CLOSE

11 Fishy Facts About Coelacanths

There are plenty of fish in the sea, but few are more astounding than the coelacanths—a group that defied extinction and turned the scientific world upside down.

1. COELACANTHS HAVE BEEN AROUND FOR AT LEAST 407 MILLION YEARS.

During the Devonian, which lasted from 416 to 358 million years ago, ferns evolved, trilobites still roamed the oceans, vertebrates took their first steps onto dry land, and fish began to diversify—hence the period's nickname, "the age of fish." The oldest-known coelacanth appeared in present-day Australia during this time, between 407 and 409 million years ago. Like modern coelacanths, the creature belonged to a group known as the sarcopterygians, or “fleshy-limbed vertebrates.” These animals are defined by their bony skeletons and fleshy, muscular fins that bear a striking resemblance to our own limbs. The similarity is no coincidence: By the end of the Devonian, the sarcopterygians would give rise to the first terrestrial vertebrates, which, in turn, begat the amphibians, the reptiles, and—eventually—mammals like us. Indeed, to modern biologists, humans aren’t descended from sarcopterygians, we actually are sarcopterygians.

2. THE WORD COELACANTH MEANS “HOLLOW SPINE.”

It’s a reference to the hollow, rod-like rays that are present in the creatures’ dorsal fins. The term coelacanth is descended from Coelacanthus granulatus, a name that zoologist Louis Agassiz gave to a prehistoric British species in the 1830s. As it happens, Coelacanthus granulatus was the first coelacanth to ever be scientifically described. Since then, over 120 additional species have been found—including those that are still alive today. (More about them later.)

3. THEY ONCE CAME IN ALL SHAPES AND SIZES.

After the Devonian, coelacanths flourished, evolving to fill an array of different niches. Many were slow-moving marine carnivores that must have ambushed passing prey items, but at least one fossil coelacanth was an active, speedy predator. Discovered in 2012, Rebellatrix divaricerca terrorized the seas that covered British Columbia around 250 million years ago. A sleek creature with a forked tail, the fish probably chased down smaller animals over great distances. Another notable species was Megalocoelacanthus, a toothless giant that grew to be 10 feet long. A few coelacanths left the ocean altogether and became freshwater denizens [PDF]. Some of these lake and river fish would have no doubt encountered the occasional dinosaur.

4. BEFORE 1938, IT WAS ASSUMED THAT ALL COELACANTHS WERE EXTINCT.

Coelacanths past and present constitute an entire order of fish—and for a century, paleontologists believed that the whole lot was wiped out in the same extinction that claimed the dinosaurs (birds notwithstanding) some 66 million years ago. But then, just a few days before Christmas in 1938, a trawler on the Indian Ocean caught a strange-looking fish in its nets. That vessel, the Nerine, was captained by Hendrik Goosen, though he took no notice of the odd beast he’d reeled in. The Nerine proceeded as usual to its destination: a fish market in East London, South Africa. Upon docking there, Goosen—as was his custom—called Marjorie Courtenay-Latimer.

Courtenay-Latimer, the curator of a local museum, had befriended the captain, who would always invite her to comb through his latest haul for odd-looking specimens. But on that day in 1938, she nearly turned him down—she had her hands full with a new fossil exhibit. In the end, Courtenay-Latimer decided to drop by anyway, if only to wish the crew a Merry Christmas.

She would later recount that "I picked away the layers of slime to reveal the most beautiful fish I had ever seen. It was 5 feet long, a pale, mauvy blue with faint flecks of whitish spots; it had an iridescent silver-blue-green sheen all over. It was covered in hard scales, and it had four limb-like fins and a strange little puppy dog tail. It was such a beautiful fish—more like a big china ornament—but I didn't know what it was.” Courtenay-Latimer recovered the corpse, stuffed it, and contacted renowned chemist and ichthyologist J.L.B. Smith. Two months later, he confirmed that her mystery fish was, in fact, a modern-day coelacanth. To honor its discoverer, Smith named the creature Latimeria chalumnae.

5. TWO LIVING SPECIES ARE NOW RECOGNIZED.

Latimeria chalumnae is commonly referred to as the West Indian Ocean coelacanth. Capable of reaching over 6 feet in length, this metallic-blue carnivore occupies the waters off of South Africa, Madagascar, Mozambique, and the Comoro Islands. A deep-sea creature by nature, West Indian Ocean coelacanths typically live at depths of around 300-1000 feet, but have been found at 2000 feet beneath the waves. Their hunting sessions mainly occur at night—during the day, the fish retire to undersea caves, where they hang out in groups of up to 16 individuals.

A smaller, brown-colored species called the Indonesian coelacanth (Latimeria menadoensis) came to light during the late 1990s. Relatively little is known about this elusive creature and only a handful of specimens have ever been documented. At present, both Latimeria species may be in trouble. The West Indian Ocean coelacanth is considered critically endangered and its Indonesian relative has been classified as vulnerable by the International Union for Conservation of Nature (IUCN). If both animals should go extinct, the whole coelacanth order will die out with them—this time, for real.

6. COELACANTHS HAVE A CRAZY MOUTH ...

Unlike any other animal that is presently alive, coelacanths have an intracranial joint behind the eyes that splits the skull in two, enabling the entire snout to swing upward when a coelacanth opens its mouth. The joint allows coelacanths to take disproportionately wide bites and, as biologist Hugo Dutel explains in this video, the joint and its corresponding muscles “[enhance] the overall bite force during the capture of prey.” Keep your fingers away from those teeth, folks.

7. ... AND VESTIGIAL LUNGS.

CT scans have shown that the embryos of these fish start growing lungs at an early point in their lengthy gestation period. Over time, however, a coelacanth’s lung development slows, and by the time it becomes an adult, the organs cease to serve any discernible purpose. Also noteworthy is the fact that flexible plates surround the useless lungs in full-grown Latimeria. Some coelacanth fossils exhibit similar structures.

8. FROM TIME TO TIME, THE FISH LIKE TO SWIM NOSE-DOWN.

Fast-forward to 0:55 in the above video and you’ll observe a curious display. On many occasions, wild coelacanths have been seen adopting what’s often described as a “headstand position.” For up to two full minutes, the fish angle themselves downward, holding their snouts perpendicular to the ocean floor. The maneuver’s purpose is a mystery, although some experts think that it may help the animals track their prey.

9. COELACANTHS MIGHT BE MONOGAMISTS.

Although the mechanics of coelacanth reproduction aren’t fully understood, we do know that their eggs are fertilized within the mother’s body. In 2013, a German team analyzed the corpses of two pregnant Latimeria chalumnae. DNA testing revealed that their unborn broods had each been sired by a single father. This revelation really caught the scientists off-guard.

“For both [of our specimens], it was clear that there was only one male involved,” Dr. Kathrin Lampert, a biologist who helped orchestrate the study, told New Scientist. Going into the tests, she and her colleagues fully expected to find that the eggs had been fertilized by many different males. After all, by breeding with several partners, a mother coelacanth could dramatically increase her clutch’s genetic diversity.

“Monogamous mating systems are most commonly found in species where the father provides parental care or where there is no opportunity for polygamy,” Lampert’s team noted in their report. Perhaps, they argue, female coelacanths save valuable energy by limiting themselves to just one mate per breeding season.

10. ADULTS GIVE A WHOLE NEW MEANING TO THE TERM “FAT-HEAD.”

As a coelacanth gets older, its brain tissue grows at a much slower rate than the rest of its body. In a full-grown adult, the brain itself fills less than 1.5 percent of the brain cavity. The remainder of that space is occupied by fat. Juveniles, meanwhile, have proportionately larger thinking organs and less fat in their braincases.

11. A PROMINENT HEMATOLOGIST ONCE WROTE A COELACANTH OPERETTA.

On September 10, 1975, a dead coelacanth that had been sitting in an aquarium at the American Museum of Natural History since 1962 was dissected. The decision to cut it up had been made when a hematologist named Charles Rand of Long Island University expressed an interest in acquiring some spleen samples. Together, Dr. Rand, paleontologist Bobb Schaeffer, and ichthyologists James Atz and C. Lavett Smith took a scalpel to the fish.

A huge surprise lay in wait beneath its skin. Within this deceased sarcopterygian, the astonished scientists found five embryonic coelacanths. These unborn babies revealed that, unlike most fish, the magnificent Latimeria chalumnae gives birth to live young.

Elated by the breakthrough, Rand started waxing poetic—or should we say operatic? With a parodic zeal that would do "Weird Al" Yankovic proud, the musically-inclined hematologist wrote some lyrics for a new operetta titled A Coelacanth’s Lament, or Quintuplets at 50 Fathoms Can Be Fun. His rhymes were set to the melody of various Gilbert and Sullivan songs, including “Tit Willow” from their 1885 comedic masterpiece The Mikado. Fortunately for all of us, the AMNH has been good enough to upload a few of Rand’s verses. Enjoy.

Original image
iStock
arrow
Big Questions
Why Don't We Eat Turkey Tails?
Original image
iStock

Turkey sandwiches. Turkey soup. Roasted turkey. This year, Americans will consume roughly 245 million birds, with 46 million being prepared and presented on Thanksgiving. What we don’t eat will be repurposed into leftovers.

But there’s one part of the turkey that virtually no family will have on their table: the tail.

Despite our country’s obsession with fattening, dissecting, and searing turkeys, we almost inevitably pass up the fat-infused rear portion. According to Michael Carolan, professor of sociology and associate dean for research at the College for Liberal Arts at Colorado State University, that may have something to do with how Americans have traditionally perceived turkeys. Consumption was rare prior to World War II. When the birds were readily available, there was no demand for the tail because it had never been offered in the first place.

"Tails did and do not fit into what has become our culinary fascination with white meat," Carolan tells Mental Floss. "But also from a marketing [and] processor standpoint, if the consumer was just going to throw the tail away, or will not miss it if it was omitted, [suppliers] saw an opportunity to make additional money."

Indeed, the fact that Americans didn't have a taste for tail didn't prevent the poultry industry from moving on. Tails were being routed to Pacific Island consumers in the 1950s. Rich in protein and fat—a turkey tail is really a gland that produces oil used for grooming—suppliers were able to make use of the unwanted portion. And once consumers were exposed to it, they couldn't get enough.

“By 2007,” according to Carolan, “the average Samoan was consuming more than 44 pounds of turkey tails every year.” Perhaps not coincidentally, Samoans also have alarmingly high obesity rates of 75 percent. In an effort to stave off contributing factors, importing tails to the Islands was banned from 2007 until 2013, when it was argued that doing so violated World Trade Organization rules.

With tradition going hand-in-hand with commerce, poultry suppliers don’t really have a reason to try and change domestic consumer appetites for the tails. In preparing his research into the missing treat, Carolan says he had to search high and low before finally finding a source of tails at a Whole Foods that was about to discard them. "[You] can't expect the food to be accepted if people can't even find the piece!"

Unless the meat industry mounts a major campaign to shift American tastes, Thanksgiving will once again be filled with turkeys missing one of their juicier body parts.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

arrow
Animals
10 Juicy Facts About Sea Apples

They're both gorgeous and grotesque. Sea apples, a type of marine invertebrate, have dazzling purple, yellow, and blue color schemes streaking across their bodies. But some of their habits are rather R-rated. Here’s what you should know about these weird little creatures.

1. THEY’RE SEA CUCUMBERS.

The world’s oceans are home to more than 1200 species of sea cucumber. Like sand dollars and starfish, sea cucumbers are echinoderms: brainless, spineless marine animals with skin-covered shells and a complex network of internal hydraulics that enables them to get around. Sea cucumbers can thrive in a range of oceanic habitats, from Arctic depths to tropical reefs. They're a fascinating group with colorful popular names, like the “burnt hot dog sea cucumber” (Holothuria edulis) and the sea pig (Scotoplanes globosa), a scavenger that’s been described as a “living vacuum cleaner.”

2. THEY'RE NATIVE TO THE WESTERN PACIFIC OCEAN.

Sea apples have oval-shaped bodies and belong to the genus Pseudocolochirus and genus Paracacumaria. The animals are indigenous to the western Pacific, where they can be found shuffling across the ocean floor in shallow, coastal waters. Many different types are kept in captivity, but two species, Pseudocolochirus violaceus and Pseudocolochirus axiologus, have proven especially popular with aquarium hobbyists. Both species reside along the coastlines of Australia and Southeast Asia.

3. THEY EAT WITH MUCUS-COVERED TENTACLES.

Sea cucumbers, the ocean's sanitation crew, eat by swallowing plankton, algae, and sandy detritus at one end of their bodies and then expelling clean, fresh sand out their other end. Sea apples use a different technique. A ring of mucus-covered tentacles around a sea apple's mouth snares floating bits of food, popping each bit into its mouth one at a time. In the process, the tentacles are covered with a fresh coat of sticky mucus, and the whole cycle repeats.

4. THEY’RE ACTIVE AT NIGHT.

Sea apples' waving appendages can look delicious to predatory fish, so the echinoderms minimize the risk of attracting unwanted attention by doing most of their feeding at night. When those tentacles aren’t in use, they’re retracted into the body.

5. THE MOVE ON TUBULAR FEET.

The rows of yellow protuberances running along the sides of this specimen are its feet. They allow sea apples to latch onto rocks and other hard surfaces while feeding. And if one of these feet gets severed, it can grow back.

6. SOME FISH HANG OUT IN SEA APPLES' BUTTS.

Sea apples are poisonous, but a few marine freeloaders capitalize on this very quality. Some small fish have evolved to live inside the invertebrates' digestive tracts, mooching off the sea apples' meals and using their bodies for shelter. In a gross twist of evolution, fish gain entry through the back door, an orifice called the cloaca. In addition expelling waste, the cloaca absorbs fresh oxygen, meaning that sea apples/cucumbers essentially breathe through their anuses.

7. WHEN THREATENED, SEA APPLES CAN EXPAND.

Most full-grown adult sea apples are around 3 to 8 inches long, but they can make themselves look twice as big if they need to escape a threat. By pulling extra water into their bodies, some can grow to the size of a volleyball, according to Advanced Aquarist. After puffing up, they can float on the current and away from danger. Some aquarists might mistake the robust display as a sign of optimum health, but it's usually a reaction to stress.

8. THEY CAN EXPEL THEIR OWN GUTS.

Sea apples use their vibrant appearance to broadcast that they’re packing a dangerous toxin. But to really scare off predators, they puke up some of their own innards. When an attacker gets too close, sea apples can expel various organs through their orifices, and some simultaneously unleash a cloud of the poison holothurin. In an aquarium, the holothurin doesn’t disperse as widely as it would in the sea, and it's been known to wipe out entire fish tanks.

9. SEA APPLES LAY TOXIC EGGS.

These invertebrates reproduce sexually; females release eggs that are later fertilized by clouds of sperm emitted by the males. As many saltwater aquarium keepers know all too well, sea apple eggs are not suitable fish snacks—because they’re poisonous. Scientists have observed that, in Pseudocolochirus violaceus at least, the eggs develop into small, barrel-shaped larvae within two weeks of fertilization.

10. THEY'RE NOT EASILY CONFUSED WITH THIS TREE SPECIES.

Syzgium grande is a coastal tree native to Southeast Asia whose informal name is "sea apple." When fully grown, they can stand more than 140 feet tall. Once a year, it produces attractive clusters of fuzzy white flowers and round green fruits, perhaps prompting its comparison to an apple tree.

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios