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 LE
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 