie at a depth or about 650 feet. Coelacanths are nocturnal ani­mals, hunting at night for bottom-dwelling prey at depths up in 2,300 feet and resting during the day in their caves. Since individual coelacanths have distinctive markings, scientists can identify and track them year after year.

Although a handful of the big fish have been found in waters off the coast of South Africa and elsewhere in the Indian Ocean, the only known community of substantial size lives along the Grande Comore coast.   Dr. Fricke believes there are about 200 coelacanths in this area, barely enough to stave off extinction.

The main problem threatening the survival of the coelacanth (Latime­ria chalumnae) is that it lives in a coastal area heavily fished by Co­morans for other species of fish used as food and sources of oil. Al­though the five-foot coelacanths have little or no commercial value, they occasionally grab the hooks in­tended for other fish and are hauled to the surface. Under a new Comoros conservation law, the landing of coel­acanths is forbidden; so local fisher­men usually kill them and throw them away after retrieving valuable fishhooks from their mouths.

Both European government agen­cies and the Comoran Government have tried to halt the accidental landing of coelacanths.  One measure was the mooring of “fish attrac­tors,’ long, brightly colored plastic streamers, from buoys anchored farther from shore than the coel­acanth habitats. The attractors only lure ordinary fish and apparently do not appeal to coelacanths.

But the attractors were anchored so far from shore that fishermen found it inconvenient to paddle their canoes to the designated area. To rectify this, international agencies helped local fishermen buy outboard motors for their canoes.  But by last December, Dr. Fricke said, most of the motors had broken down and the fishermen were again working the coelacanth zone.

In their Nature paper, the scien­tists from the Max Planck Institute group propose a new approach. They suggest replacing the fish attractors, mooring them close to shore but at a depth well above the coelacanth hab­itat. They also suggest installing a submarine television camera in front of one of the coelacanth caves with continuous live video displayed at an information center to be built for fishermen in one of the local villages.

“Frankly. I doubt at this point that the beast can survive, but we have to try something,” Dr. Fricke said. Coelacanths are members of a very ancient suborder of fishes called crossopterygians, or ‘fringe-finned’ fish. Although fossil crossopterygian fishes are common in sedimentary rock dated between 350 million and 60 million years old, they were long thought to have died out shortly after the end of the Mesozoic era, the age of dinosaurs.  But in 1936, paleontologists were stunned to learn hat fishermen off the coast of South Africa had landed a coel­acanth, which captured world atten­tion as a “living fossil”

Since then about 200 coelacanths have been caught, but none has survived capture for more than a few hours. The fish are almost always injured by fishhooks, and since they have strong jaws armed with dagger sharp teeth, fishermen generally club them to avoid dangerous bites. It is also believed that hauling the fish up from great depths may cause injurious pressure changes in their bodies.

Until last year when the Comoros Government banned the export of coelacanth specimens or tissue, Scientists around the world were supplied with enough carcass material to study these fish extensively. Some scientists believe that modern coel­acanths, which have fins below their bodies somewhat resembling legs in shape and movement, are close rela­tives of the line of fishes that gave rise to the first vertebrates to walk on land. This would mean that the ancestors of modern coelacanths were also the ancestors of human beings.

Another group of scientists believe, however, that land terapods (four-legged creatures) descended from a very different line, the lungfish. 

Whatever the case, naturalists, biologists and paleontologists agree that every effort should be made to save the only species of crossopterygian known in have survived to the present day, the coelacanth.

“Everybody feels sorry about extinctions,” Dr. Fricke said. “But they have become so common a lot of us just don’t pay much attention anymore. The coelacanth is something special, however.  It’s a remarkable fish, a window into the distant past and a treasure of nature. If we let him die out it will be a tragedy”



II Fishy Sex-Uncovering the Wild Ways of Fish by Tina Adler



The public has had an unusual num­ber of sex stories to mull over of late. Scarcely a week goes by without a report of another politician’s scandalous sexual foray or a gossip column piece on some stars in vitro fertilization.

But for science buffs with an appetite for bizarre sex yarns, new findings on the antics of fish may prove more satisfying.

For starters, that grouper you dined on at the beach this summer had probably undergone a complete sex change. What’s more, studies suggest that a few species of fish living In and around coral reefs reverse gender as many as 10 times. Some species have two kinds of males—the family man and the run-around. Yet others, such as the common bluehead wrasse, reverse sex , and have two very different types of males.

Why this prurient interest in piscine sex? Scientists hope that investigating what goes on in the brains and bodies of these mutable creatures may help uncover some of the mysteries of human sexuality.

Sex-changing fish are known as successive hermaphrodites—each fish can make either testes or ovaries and produce either eggs or sperm. The simulta­neous hermaphrodite, however, comes equipped with both testes and ovaries. These fish would have to check both the male and female boxes on a personal questionnaire.

One species of sea bass, Serrunus torru­garum, releases eggs during about half of Its 14 or so daily spawns and contributes sperm for the other half. It can switch from providing sperm to releasing eggs within 30 seconds.

S. torru­garum develops more female gonadal tissue as it grows bigger, causing it to release more eggs and fewer sperm. The fish’s spawning behavior remains the same, however. lts increased  egg production may boost reproductive success, since almost all eggs get fertilized but not all sperm find eggs

Other simultaneous hermaphrodites develop more male tissue as they grow. These fish eventually change sex completely, however, becoming successive hermaphrodites. Scientists have studied more than 100 species of successive hermaphrodites but suspect that many more exist.  Most of the species found so far reside in shallow ocean waters.

In the most common type of sex rever­sal, females mature, reproduce, and then become males. Their ovaries disappear entirely (or almost entirely, they grow testes, and their hormonal systems switch. Many fish also change color. They act like males, which in some species includes protecting their nests, behaving aggressively, and courting females. Less commonly, some species change from male to female.

Either way, sex reversal is a very dra­matic change in almost all aspects of the life of the fish.

Most fish undertake the change only once. For many species. It occurs in response to an altered

social environment, as when a dominant male dies or leaves his social group and one of the females becomes male and takes his place. Changing sex can take as little as 4 days. What keeps fish from doing it more often remains unclear. Some researchers suggest that the dominant male’s aggression inhibits sex change in subordinates. Others argue that it’s much more complicated than that.

Some females, for example, won’t become male if their group includes few­er than two to five other females. The benefits of changing sex may not outweigh the costs when so few females exist for males to mate with.

If, as ecologists think, a fish’s primary goal is to reproduce as often as possible, then becoming a male makes a lot of sense. Females often outnumber males, so males get a good rate of return on their mating efforts.

But becoming a female has benefits too. Anemone fish live in small groups. Only the largest female and male reproduce and the female outweighs the male. If this female dies or leaves, her mate becomes a female the largest juvenile fish in the group becomes male and mates with the new female Douglas Shapiro at EMU explains in The Differences Between the Sexes (1994, Cambridge U Press.)

Despite its advantages, acquiring a new sexual identity takes a toll on fish. During the process. they cant repro­duce, yet they probably expend a lot of energy and don't defend themselves well..

Some fish dont stop with one sex change. Scientists have identified at least three species of reefdwelling fish that change sex several times: Paragobiodon echinocepfiahss, Cir­rhauchzhss auit-us. and Tnnrnru okincuuxse.

No doubt other fish perform the same trick. However, scientists know of no other vertebrate that undergoes multiple sex changes. Only one other vertebrate, an African frog, can reverse its gender.

 Earlier laboratory studies revealed that the female T okinwae, a tiny Japanese goby, becomes male in response to the departure of a dominant male. But such males revert back to female when a larger male comes on the scene. The frequency of gender changes depends on the stability of the social system.

The researchers wondered whether all these adjustments left the fish behaving and looking different from female males or females. In a new study it was found that fish going for round two as a male or a female look just like fish that have never entered the ring.

Two scientists, Grober and Sunobe induced females to become males, males to become females, and females to become male and then female again—all by swapping their com­panions. The fish completed a single gender change its as few as 4 days. Unlike many other sex-changing species, T. oki­nauiae always carry with them a remnant of the opposite sex’s gonad.

“The {gonad} cells are already there (and) can probably generate rapid changes in hormones.” Grober specu­lates. Scientists don’t know whether the other two fish that reverse their sex more than once retain such cells.

In just those few days, the fish’s gonads, genital papilia (a flap of skin sensitive to steroid hormones), brain cells, and oth­er anatomical parts changed. The fish’s sex hormones adjusted, the authors assume, but they are only now exam­ining them.

The scientists knew that the number and size of cells that produce peptldes important to reproduction differ in male and female bluehead wrasse, one-time sex reversals. So they examined cells in T oknawae that produce arginine vaso­tocin (AVT) neuropeptides, which regu­late reproductive behavior in many ver­tebrates, to see whether they changed.

The cells enlarged when males became females and shrank when females be­came males. When these males went back to being females, the cells enlarged again, Grober and Sunobe find. The total number of cells didn’t vary

Behavior also served as a good indica­tor of the fishs current sexual status, Grober says. Males, even those new to the job, behaved aggressively, defended their nests and performed a traditional courtship dance.

A trained eye couldn’t miss the differ­ences between the males and the females, he contends. it’s like walking into a singles bar. Is there any issue as to who is a male and who is a female? Absolutely not.”

Sometimes, there a even a clear dis­tinction between the males.  Take the saddleback wrasse, Thaksssoma duperrey. Like salmon and many other species, it has two types of males. They vary in size and take  very different approaches to life, including mating.

Grober and his colleagues are finding clear differences in their brains is well. In one section of the brain, the larger male has many more cells that produce AVT than the smaller males or females do.  

Among vertebrates, almost no other animals except certain fish species have two distinct classes of males, and no ver­tebrates are known to have two types of females, says Andrew H. Bass of Cornell University.

Over the years, Bass has compiled a detailed picture of the two versions of male midshipman fish living off the West Coast of the United States. He presented his most recent findings at the Interna­tional Ethological Conference held in Honolulu in August.

The type I male midshipman takes longer to mature, which gives him time to grow bigger and develop a stronger vocal system for courting. Type II males put their energy into becoming sexually mature and developing their gonads, which make up 9 percent of their body weight. Type I males’ gonads account for a mere 1 percent of their weight. The two males also have different types of testos­terone, Bass explains.

Type I fish build and guard their nests, activities type II males never bother with. The nest builders also hum to attract females and grunt in defense of their home. Type II fellows avoid the courtship, trying instead to invade their neighbors nests to mate with the females.

Midshipman males may resemble comical stereotypes of some human males, but marine scien­tists say that fish and people actually have enough in common to make the study of fish worthwhile.

Research on fish may shed light on how environment and stress inhibit human reproduction and on the role of the brain in human sexual orientation, scientists say. Fish also emphasize the inflexible nature of most other verte­brates’ sexuality, Grober says.

“The speed of (sex changes in fish}the diversity of body systems involved, and their reversibility are remarkable, relative to the rigid nature of these char­acteristics in most vertebrates,” Grober and Sunobe contend.

All of this sexual variation and gender gymnastics helps fish to reproduce more successfully, scientists suspect. But maybe another benefit exists. Maybe. having walked in each othe~s shoes. male and female fish get along better.

Would the battle of the sexes never have begun if humans had more fishlike qualities?       


OCTOBER21. 1995






III  White Sharks can Jump

By Elia, J. Swift

Surfer Magazine

And Other Fun Facts about Your Worst Nightmare

The white shark does not give up its secrets easily.

For decades, scientists have filmed, followed and tagged the sharks; jabbed them with instruments; fed them radio transmitters; and wit­nessed hundreds of attacks. But even scientists who have spent their careers in pursuit of whites say the sharks remain shrouded in the dark­ness of the sea—until they erupt in fearsome violence.

To better understand this elusive predator, 70 of the world’s leading white shark experts gathered this March in Bodega Bay, north of San Francisco, to present their latest research. It was the largest such gath­ering ever held, and the information shared by the scientists is changing our understanding of the white. "I think we can put an end to the mythos that this is a simple beast that just eats, swims and makes babies,’ said Leonard Compagno, director of the Shark Research Center In Cape Town, South Africa. “It Is an animal far more complex than that.’

The white shark, researchers say, is one of the most efficient predators in the world—far more deadly than a land tiger—with a kill ratio of 80 percent or higher per attack. Behavioral studies show whites are sophisticated ‘ambush killers’ who stalk their prey, hiding over dark rock shelves until an animal swims by. Often they will kill seals and let them drift away from rookeries before eating them—in pri­vate, so to speak—so as not to alarm other seals. Unlike most of their cousins, whites are daytime predators, whose eyes are among the most highly developed ever found in sharks.

They are not fat, slow fish, as some have speculated, but are extremely fast on the attack and able to ‘rocket’ through the water. Scientists have seen them chase down uninjured sea lions in pursuits more than 100 yards long.

The more that is known about the white, the more fascinating it becomes.  But what is not known is as impressive as what is known.

Scientists at the conference offered detailed maps of the shark’s brain, ner­vous system and body, plus extraordinarily complex mathematical equations to esti­mate populations, behavior, growth rates and appetites. They argued for hours over the significance of one shark splashing water on another, debated at length about the effects of sun, moon and tides on pre­dation. They showed endless hours of pho­tos and slow-motion films of whites attack­ing—after three days, enough to make any surfer seriously queasy.

But although experts from all of the major white-shark regions—the U.S., Australia, Africa, Europe, South America and Japan—were there, no one could offer more than guesses on some of the most basic questions about the animal. For instance, none of the scientists could say with certainty just now many whites there are in any given area. Guesses range from colonies in the tens off California to pockets of a few hun­dred scattered around the world. No one has seen a white shark mate or give birth, and until 1987, a pregnant female had never been caught for study. Nor can scientists say with certainty where whites travel, if they are nomadic, how long they live, or how big they get. The largest documented white is about 21 feet long, although fishermen off Malta claimed to have landed a 24-footer weighing 6.000 pounds.

One thing is certain: No other sea ani­mals prey upon a full-grown great white. Whites do die of unnatural causes. Aside from getting caught In fishing nets and hunted by men, they seem to have a propensity for choking to death by eating too large a chunk, at least judging from several choked whites that have washed ashore in Northern California.

Some questions about the white’s reproductive pattern have been answered in recent years, but the picture they paint only serves to make the shark scarier than ever. According to Harold Pratt, a federal fisheries biologist from Rhode Island, white sharks have extremely rough sex. Pratt said the male bites and grasps the female's fins before unfurling a '’rather robust clasper”,to fertilize the eggs. As the embryos develop, one of the first distinguishable features is a set of tiny jaws and teeth.  Pratt said the fetuses swim around the womb, resembling a “huge set of teeth with a yoke sac attached.”

The first pregnant female was found in 1987 by Japanese researchers who recovered a l7-foot white that had drowned in a fishing net. Inside the female they discovered 10 full-term, 4-foot long embryos—the first confirmation that whites give live birth. Here’s the eerie part: The babies’ stomachs were filled with tiny teeth, leading some to speculate that the young whites practice inner-uterine cannibalism. In other words, the unborn whites swim in the womb, eating each other until only a handful of the strongest survive.  The white is a predator and hunter even before birth, according to some scientists. (Other scientists at the conference speculated the fish had simply discarded and swallowed teeth as they developed in the womb. Like much in the white shark world, the debate remains unsettled.)

What scientists do know is that off California, the white shark population is expected to increase. The main food source for West Coast whites are marine mammals—sea lions, seals and such. Beginning in 1972, with the passage of the federal Marine Mammal Protection Act, the sea lion population began to explode. It only stands to reason, scien­tists say, that with more food will come more sharks. In fact, we may just now be entering a period unparalleled for whites in the last century. It takes about 14 years for a white to grow large enough to prey on sea mammals—and surfers. That means the corresponding boom in shark population may just be getting started.

“All of the abalone divers agree that the population has grown. They are seeing more every year. .” said Peter Klimiey. a biologist who heads a white shark research project centered on the Farallon Islands, a desolate, windswept and yet beautiful set of islands 25 miles off San Francisco. Since 1985, Klimley and his group have recorded 246 unprovoked attacks by white sharks’ on sea mammals within sight of the island.

What they and other scientists have found is changing some of the myths sur­rounding the shark’s behavior. It was once thought that whites were clumsy killers who often missed their targets. One prominent scientist even suggested were so slow that an Olympic swimmer could give them a race. But the latest research indicates great whites are built for speed, equipped with a tail and muscle structure shared by some of the some of the fastest fish in the sea.


In the Mediterranean, whites have been found with bonito, dolphins and sailfish in their stomachs—animals no one considers slow.. Great whites have incredible acceleration, capable of bursts of speed that propel them from the bot­tom to the surface in the blink of an eye, enough acceleration to go airborne—and breach completely out of the water.

What that means is you’ll never out­ paddle one, even on a longboard.  Forget it!. But that really doesn’t matter because chances  are you’ll never see it coming.. According to attack profiles, whites are devious killers who use their natural coloring to creep within a few feet of prey that never suspect death is watching end waiting.  The great white stalks Its game much like tiger might by swimming along the edges of the reef, typically near a drop-off, “They sight their prey and then come up from underneath and usually behind with a great explosion.

Unlike many research programs, the Farailon group does not entice the sharks with baited traps or feeding targets. All of the data is based upon natu­ral predation patterns. The attacks were usually announced only by a huge splash and spreading blood slick. “There is usu­ally a thunderous splash up to 5 meters high, and then the sea lion appears not devoured, but with a large bite taken out.” Klimiey said. “In not one case did we see the shark or sea lion before the attack. A large percentage of the seals and sea lions are beheaded.”

Klimley has painstakingly plotted and graphed every attack. His team studies water clarity, weather, temperature, time of day, wind direction, lunar phase and a dozen other factors in hopes the date will reveal patterns of behavior to unlock the secrets of the white. What they found is that wind, air temperature, clear or foggy weather, swell direction, lunar phase and water clarity have no signifi­cant influence.

Other factors were more consistent. “The higher the swells the more attacks there were,” said biologist Peter Pyle, a member of the Farailon group. “Also, If there was a period of higher upwelling (marked by strong winds) the day before, we saw more attacks.”

Typically, the white will slowly swim into an area of game, near rocks or beaches where sea mammals gather, and glide along the edge of a reef—right where surfers like to hang out. The sharks have been known to sit almost motionless among the rocks, their dark skin blending in with the reefs, watching their targets before exploding into an attack.

Its only a matter of time until more surfers are hit,” said Dr. Robert Lea, a biologist with the California Department of Fish and Game who records shark attacks. 1n fact, I can’t believe more people haven’t been hit.”

One reason more surfers haven’t been killed is that whites aren’t particularly interested in people. Statistical studies and field observations indicate whites are regularly in the same area as surfers and divers, but rarely attack.

If whites wanted to feed on surfers, it would be so easy that few people would surf or dive north of Monterey. According to scientists, whites are primarily visual predators, meaning they distinguish their prey by eyesight rather than smell. But they also have an incredible sense of smell, with the largest olfactory orbs— smelling glands—ever found in a shark.

Leo Demski, a Florida biologist, has studied the shark’s brain and sensing organs in detail. His findings indicate that out of all the sharks sensory systems, individual smell, hearing, and electroperception, only the visual system appears as well developed.

The eyes of a great white---described by attack survivors as solid black orbs the size of silver dollars, contain a sophisticated array of silvery nerve cords attached to the brain. The nerves are so large that Demski initially assumed they were muscle. Nobody knows how far they can see.

But while the eyes look extraordinary, the brain itse!f is small arid only moder­ately developed compared with other sharks. “It is quite a disappointment for such a star,” Demski said. “Basic­ally, it has a small brain, big nose and warm eyes."

But he would not call the fish dumb. “Being at the top of the food chain, they don’t need the more highly devel­oped nerve clusters other species have developed to avoid predation," -Demskl said.

Despite the painstaking data, hun­dreds of videotapes and scores of sci­entific papers, the great white remains an unpredictable predator. For every dozen attacks that follow a pattern, there is an incident of bizarre behavior creating maddening fluctuations in the statistics. After hitting scores of marine mammals and ignoring other targets in a display of discriminating prey selections, the sharks suddenly will skew the date by eating cardboard boxes, birds, boats and surfers.

“The sharks can discriminate very well. They have amazing sensory abiilty," said Harold Pratt, a federal fisheries biol­ogist from Rhode island. “But they are wild animals, and wild animals are unpre­dictable. You have to realize the white sharks were here first, and when you go into the ocean for an ocean experience, you enter their turf.”


IV  When Fish Bite


Sea Frontiers

Fish have been catching and eating things longer than the swiftest, most terrifying preda­tor that ever roamed the earth. Yet they are such commonplace animals—wherever there’s water you’ll likely find them— that it’s easy to understand why they’re often taken for granted. But to scientists with a passion to learn how earth’s incredible web of life came into being, few organisms that have ever existed come close to offering as rich a field of evolutionary evidence as fish. Florida State University biologist Peter Wainwright is one such scientist whose fasci­nation with the processes of nat­ural selection has led him into a research career that focuses almost entirely on the evolu­tionary history of fishes.

If anything stands out about the 425-million-year-old history of fish. Wainwright says. it’s that the forces of evolution have been stupefyingly creative, Scientists figure there are at least 23.000 species alive today, a figure that easily makes them the most com­mon vertebrate on earth. And among themselves, fish are so con­foundingly varied that fish taxonomists are to be pitied. To complicate matters even more, con­sider nature’s bizarre pack­aging: there are fish with and without jaws: with and without bony skeletons: fish whose entire bodies are encased in rock-hard “boxes:” fish with no teeth and others with fangs. There are fish that look like snakes (eels): like doormats (flounders and rays). like box­cars with fins (whale sharks).

Perhaps not surprisingly, such gaudily diverse morpholo­gy begets a wide range of behavior. Like most wild ani­mals, fish really don’t have much to do in their lives but elude predators.,breed, and eat. But in practicing such basic sur­vival habits, fish demonstrate an astonishing latitude in skill and finicky behavior.

What fish eat has been a matter of supreme interest to humans ever since the invention of the fish hook by Stone Age man.  Given that three quarters of earth’s surface is drowned by their domain, fish have a menu before them like no other living creature. There are vegetarian fish: fish that plow bottom sedi­ments for worms and such: gigantic fish that eat only microscopic plants: fish that can eat fish bigger than they are: parasitic fish who live off their hosts’ good fortune.

A motley bunch of trencher-men to be sure, but how and why fish eat the things they do have been more inter­esting questions among scientists who’ve ever taken a serious look at the way fish feed.

Judging by the collection of  skeletalized fish heads in his office, Wainwnght clearly is among this group. He’s a spe­cialist in piecing together the evolutionary history of feeding behavior in fishes. As arcane as that may sound, such work falls into a classic line of research dating to Darwin, whose evolu­tionary theories sprang from his observations on the eating habits of Galapagos finches. Just as Darwin marvelled at how the size and strength of birds’ beaks neatly match the size and hardness of what they feed on, so have modern fish biologists noted the exquisite symmetry inherent in fishes’ feeding patterns.

“People have always had this intuition that you can figure out what a fish does for its living just by looking at its mouth,” says Wainwright. It’s little won­der that fishes’ heads are by far the most interesting part of their anatomy—they have little option but to use their mouths to do what most animals can do easily with claws, paws, or hands. Seemingly, the animals have tried to make up for being limbless by evolving what clear­ly are the most complex mouth and feeding assem­blages found in the vertebrate world. The task is more complicated because fish live in a medium that is 900 times as dense as air and 80 times as viscous. The result is a morphological tour de force.’ the head of’ an average fish contains as many as two dozen separate bones, and up to three times that many muscles and ligaments, says Wairtwnght.

“Compare that to a typical mammal, such as man, with a head that has only one moving part, the jaw. When fish feed. nearly all of these dozens of parts move in concert.”

Most fish that prey on highly mobile food—such as other fish—rely on speed, cunning, or ingest their food with suck­ing action that can be down­right explosive— with prey literally vanishing in the blink of an eye. Fish accomplish such feats by creating power­ful vacuums inside their mouths, springing them open like hydraulic traps in the pres­ence of food, Wainwright explained.

Since 1993, Wainwright’s work has centered on an odd order called Terraodontiformes. Descended from a line of coral-dwelling species that arose 40 million years ago, modern “tetradonts” have no close rela­tives among living fish. Examples include triggertish, cowfish, puffers, filefish, and the ocean sunfish, Mola mola.

“If ever there was a group of related animals where it’s obvi­ous there’s been a lot of evolu­tionary changes, it’s the tetradonts,” Wainwright says.

     Even a glance at photos of tetradont specimens reveals sharp contrasts in the fishes’ overall looks. Triggerfish., noted for dagger-like dorsal spines and tough, leathery hides, bear considerable likeness to their filefish cousins, but hardly any to cowfish, which get their name from two “horns” protrud­ing from their bony foreheads.  Cowfish.,and their cousin trunk-fish, are akin to swimming rocks, with skins quite literally made of solid bone.

Puffers, and their close cousins, the porcupinefish and the burrfish—both of whom bristle with gristle-like spines— are improbable relatives, too. With perhaps the lone exception of the swell shark, these fish are the only fish capable of expand­ing the size of their bodies, surely among the most creative self-defense mechanisms in all of nature.

     And then there is the sunfish, best represented by the genus Mola. Looking for all the world like earless, swimming heads, these tail-less wonders spend their entire lives wandering the tropical seas, often basking their ponderous bodies—which can weigh up to a ton—at the sur­face. Mid-ocean sailors report­edly have mistaken large speci­mens for submerged life-rafts. Such profound diversity in body shapes within any single group of related animals is extraordinary. The highly variegated tetradont fam­ily tree is rooted by two striking characteristics common to all members, Wainwright says. First, all of them are missing gill covers, flaps of flesh and bone that flank the heads of most fish, practically a stan­dard-issue item in fishdom for protecting the animals’ delicate breathing organs. Tetradonts' gills, on the other hand, are almost entirely concealed by skin or bone, with only a slit or small hole appearing where rows of gills should be.

But it’s the second distinc­tion that intrigues Wainwright. It’s the way tetradonts use their mouths when foraging for food, for eating, and—in the bizarre case of the puffers—for blowing themselves up. When fright­ened, puffers madly gulp water to the point where they could pass for softballs—even basket­balls—with fins. Out of the water, the fish can do the same trick with air, inflating them­selves to comical proportions in an instant.

Almost all fish are noted for their talents at “spitting out” undesirable items (e.g. fish hooks), a behavior Wainwright says is more accurately described as “coughing.” Snail-and other mollusk-munching species are experts at ejecting showers of shell fragments.

Tetradonts are superb “coughers.” says Wainwright, but where some of them really shine is in their abilities to blow water, a specialty which he believes may be unique to the group whose members all have rather small, flute-like mouths imminently suited to the task. Triggerfish. for example, can fire jets of water powerful enough to overturn large sand dollars and even small rocks.

Using an evolutionary histo­ry of the tetradont family worked out by others in the 1970s. Wainwright noted that while all the family members “cough,” as do most fish only the more advanced forms can do much else. For example, “blow­ing” behavior shows up in the triggerfish, a species that appeared sometime after the earlier triplespines. The strange ability to inflate shows up only in the puffers, among the latest arrivals.

The phylogeny clearly sug­gests a link between all behav­iors, but what physiological evi­dence was there to prove it?

First, Wainwright had to establish whether there was anything unusual about how the mouths or heads of various tetradonts are constructed that allow for such remarkable lati­tude in behavior. After a detailed comparison of skeletal and muscular tissue collected from the fishes’ skulls and jaws, he found that in the main, tetradonts share the same skull bones, muscles, and ligaments of most bony fish.

But between species he dis­covered striking differences in how these same parts looked and often how they were linked together. Wainwright not only found wide variation in length, thickness, and definition of muscles, for example, but also in where some of the same mus­cles tied together bones in the head and mouth.

The study turned up no different  parts—just different sizes and shapes  of the same parts, which were often connected to each other in different ways.  Perhaps, then, the fish were using their modified muscles in different ways to take advantage of modified skeletons to pro­duce different “mouth action”— coughing, blowing, inflation.

Perhaps. To answer the ques­tion, Wainwright collected elec­trical impulses recorded directly from the living, muscle-bound heads of the various species while they did all three things. Such delicate work involves implanting fine-wire electrodes in the fishes’ heads and jaws.

Analysis of the data revealed a surprising find: all of the fish were using the same patterns of muscle contraction, whether they were coughing, blowing, or blowing themselves up.

Interestingly, despite having highly diversified capabilities, with exquisite control of their varied muscles. Wainwright realized that the tetradonts were using a pattern of muscle con­traction that apparently gov­erned not only their own curious feeding behavior but that of other, entirely unrelated species.

“Here we were looking at animals possessing great free­dom of movement in their heads, perhaps greater than most fish, and yet they were relying on the same, primitive motor patterns to feed.”

Triggerfish didn’t acquire their spewing talents by evolv­ing different ways to use their jaw muscles—they evolved dif­ferently shaped bones and mus­cles instead. The signal to “blow" sent by the triggerfish's brain to muscles in its mouth is the same signal that might prompt a puffer to inflate.

“When you apply the same muscle contraction patterns to different sets of mouth parts, you get different responses,” Wainwright says. An analogy might be two car engines, both of which run off the same fuel, applied the same way, but with internal parts configured differ­ently. Pressing the accelerator effects both engines, but perfor­mance can—and most likely will be—quite different between the two.

Wainwright had to conclude that for some reason, the forces of evolution left the basic motor functions that dictate how fish eat comparatively untouched.  Instead of changing the way feeding muscles are used, evo­lution has instead had a field day changing how such muscles look, as well as the bones and ligaments associated with them.

Apparently, in trying to make a fish a better feeder or a more successful predator, by tweak­ing the way its nerves stimulate its muscles, evolution hit a dead end, with the neuromuscular system finally reaching a point where it became as effi­cient as it was ever going to get. The path to advances in feeding capa­bility thus lay in radically changing the size and shape of the mouth. Further advances lay in reshaping the entire body and improving the abil­ity to swim.

Wainwright says such a find­ing is surprising, since there’s no apparent reason why evolu­tion shouldn’t be able to crank out brand new motor patterns— neurological codes so funda­mentally stamped into the brain that they amount to involuntary reflexes—to drive new or great­ly remodeled bones and mus­cles. After all, a general trend in evolution is that neurological systems become more complex the farther up the ladder an organism gets.

“But that’s just not the way it works.” says Wainwright. “It’s basically a story of new behav­iors arising from an ancient set of motor patterns.” Wainwright’s research offers yet another commentary on the fun­damental curiosities of evolu­tion. As a dynamic system that literally feeds on change, on occasion evolution finds it pru­dent to quit fidgeting with things and leave them as they are—as though following the handyman’s dictum: “if it ain’t broke.,don’t fix it.”

adapted ,wth permission from Florida State University's Research in Review.


V An Amazon  Adventure--Candiru

 Can their be a fish that is more feared than a shark? The Amazonian fish, the Candiru, will be introduced and explained why the fish is so feared. Three different issues related to the Candiru fish will be explained; its characteristics, its bad habit, and the cures for the incident which the fish causes. 

 The Candiru is a fish that is not widely known, but has interesting characteristics. Also called the Carnero fish, the Candiru is a very small breed of catfish. The fish's length is one to two inches (Topping Family Publishers, World Wide Web) or 40 to 60 millimeters  Mike Hagen, World Wide Web). Only being four to six millimeters wide, (Mike Hagen, World Wide Web ) helps the bad habit the fish has. The Candiru is a parasitic fish which is completely transparent (Topping Family Publishers, World Wide Web), which makes it almost impossible to see. Despite the transparent look of the fish it is very spiny and its bones are very sharp. The fish only lives in the Amazon and Oranoco River in South America (Topping Family Publishers, World Wide Web). The Candiru's size, look and spine strike fear into humans swimming in these Amazonian rivers.

 The Candiru fish does have an odd and painful instinctual habit. However, this habit is completely human insinuated. Blood and urine attract the fish to humans (Mike Hagen, World Wide Web ), so never swim nude in these Amazonian rivers or urinate in the water. If this is done, while the person is urinating, the Candiru will swim up the person's open urethra, man or women. At first, their is a small tickle felt by the person, almost a sexual tickle (Topping Family Publishers, World Wide Web). After the Candiru is in a comfortable position, it raises its spine, stabbing the inner surface of the urethra and causing outrageous pain (Topping Family Publishers and Mike Hagen, World Wide Web). However, that is only the beginning of the problem. Once the spine is lodged into the urethra, the fish will never leave. Women are more likely to have this event happen to them than men because they have a larger opening. However, more cases of this incident have been reported by men than women. This behavior of the Candiru is a very easily avoided. 

 Though this incident causes extreme pain, their are ways to make the pain stop. Unfortunately, they are either amputation of the organ or death (Topping Family Publishers, World Wide Web). However, these are not the only options to cure this incident. If the person is able to afford it, the person may have very expensive surgery to take out or kill the fish. The two plants used to do this are the Xaqua plant and the Buitach Apple  Mike Hagen, World Wide Web). These plants are inserted up the urethra and let alone to do the job at hand. The Buitach Apple kills the fish and dissolves it like an effervescent tablet  Mike Hagen, World Wide Web). If the surgery cannot be performed or afforded, their are always the first two options. 

 In summary, the Candiru Fish's habit of climbing into a urinating urethra shows why is the most feared fish in all the Amazon. Though its characteristics are not like those of the shark or other dangerous fish, this small parasitic catch can cause just as much pain. The cures do exist, but amputation and death are the only quick ways for the pain to stop. These options are probably most often taken because of the intense non-stop pain. So, one might think twice before making vacation plans to the Amazon and Oranoco River to visit a nude beach.   


Hagen, Mike. "Candiru Urethra" ( debunk/animals/candiru_urethra.html) (12/15/96)

 Topping Family Publishers. "Text Bohica Candiru" (http://text_bohica_candiru/fish/fish3./html) (12/15/96)

       by Peter Ambrose (1996)

 Don't Pee In The Pool

 If you happen to be vacationing in South America and decide to go for a swim, take Mom's advice - don't pee in the pool. Especially if the pool is in the Amazon Basin. It is here that "the only vertebrate parasite known to man" is found.  


     The Candiru (Vaudellia cirrhosa)

 This catfish is a member of the Trichomycteridae family, the parasitic catfishes. It is a small, slender fish that is 2.5-6.0cm long and up to 3.5mm thick. Parasitic by nature, it lives on the blood of host animals. It is not particular, it will just as soon snack on human blood as it will its normal meal, fish blood. Don't be fooled by its slender body either. It can expand considerably when gorging itself on its victim's blood. 

 Candiru enter the gill chamber of their host fish and feed on their blood. This is achieved using "its mouth as a sucking apparatus and rasping with the long teeth in the middle part of its upper jaw." This species doesn't limit its diet only to fish, however. They also have a taste for human blood, which is acquired in a most unpleasant way. (Unpleasant for the human bather that is.) The candiru sometimes enters the urogenital openings of human bathers in search of a meal. Especially if the bather happens to urinate while in the water. Hence the above warning - don't pee in the pool. The flow of urine gives the candiru a distinct path to follow to locate its next meal, just as the flow of water leaving a fish's gills does. Protection affords itself only in the form of tight-fitting clothes. Natives are even known to wear coconut shell guards over their private parts to prevent this very unwelcome visitor. 

 Just how unwelcome is it, you may ask. Well, after forcing its way as far inside its chosen crevice as it can (remember how slender they are), it then locks itself in place using spines located on the gill covers. Not only does this cause excrutiating pain, it also may cause massive bleeding leaving you open to infection. But wait - that's not even the worst. You still have to figure out how to remove this intruder. Most often surgery is the only solution. Surgery you know where. Ouch. 

 So next time you are swimming, remember to take Mom's advice...   

     Don't Pee In The Pool! 


from the March 1973 article of Urology, pages 265-267   Candiru: Urinophilic Catfish Its Gift to Urology   John R. Herman, M.D. New York, New York 

 In the early 1900s many strange and florid tales arose in that rich source of extravaganzas, the Amazon River Basin. One of the strangest was the rumor of the existence of a fish that was urinophilic and could swim up the urethra or into the vagina of the unwary native who urinated while bathing in the Amazon. It was said that this fish, known as candiru, was long, thin, and capable of forcing its way into the body's passage-ways following the trail of urine. Once inside it would eat away the mucous membranes and tissues until hemorrhage would kill it or the host. It was also said that even if one caught the fish by the tail, once in the urethra it could not be pulled out because it would spread itself like an umbrella. Indeed, rumors had it that penectomy was preferred to the misery and pain associated with leaving the fish in the urethra! Warthin refers to Professor C.H. Eigenmann who first told him that natives of the Amazon wore coconut shells over their "organs" to prevent this parasite from entering their bodies. 

 (snip)   In 1836 Poeppig, after a long journey through the country, wrote of a plant known as the Xagua. 

 The fresh juice of Xagua is rightfully claimed to be the surest means of killing and getting rid of these two-inch long little fishes which slip into the outer opening of the bodies of careless bathers and bring about the most dreadful accidents. 

 Gudger, of the American Museum of Natural History, heard of these stories and became interested in learning the truth about the candiru. Was it urinophilic, was it a vertebrate parasite of man, and could it really swim up he urethra? After studying many reports, mostly second-hand but also that from an occasional eye-witness, Gudger became certain that there was indeed a fish called candiru that was a blood sucker. This fish or group of fishes are nuisances and are either ecto- or endoparasites of fishes, beasts, or man. He classified them as members of the family Pygidiidae, Vandellia cirrhosa. Modern ichthyologists classify them as Trichomycteridae. The candiru is scaleless and slimy, having a torpedo-like body measuring from 5 to 8 cm. in length and 4 to 6 mm. in diameter (comparable to no. 12 French catheter) It has large firm opercula (gill covers) with bony spinous processes, rasping premaxillary "cat-like" teeth, and a suctorial mouth. Although he found proof that this fish was attracted by the body secretions of man, especially flesh and blood, he was unable to prove urinophilia. He wrote that "evidence as set forth seems strongly to indicate that the Candirus are tropic to urine." 

 Use of "Cod Pieces"   Gudger evaluated reports of penetration of the human urethra, including those of a U.S. Naval surgeon who stated that he had performed surgical procedures on three such patients, doing a suprapubic cystostomy on one to remove the fish. He concluded that the candiru does penetrate the human urethra, offering further circumstantial evidence, such as the various "cod pieces" or penis protectors worn by the men when they entered the infested water of the Amazon. The women also wore pudendal covers for this purpose.   (snip) 

 In 1941 Vinton and Stickler(6) wrote that "there is no doubt that the creatures actually exist." These fishes are known by the "collective name carnero." The authors quote from a letter by Dr. H.H. Rusby, a pharmacognosist, "as to the attacks of carnero on men and women, the records are established. Feather-bed explorers and theoretical researchers have disputed the facts, but the evidence is abundant and confirmed." Their article also gives first-hand accounts of the fish. The authors also seem to feel that reported losses of penes are more likely due to piranha than to surgical intervention for removal of candiru. 

 Treatment Most important to urologists as well as to the unhappy victims is obtaining relief after an attack. Because the fish spreads its gill covers in trying to get oxygen, the sharp spinous processes on the ends of the opercula engage the urethral wall making extraction from the urethra almost impossible or at least most traumatic. The green fruit of the jagua tree, Genipa americana L., is thought to be the only satisfactory remedy. Picked when green the juice of the fruit is drunk as a tea to drive out the fish.   (snip) 

 (discussion about using buitach for dissolving kidney stones, rather than the bones of candiru)   The buitach apple tissue contains large quantities of apparently usable citric acid, thus calcium is dissolved. Amazonians appear to have been aware of this long before the era of modern medicine, providing another example of a folk-remedy having a valid scientific basis.



COELACANTH READINGS  Reading #1                                  Name.................................................pd..........

1.  What is the COELACANTH and why is it considered unique?

2.  What are the two theories for terripods concerning the COELACANTH and lung fish?

3.  What use are COELACANTH?

4.  What might be some reasons  for their population drop?

5.  What has man done to protect them?  Is it working?

6.  Where is the COELACANTH found?

7.  What has happened to their population?

8.  What is the major characteristic in crossopterygians in their skull?

9.  What might the fat deposit dorsal to the abdominal organs represent?

10.  Describe the attachment of the fins.

11.  What did rhipidistians have to survive on land?

12.  To what family do coelacanths belong?

13.  What is the average size of a Coelacanth?

14.  When had coelacanths been thought to have gone extinct?

15.  When did man find a living coelacanth and where?



Fish Reading #2      

1.  How often do some reef fish reverse gender?

2.  What are sex-changing fish known as?

3.  Describe how sea bass (S. tortugarum) spawn?

4.  What is the most common type of sex reversal?

5.  Some fish only change once.  What causes this to occur?

6.  Name 3 species of reef fish that change sex several times?

7.  Do fish change appearance when they go back to the one sex each time?

8.  Which fish has two types of males?  How are they different?  What about type I & II?

9.  How can one determine the sex of a the males?

10.  How is this sex reversing a benefit?


Reading 3













When fish bite reading                 name.........................................................................pd...........

1. What acivities do fish partake in?

2. List the menus of fish?

3. What is the symmetry of a fish related to?

4. Who are the tetradants?

5. Who are the tetradonts closest relatives to modern day fish?

6. What characteristics are common to all of these fish?

7.  What is the genus of the sunish...describe this fish?

8. Wha would our term for spitting out a hook called?

9. What types of mouth activities can these fish exhibit?

10.  What different muscle pattern do the fish demonstrate for the different mouth actions?

11.  What part of the triggerfish evolved to use their jaw muscles?

12.  How successful was evolution in bringing about changes in the way the nerves stimulate muscles?

13.  Describe the adaptations of the mouthparts  in these fish  in relation to muscle development and bone development?



5. Ciguatera Poisoning Questions:

____1.In paragraph 4, the idea that seaweeds and the dinoflagellates are mixed up in the water column….is considered  (A) fact  (B) Opinion

____2. The estimated loss of $10 million annualy in the seafood industry is considered (A) Fact   (B) Opinion

Put the following stages of the evolution of toxicity into order.

____3. Only large eels and snappers and groupers are toxic (A) 1st  (B) 2nd (C) 3rd (D) 4th

____4 . Almost all reef fish are toxic (A) 1st  (B) 2nd (C) 3rd (D) 4th

____5. Herbivorous fish become toxic (A) 1st  (B) 2nd (C) 3rd (D) 4th

____6 Carnivorous fish become toxic  (A) 1st  (B) 2nd (C) 3rd (D) 4th

____7.  The main idea of this reading is

(A) Ciguatera can move up the food chain without killing fish but being passed on to other animals.(B) Attempts to grow G. toxicus in the lab have been disappointing because lab-cultured organisms produce less toxin than those in natural surroundings(C) thousands of people living in tropical regions of the world are affected by ciguatera poisoning caused by eating fish.(D)   Symptoms of Ciguatera poisoning may include headache, nausea, vomiting, abdominal cramps, etc., and even death.

6. An Amazon  AdventureCandiru

1. What is the main idea of the “Article”?



2. What scientific principle(s) are illustrated in the “article”?

            a) ____________________________________________________

            b) ____________________________________________________

            c) ____________________________________________________


3. What are 5 facts stated in the “article”?

            a) _____________________________________________________

            b) _____________________________________________________

            c) _____________________________________________________




4. What is the conclusion of the  article”?