Under The Sea, Sex Is Slimy Business

  • Harboring an effective camouflage with its host gorgonian coral, the pygmy sea horse species was not discovered until it was found in an aquarium.
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    Harboring an effective camouflage with its host gorgonian coral, the pygmy sea horse species was not discovered until it was found in an aquarium.
    Vickie Coker
  • Lobsters will spray urine, like a perfume, to lure potential mates.
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    Lobsters will spray urine, like a perfume, to lure potential mates.
    Doug Perrine
  • Jawfish protect their eggs from predators by hatching them in their mouth.
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    Jawfish protect their eggs from predators by hatching them in their mouth.
    Steven Kovacs
  • A conch sexual encounter involves the male extending a verge to the female. Predators will sometimes feed on a male conch's verge, but the conch has evolved to regenerate its sexual organ.
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    A conch sexual encounter involves the male extending a verge to the female. Predators will sometimes feed on a male conch's verge, but the conch has evolved to regenerate its sexual organ.
    Jerry Corsaut
  • The parrotfish excretes a cocoon of mucus from its mouth that can hide its scent from predators and perform as a warning system for intruding prey.
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    The parrotfish excretes a cocoon of mucus from its mouth that can hide its scent from predators and perform as a warning system for intruding prey.
    Doug Perrine
  • A male squid envelops a female squid with flashing red tentacles during sex.
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    A male squid envelops a female squid with flashing red tentacles during sex.
    Mark Conlin
  • Two hermaphroditic clown nudibranchs mate.
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    Two hermaphroditic clown nudibranchs mate.
    Diane Armstrong
  • The Greenland shark has poisonous flesh and can live up to 200 years.
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    The Greenland shark has poisonous flesh and can live up to 200 years.
    Doug Perrine
  • A Chromodoris annulata deposits a spiral of eggs.
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    A Chromodoris annulata deposits a spiral of eggs.
    Mark Strickland
  • A male octopus has a specialized arm that transfers packets of sperm to its female counterpart.
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    A male octopus has a specialized arm that transfers packets of sperm to its female counterpart.
    Steven Kovacs

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Sex, Drugs, and Sea Slime: The Ocean's Oddest Creatures
Sex, Drugs, and Sea Slime: The Oceans' Oddest Creatures and Why They Matter
By Ellen Prager
Hardcover, 216 pages
University of Chicago Press
List Price: $26

Read An Excerpt

Never threaten a hagfish. And if you do, watch out.

"When it's threatened or in danger or gets injured, it produces — very quickly — huge amounts of slime," says Ellen Prager, a marine scientist and educator. "In fact, they found that in just a few minutes, it can fill up seven buckets full of gooey, slimy gunk."

The hagfish isn't the only underwater inhabitant with unusual tactics for survival. In Sex, Drugs, and Sea Slime: The Oceans' Oddest Creatures and Why They Matter, Prager describes some of the craziest underwater activities that help ocean creatures stay alive, fight predators, find food and reproduce.

Consider The Lobster

There are more than 100 species of lobsters in the ocean, but the one Americans are probably most familiar with is the Maine lobster, a wide-clawed nocturnal creature with a propensity for urinating on potential mates.

"The male lobsters use [urine] aggressively, but the female lobsters shoot it as a Love Potion No. 9," says Prager. "She shoots when she comes up to a den that might have a male in it. She actually seduces him with her pee and instead of clobbering her over the head with his claw, he says, 'Come in, come in' and gets all touchy-feely."

But before the female and male lobsters mate, the female sheds her shell.

"For the female lobster's private parts to become available, she has to molt," says Prager. "And then she becomes acceptable to the male."

Dominant males are routinely seduced into one-off sexual encounters while female lobsters are generally more choosy, says Prager. Females can store a male's sperm for up to three years, using it to fertilize several batches of eggs.

Coral Reefs: The More, The Merrier

Prager has a unique view of marine life because she used to be the chief scientist at an underwater research lab in the Florida Keys. The lab, which sits underneath 60 feet of water, allows scientists to spend hours underwater studying the ocean without worrying about decompression.

Dr. Ellen Prager

Dr. Ellen Prager Rodrigo Varela/University of Chicago Press hide caption

itoggle caption Rodrigo Varela/University of Chicago Press

The warm and relatively shallow water provided a fertile ground for reef-building corals. The organism, which looks like rock, is considered an animal, plant and mineral. It also provides food and shelter for other marine life and can develop into some of the biggest biologic structures on the planet, says Prager. And just how do they build those structures?

Most coral reefs are what scientists refer to as "broadcasters." That means they release either eggs or sperm into the water, where they float to the surface, mix and become fertilized.

"So if you're a coral and you want to mix your eggs with the sperm of another coral of your species, [you must] release [them] at the same time," says Prager. "So coral reefs spawn synchronously throughout the world. All those corals release their eggs and sperm at the same time."

Prager says she's witnessed the synchronized release of eggs and sperm while on night dives.

"It looks like an undersea snowstorm," she says. "The eggs look like little tiny pink balls and they all start floating up. And coral spawn is yummy fish food so worms and other things come to feed on it. It really [makes you think about] how active the ocean is."

Like the hagfish, corals also emit a mucuslike slime — dubbed "coral snot" — when disturbed.

"I will tell you from experience that if you disturb corals through something like drilling, [they] start to exude huge quantities of slime," she says. "You come up just covered in the stuff."

Ellen Prager has written several books about underwater life, including Chasing Science at Sea: Racing Hurricanes, Stalking Sharks and Living Undersea with Ocean Experts and Volcano: Iceland's Inferno and Earth's Most Active Volcanoes. She has worked at the Sea Education Association in Woods Hole, Mass., the University of Miami's Rosenstiel School of Marine and Atmospheric Science, and the National Undersea Research Center in the Bahamas. Prager has a Ph.D. from Louisiana State University and was chairwoman of the Ocean Research and Resources Advisory Panel for the U.S. government.


Interview Highlights

On the volcanic sexual activity of sea sponges

"A lot of the sponges release their sperm into the water. Other sponges will basically suck in that sperm and fertilize their egg. It looks like smoke coming out of the sponges and you look at it and go, 'What the heck is going on?' and they're broadcasting sponge sperm."

On the transgendered parrotfish

"If you have a harem of parrotfish — a group of female parrotfish, let's say — and it has one dominant male. Something happens to the dominant male and it dies. Amazingly, within several weeks, one of those females can change to a male. And, in fact, some of them change to what we call supermales — [and] become big and extremely colorful and aggressive. They then become the dominant male of the other female parrotfish in the harem. I like to say, 'It's not only transgender. It's transgender on-call.' "

On the well-endowed conch

"Turns out that in the conch, they call the penis its verge. The verge has been the thing of limericks and poems. The biologists know all about this. Not only is it exceptionally long, but because the queen conch is this really big snail, the male sidles up to a female on the seafloor and he has to get his verge outside of his shell and around and underneath the female shell. So that's why it's so long. But there's a little problem: When it's outside of his shell, crabs and eels are all too happy to take advantage of his vulnerabilities. Yum, yum, yum. Well, poor conch. But turns out, he loses one [and] he just grows another. He can regenerate his penis."

On why scientists are interested in kissing anglerfish

"The females are small, soft and they swim around trying to catch food. The males are dwarfs and their entire goal in life is to find a female. They swim around looking for the females. When they find them, I call it the 'never-ending kiss.' They bite into them and their lips get fused to the female and they end up living as a parasite on the female providing sperm. Scientists are really interesting in the immune system of anglerfish because the female's body doesn't reject the male."

Excerpt: 'Sex, Drugs, And Sea Slime'

Sex, Drugs, and Sea Slime: The Ocean's Oddest Creatures
Sex, Drugs, and Sea Slime: The Oceans' Oddest Creatures and Why They Matter
By Ellen Prager
Hardcover, 216 pages
University of Chicago Press
List Price: $26

Mega-Slime, Seduction, and Shape-Shifting

Within the citizenry of the sea, there are some organisms whose dull or familiar countenance hides a secret and strange way of life. Such is the case for an eel-like fish with ancient origins, a well-known and highly delectable crustacean, and an organism with impressive powers of regeneration that masquerades as an undersea log. The talent among these three marine creatures — the hagfish, lobster, and sea cucumber — is impressive. The hagfish can produce an inordinate amount of slime and tie itself into a knot. The lobster is equipped with supersoaking blasters that it uses to wield a powerful potion; and when under attack, the sea cucumber has defenses that are the envy of science fiction writers. These three organisms are definitely among the oceans' most fascinating and surprising of residents.

The Hagfish

To know a hagfish, is to love a hagfish — or maybe not. A good friend of mine in Maine (you know who you are) has developed a new type of phobia; she is convinced that upon entering the Gulf of Maine for a leisurely swim, she will be the target of hagfish. I have tried to convince her that as long as she is not dead or nearly so, they should not be a problem, but she remains unconvinced — hagfish have become her worst nightmare and with good reason.

Hagfishes are blind, jawless, scaleless, and finless fishes with a relatively flexible cartilaginous skeleton somewhat like that of sharks and rays. They resemble eels with a flattened oar-like tail, thick, slippery skin, and one singular nostril above their mouths, around which are several stubby, barbed tentacles. Interestingly, they also have four small hearts.

An adult is typically about half a meter (18 inches) long, though they have been known to reach a scary size of 1.4 meters (4.6 feet). Hagfishes live throughout the world's oceans at the bottom, where it is relatively cool. A few species inhabit shallow waters, but most are found deeper, down to at least 5,000 meters (16,400 feet). It is estimated that there are hundreds of thousands of hagfish residing in the deep waters of the Gulf of Maine.

Though jawless, the hagfish is not without teeth or a means to gain access to tender flesh. It has an extendable tongue equipped with two curved rows of sharp, horny teeth that open and close like a book. Just above that, the hagfish has a fang, which is used to snag prey and keep it from wriggling away. Its toothy tongue and hooked grasp are effective for feeding on soft-bodied creatures, such as worms and other small invertebrates, but not so handy when it comes to prey with tougher skin or scales. Hagfishes have, however, discovered another, easier way to gain access to their victims' tasty, tender insides. They go in through open orifices, such as the mouth, gills, or yes, I am sorry to say, the backdoor. Once inside their prey (already or mostly dead, I swear), hagfishes feast on soft flesh, muscles, organs, and guts. Fishermen know this sly tactic all too well because sometimes upon hauling in their catch all they get is a fish-skin bag full of bones and squirming hagfish.

Along with their gruesome propensity to feed on the dead, hagfishes are well known for their slime, lots of slime. If a hagfish, alias slime monster or slime hag, is threatened or injured, it releases mucus from hundreds of glands along its body. In just minutes, one hagfish can fill seven buckets with slime. The glands of the hagfish actually release a thick white fluid containing vesicles of mucus and bundles of thread-like cells. Like balls of string uncoiling, the threads unwrap; they then tangle, combine with the mucus, absorb seawater, and expand into massive amounts of sticky, slimy hagfish goo. Hagfishes use their slime to deter predators and facilitate escape. However, if a hagfish gets caught in its own slime, it can suffocate and endure a most unpleasant fate — death by goo. It has thus evolved a few useful tricks to clear away its own slime. When slime gets up its nose, the hagfish blows it out by sneezing. To free its body of slime, the hagfish wraps its tail around its body and then slides the knot toward its head, scraping itself clear of goo. Its excellent knot-tying skills are also used in feeding to create leverage and improve its flesh-tearing abilities. The hagfish bites onto an irregularity in the skin of its prey and then slides a knot up toward its head, thus enhancing the strength of its pull and ripping power. This process, however, is slow and awkward, so going for the orifices is still a quicker and more efficient means to obtain access to a victim's soft, tasty insides.

Hagfishes spend most of their time at rest hidden within burrows or among rocks at the seafloor. They can also go for long periods of time without feeding. Following the 1989 Loma Prieta earthquake, hagfish at the Moss Landing Marine Lab survived for fourteen weeks without food. They are quick to respond, however, when a meal is at hand and will converge en masse should a bounty of carrion become available at the seafloor, such as a dead whale. Scientists investigating baited traps in the deep sea regularly find them teeming with feeding, writhing hagfish. The hagfishes have excellent olfactory and tactile senses; they readily sniff for and feel out the weak or the dead. Not much to worry about on a leisurely swim, but for me at least, burial at sea is no longer an option. And as for my friend in Maine, she continues to spread the word about the ghoulish hagfish. One of her disciples is a triathlete who competes during the summers in New England when the water is relatively balmy. He regularly dons a wetsuit to ward off not so much the cold, but rather the sneaky hagfish. On a more positive note he says that just knowing that the orifice-seeking creatures are out there makes him swim faster.

Amazingly, there are some organisms in the sea that find hagfishes appetizing — cod and sharks, as well as octopuses, seals, and dolphins make slippery meals of these not-so-lovely fishes. Hagfishes have changed little over the last 330 million years and are thought to be one of the early ancestors of vertebrate animals with a braincase, such as humans. If you thought evolution from primates was hard to swallow, how about having a hagfish in your ancestral lineage?

Love Potion #9

They have been called the cockroaches of the sea, were considered junk food by America's early settlers, and are now the ultimate in fine dining. But rarely are lobsters recognized for the power of their pee, their antisocial behavior, or the growing pains they must regularly endure. Over decades of laboratory and field research, scientists have discovered many fascinating, and in some cases rather bizarre, things about lobsters. And a warning if you choose to read on: the lobster on your plate may never look quite the same or quite as delectable.

There are over one hundred species of lobsters found throughout the world's oceans, including the classic large-clawed American lobster, better known as the Maine lobster. There are also spiny, mud, spear, whip, and the shovel-like slipper varieties. Their hues vary, from the typical greenish-brown to tan or red, to almost a bluish color. Due to rare mutations, the well-known Maine lobster can sometimes be found suited in bright blue, white, or an odd half-and-half coloration. The basic body plan of a lobster goes something like this — an external hard shell or carapace, a head that is fused with the upper torso, two stalked, moveable and compound eyes, a tail fin, and ten legs. What chefs and diners usually call the tail is actually the animal's muscle-laden, segmented abdomen. The lobster's firm abs are well toned from use in fast swimming escapes, as anyone who has tried to catch one knows. They use rapid contractions of their abdominal muscles to flap their tails and sprint away backward. At one time, scientists thought that lobsters were mainly scavengers, but now they are believed to be active foragers, and at times, ambush predators. They use their claws, jaws, and legs for crushing, seizing, slicing, and a bit of dicing. On the menu for lobsters are mollusks, such as mussels, clams, and scallops, as well as sea urchins, worms, and crabs. Some lobsters have also been seen to eat fish or filter feed, straining seawater for coarse particulate material. If dead fish are available, they will eat that too, and they sometimes even eat each other. In fact, lobsters have been known to ingest a lot of things, including pieces of plastic, tea bags, wool, and even a rusty nail. In general, however, adult lobsters seem to have a discriminating palate, with a preference for fresh shellfish, crabs, or sea urchins.

Most lobsters, particularly in relatively shallow water, are night owls, nocturnal foragers. Shortly after sunset they leave the protection of their dens to go on the prowl. When they return, often just before sunrise, they may go into the shelter they left from or seek out the closest available place for protection. For the Caribbean spiny lobster, a good hiding hole is best if it also comes with company. It looks for crevices, overhangs, or coral outcroppings that can provide concealment and protection, and that contain other spiny lobsters. More is better when it comes to warding off predators such as sharks or a grouper, as a wall of waving whip-like spines covered with tiny spikes must deter many a hungry invader. A backdoor for escapes is also handy, and many lobster holes have two entrances or exits. The adult Maine lobster, on the other hand, does not seem so fond of its neighbors and will fight fiercely over dominance and the best shelters.

Of course, for these lobsters the best dens are not just good for protection, they also lead to more mates, more sex, and probably more descendants. What determines a winner in the power struggles of the Maine lobster? In this case, size does matter — claw size that is.

Research suggests that the Maine lobster is typically a combatant, promiscuous creature. Undersea battles establish a hierarchy that allows dominant males to get prime real estate and use it to attract the most mates. Posturing and displays resolve some confrontations, while others end up in a brawl, a boxing match, or a brutal fight to the death. Some lobsters choose to avoid opponents all together and will run away from a fight or make a fast retreat with a few flicks of the tail. Lobsters that do decide to engage begin by sizing each other up, whipping their antennae to and fro to feel and sniff out their opponents. They may then push, shove, and lock claw to claw, in an arm-wrestling test of strength. In battle, sometimes it is the lobster that draws a claw first that wins, like a western-style duel, or they may test each other's nerve with a game of "chicken." In the extreme, claws or other appendages may be torn or ripped from their bodies. Luckily, lobsters can regenerate most of their appendages. If an eye is lost, however, they cannot grow it back, and strangely enough another appendage may grow in its place, such as an oddly located walking leg. And if the need should arise, a lobster can jettison or slice off its own limb, a clever escape tactic, especially if you can grow back the lost appendage. In large tanks, some victorious lobsters have been observed to show mercy on the defeated, while others are not so kind and may mutilate or hack the loser to death. Research has also revealed that in fights, lobsters get really pissed off — literally.

Whether it is as a precursor to battle or in a bit of foreplay, when Maine lobsters meet, pee matters. They are well-equipped and stocked to make good use of their urine. Each lobster has a pair of muscular nozzles located just below its antennae — a twin set of built-in pee-blasters, which are connected to an ample supply of urine that is stored in two bladders also located within its head. To further its pee-shooting range, a lobster can generate water currents with its gills and mouthparts, enabling it to reach a target, such as an opponent's face, some seven body-lengths or about 1.5 meters (5 feet) away. Lobsters actively sniff for undersea "odors" or chemicals by flicking their smaller pair of antennae, or antennules, back and forth. In laboratory studies, the lobster to pee first and with the "sweetest" smelling urine, along with the largest claw, is the most likely to win in battle. Underlying the effects of the lobster's urine are hormones that seem to control aggression and additional chemicals or pheromones that act as this leggy crustacean's version of "Love Potion #9."

When a female Maine lobster approaches a shelter, hot for some action, she not only sniffs for a male's pee, she lets loose a stream of her own. Her urine can render a once brutish male docile and even touchy, feely. Instead of smacking the female over the head with his crushing claw, the seduced male waves his antennae gently over her body as she enters his den. On occasion, a female's love potion may not be fully effective and she may be rejected, especially if she is unprepared to come out of her shell — and not in a metaphorical sense. Before mating, a female lobster molts, whereby she becomes soft, vulnerable, and her relevant private parts are accessible to the male. By doing so, she also conveniently provides her mate with a nutritious postcoital snack, her molted shell. After mating, a female lobster may spend a few days recovering from her molt within the male's shelter. She then simply walks away and a new female lobster will come to call. Dominant males are repeatedly seduced into a continuous series of short-term affairs, while the females seem to choose when and with whom they will mate. The subordinate males, those that do not win battles or get the best lairs, will sometimes get a few of the dominant males' leftovers, but without a large, attractive condo to share, they remain mainly frustrated bachelors on the make.

Female lobsters can store the males' sperm for up to about three years, using it to fertilize several batches of eggs. They may carry tens of thousands of eggs glued under their abdomens for some ten months before hatching occurs. In their larval stages, the young lobsters join the ranks of the plankton for days, weeks or possibly months depending on the species and surrounding conditions. Each baby lobster will go through several developmental stages before growing into its more familiar form and taking to a life at the seafloor. Juvenile lobsters tend to live in shallow, protected coastal habitats until they are large enough to safely roam at greater depths.

For lobsters, molting is an important part of mating, a life-long necessity, and conceptually at least, a painful process. Like other crustaceans, as a lobster grows it must molt to replace its rigid carapace with one that is larger and able to hold a bigger body, sort of like turning in a small compact car for a minivan. Mature lobsters may molt several times a year; juveniles must do it more often because they grow faster than the adults. But they don't simply leap out of one shell and grow another; it is a lengthy, fascinating process, and lobsters spend a good part of their lives undergoing the changes involved. Molting begins with some serious dieting, as a lobster must shed some of its mass. Simultaneously, a new paper-thin exoskeleton starts to form under its shell and its blood is moved from its outer appendages, like the claws, spines, or legs, into its body. Then it is time for a drink, a really big drink. A lobster guzzles water so that its body swells and its old carapace is pushed apart. Essentially, some serious bloating causes the lobster to unzip, unhinge, and literally burst at its seams. Lying on its side, slicked up with some lubricating slime, a lobster then must pull its body, including the antennae, legs, spines, claws, and mouthparts, out from the remains of its old shell. For Maine lobsters, particularly those well endowed in the claw area, the process must be especially difficult and possibly painful. They must pull their large, bloated claws through the slender jointed wrists of the old carapace. Think of trying to squeeze swollen hands through a pair of handcuffs — and they have to do it every time they molt. Once its appendages are through and the last bit of its shell has been shaken off, the newly emerged lobster or "shedder" is a floppy, jellylike creature trying to stand up on wobbly legs with a shell the consistency of thin, wrinkly plastic wrap. It then goes again for the bloat; drinking water to inflate its size even further so that it has room to grow within its new carapace once it has hardened. A lobster typically devours some of its old shell for a megadose of minerals and nutrients.

Shedding can take just several minutes or last for up to half an hour. It is a dangerous time for the lobsters, as they are immobile and defenseless. They may go into seclusion for several days, emerging only after their new shells have begun to harden. The first body parts to stiffen are those most critical to foraging, such as the tips of the walking legs and mouthparts. It can take several months for the lobsters' carapace to harden completely. Maine lobsters molt principally in the relatively warm summer months.

The Caribbean spiny lobster may not have the brutal mêlées or social rankings of the Maine lobster, but they exhibit at least two very curious and unique behaviors. Just after the first autumn storm, in locations such as the Bahamas, Florida, Cuba, the Gulf of Mexico, and Central America, spiny lobsters begin a two-to-three-week trek into deeper, offshore waters. Many marine organisms make lengthy migrations, some much longer than that of the spiny lobster, but few others do it with such style. During their fall trek, thousands of lobsters will traverse the open bottom, marching in an amazing single-file formation known as a queue. They line up head to tail, each lobster closely following the one in front, guided by the touch of its antennae. The movement of the lobsters seems to entice others to leave their shelters and join the crustacean train. Scientists think that a queue is formed to reduce drag, like a professional bicyclist drafting behind the racer ahead. It may also help to prevent predation or aid in orientation while marching. The spiny lobsters are thought to venture into deeper water to avoid the relatively cold temperatures brought on by storms in the fall and winter months. Other lobsters are known to migrate seasonally, between shelters and habitats, but the spiny lobster may be the only one that creates a single-file offshore express. Experiments suggest that lobsters use the Earth's magnetic field as a guide to navigate the open ocean and that chemical signals may lead them to specific home ranges or locations.

The spiny lobster's acute sense of smell also appears to provide it with an exceptional medical diagnostic capability; one that doctors can only dream of. Mark Butler, a professor at Old Dominion University, and Donald Behringer, a research scientist at the University of Florida, discovered that juvenile spiny lobsters will actively shun diseased neighbors. This normally social lobster will avoid dens that harbor lobsters that are infected with a lethal, pathogenic disease, essentially placing them in quarantine. Even more startling is that the juvenile spiny lobsters seem to be able to detect or "smell" the disease before it becomes infectious. Butler suggests that their behavioral change is an adaptation to thwart the spread of a lethal disease, and that it may be the only known example of this sort of "shunning" in the animal kingdom.

Even with their crushing claws, spiny swords, shield-like carapace, and of course, Super Soaker pee blasters, lobsters are not invulnerable to predators. A wide range of creatures find lobsters fine dining, including fishes, sharks, sea turtles, octopuses, and of course, the most feared of all⎯humans. For those of you who like to eat the disgusting gooey green stuff inside a lobster's body, the tomalley, it is the liver and pancreas combined, which acts as a filter and can accumulate pollutants or toxins over time. It is probably best to forgo this rather questionable delicacy.

Shape-Shifters

The humble sea cucumber sits like a log on the ocean floor and may resemble its namesake from the garden or grocery store, but this creature is far from a simple lackadaisical lump; it is endowed with some very special abilities. Sea cucumbers are tube-shaped and come in various colors, such as tan, green, or black, with bumpy, leathery skin, growing to a typical length of about 15 to 25 centimeters (6 to 10 inches). That's the garden-variety sea cucumber. In fact, there are more than a thousand described species, and many of them are more of a nature-gone-wild version of their fruit look-alike. That's right, cucumbers are in fact a fruit, not a vegetable — one never knows what interesting fact will turn up when researching a book! Sea cucumbers may be dressed in psychedelic hues of electric blue, vivid purple, or shocking red, and sport spikes or frills or appear almost furry. The giant red or California sea cucumber is the largest of its kind, reaching a monstrous length of nearly a meter (30 inches). My favorite is the chocolate chip sea cucumber, covered with tan skin folds resembling that of a shar-pei puppy and speckled with black-brown spots. Sea cucumbers are found worldwide, ranging from the deep sea to shallow shores, and can live in mud, in sand, on rocks, or in coral reefs. They attach to the bottom or move about sluggishly on five rows of small tube feet, which are extended or retracted using an internal hydraulic system of seawater.

For sea cucumbers life is all about finding yummy particles of organic matter. Some sea cucumbers filter seawater to acquire these tasty bits; others use mucus-covered tentacles that they raise up or sweep over the seabed. They bring their tentacles into their mouths, lick off the entrapped particles, and then re-release their sticky collectors to gather more food. There are also some slurpers; these sea cucumbers crawl over the seafloor slurping in sand or mud to sift out the organic matter. It is when threatened that the sea cucumber reveals its truly odd nature.

Sea cucumbers are real-life shape-shifters; if predators near they can morph their skin from hard and lumpy into something a bit less appetizing, akin to a gelatinous slime. When danger looms they literally turn to mush! Sea cucumbers have another very effective and rather disgusting means to deter predators: they eviscerate, readily expelling their insides as a decoy or trap. Some sea cucumbers eject a sticky spaghetti of white tubules, while others release their actual internal organs. A predator such as a fish or sea star may become entangled in the slimy mass or be distracted long enough for the sea cucumber to slowly crawl away. Imagine the shock on a mugger's face if on demand you could let loose of your insides. Amazingly, not only does the sea cucumber survive, but in just three to five weeks it also regenerates its internal organs. Unless you like a handful of guts, it is unwise to pick up or harass a sea cucumber. Some sea cucumbers also exude a toxin, which can leave aquarists baffled when they add this seemingly peaceful creature to their tank and a mass mortality ensues.

Relatively recent research has also discovered that in the deep ocean there are strange, translucent sea cucumbers that can swim—well, sort of swim; actually it looks more like flying. They have specialized winglike flaps at the front and/or back (often difficult to distinguish, by the way) and can lift off, swim a ways and then land back on the seafloor. This adaptation is thought to allow them to more efficiently find food in the deep sea, where dining options are often quite limited and may come in periodic windfalls from above.

I queried a group of graduate students studying marine biology at the University of Miami's Rosenstiel School of Marine and Atmospheric Science about what creature they thought was the oceans' most unusual. One young woman responded immediately: her nomination was the pearlfish and its unique, rather bizarre relationship with sea cucumbers.

The pearlfish's association with the sea cucumber hinges on the fact that the sea cucumber breathes through its butt. Water flows in through the "back entrance" and washes over the animal's respiratory organs, wherein oxygen is consumed and carbon dioxide is released. The water then flows back out the way it came in. The tiny pearlfishes have handily evolved the ability to detect the chemical signature of the sea cucumbers' respiratory outflow. This becomes useful for a pearlfish after a night of foraging, when seeking a protective daytime shelter. Like a heat-, I mean butt-, seeking missile, the pearlfish uses its detecting skills to find a sea cucumber and enter via the backdoor. Its hiding spot within the sea cucumber comes with an added benefit; it is already well stocked with provisions. The pearlfish nibbles on its host's respiratory or reproductive organs. Understandably, some sea cucumbers are not willing hosts and will eject their respiratory or digestive organs to deter the sneaky little fishes. One species of sea cucumber goes even further, as it has evolved a deterrent: a backside lined with teeth to fend off the crafty pearlfish.

Why They Matter

Sea cucumbers, hagfishes, and lobsters all play important roles in the ocean ecosystem and have both obvious as well as more subtle connections to our everyday lives. Within the sea's web of life, hagfishes and lobsters play duel roles, as both scavengers and predators. As predators, these animals keep prey populations in check and remove the weak or sick from the gene pool. As consumers, they also transfer energy in the form of carbon (organic material) up through the ocean ecosystem. Lobsters and hagfishes also provide sustenance for the organisms that eat them, such as fishes, sharks, or marine mammals. Sea cucumbers provide nourishment for other organisms as well, including sea turtles, sea stars, some crustaceans, and many fishes.

As scavengers, the lobster, hagfish, and sea cucumber are part of the oceans' cleanup crew. The hagfishes are probably the best of the bunch, providing a rapid and effective means of cleaning up the dead and rotting of the sea, anything from a 100-ton whale to the discards from an industrial fishing ship. In fact, the practice of dumping fishery discards, the unwanted or too small, is believed to have fueled an increase in some hagfish populations. Sea cucumbers tidy up both the water and the sediments. Where filtering sea cucumbers are abundant, they play an especially important role in promoting water clarity and quality. Slurping sea cucumbers strain organic matter from the sediments. Much like earthworms in a garden, sea cucumbers and other creatures that burrow or feed within the sediments of the seafloor also help to keep the bottom aerated and well mixed.

Food

For most of us, lobster certainly sounds more appetizing than a nice plate of hagfish or sliced-up sea cucumber. In Asia, however, people eat both hagfishes and sea cucumbers. Imagine the eel-like hagfish skewered in s-shaped folds and then roasted-slime hag on a stick. Or how about a nice dinner of braised sea cucumber or a side order stir-fried in black pepper sauce? The fermented viscera of sea cucumbers, aka pickled gonads and intestines, is considered a delicacy in Japan. People tell me that sea cucumber is rather plain tasting, and that much like tofu it sucks up the flavor of whatever it is cooked in. One culinary advisor even suggests that no gourmet should go without experiencing the succulent jelly-like texture of a sea cucumber. I have to question such advice on a whole number of levels.

When it comes to more popular seafood, the lobster is a tasty icon. The variety of ways in which it is served seems endless — the classic steamed lobster, the lobster roll, baked, stuffed, on the grill, covered in a rich cream sauce, stir-fried, poached, and now, as a means to make mac and cheese an epicurean delight. Lobsters are sold throughout the world; they can even be shipped directly to your home. It is a must-have for luxury hotels, restaurants, and cruise lines. Lobster meat is also low in fat and cholesterol — it's the butter for dipping that will go to your waistline and block your arteries. But lobster has become more than just a simple food; eating this ocean animal has become synonymous with being able to afford the best and an important part of a cultural, regional culinary experience. No matter how it is cooked or served, lobster is about much more than just food.

The state of Maine accounts for most of the lobster caught in the United States, with landings in 2008 valued at more than three hundred million dollars. A drive along Maine's coast is all that is needed to see the importance of lobster to the region. Images of the clawed crustacean are everywhere, on signs for roadside seafood shacks and fancy restaurants or hotels, decorating windows, doors, and mailboxes. In this area of the world, lobsters are like hot dogs to baseball or chips to salsa; they are the underpinning of tradition, culture, and tourism. People from around the world travel to Maine to partake of lobster pulled fresh from the sea. Thousands of people are employed directly and indirectly by the industry in fishing, processing, marinas, shipping, hotels, souvenir shops, and in restaurants. And here, lobstering is serious business: battles for fishing territory can get ugly, and illegal harvesting is a grave offense. For the fishermen involved it is a way of life that has passed from one generation to the next and which they fiercely protect. I was fortunate enough in 2009 to spend a day out on a lobster boat off the coast of Maine with Tommy, a seventy-eight-year-old fisherman. As he pulled his traps, I was the bander of the lobsters' claws and helped with rebaiting. It was a rainy, rough, windswept day on the seas, which in no way deterred Tommy or his love for the job. I asked what kept him going day in and day out, hauling hundreds of traps each day for so many years. He said it was simple for him and many others like him; it was a love for the sea and a curiosity to see what each trap would reveal. Midway through the day I understood his calling, peering eagerly over the boat's rail as each trap was hauled up. Would there be a fish, crabs, big lobsters, small lobsters, or females with eggs that needed to be thrown back to preserve the population? It was an endlessly fascinating and productive day. Hopefully, lobsters will continue to provide for this ocean-going, ocean-loving way of life, one that so defines and supports coastal Maine.

Human Health

Here's a surprise — hagfishes may prove beneficial to human health. That's right, the hagfish. Scientists are very interested in their primitive immune systems, which have long protected them against infection. It is especially intriguing given the hagfishes' propensity to feed on the dead, which are usually laden with bacteria and other microbes. Researchers have already identified three potent, broad-spectrum antimicrobial compounds in the Atlantic hagfish that might help to explain their ability to ward off microbial diseases. Hagfishes have also been found to get liver cancers and may provide a means to monitor carcinogenic pollutants in the marine environment.

Sea cucumbers are proving useful in biomedical research as well. Scientific studies have shown that a protein found in sea cucumbers may be an effective tool to inhibit the development of the malaria parasite. Other research suggests the use of sea cucumber extracts to fight colon or pancreatic cancer. Though scientifically unproven, compounds from sea cucumbers are also promoted in dietary supplements as a treatment for arthritis. One only has to wonder about how they regenerate their internal organs to ponder what other medical applications sea cucumbers may one day provide.

Rather than eating lobsters, some scientists are using them to learn more about biology and physiology. Researchers are studying their extraordinary ability to sniff out food, rivals, and the opposite sex to improve our understanding of the sense of smell. Investigators are also looking at the optics of the lobsters' eyes and studying their nervous system and how it controls locomotion and other bodily functions.

Other Uses

In Korea, the deslimed skin of hagfishes is used to make "eel skin" products, such as handbags, shoes, wallets, and briefcases. The hagfish's slime may in and of itself prove of value in biotechnology. Researchers are investigating hagfish "slime threads" as analogs to spider silk. Douglas Fudge of the University of Guelph explains, "We're targeting high-performance applications that could replace polymers like Kevlar, but ultimately, we want to replace materials that are taken for granted every day, like polyester, polypropylene, and nylon, with those made from renewable resources." Just think—one day you could be wearing or using biodegradable material made of synthetic hagfish slime. In New Zealand, hagfish slime is also reportedly used by the Maori as a cleaning agent.

The secret lives of the hagfish, lobster, and sea cucumber provide excellent examples of the weird and wild things going on within the sea. These three organisms also illustrate the importance of even the most bizarre creatures in keeping the oceans functioning and healthy. And what creature better than the lobster to demonstrate our long-standing and strong ties with the sea and marine life, though all three animals are showing great promise in biomedical research. The ocean as well as society benefit when the sea is replete with an abundance of slime-touting hagfishes, shape-shifting sea cucumbers, and pee-wielding, seductive lobsters.

Reprinted with permission from Sex, Drugs, and Sea Slime: The Oceans' Oddest Creatures and Why They Matter, by Ellen Prager, published by the University of Chicago Press. Copyright 2011 Ellen Prager. All rights reserved.

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