by Kentaro Ohno さん https://www.flickr.com/photos/inucara/ - https://www.flickr.com/photos/inucara/8442067878/, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=26348779

Coelacanths: Living Fossils From 65 million years ago

Do coelacanths hold a priceless secret to longevity?

Given it’s been swimming our oceans for around 360 million years, it’s a fair bet that it’s mastered the cream of core survival skills.

Perhaps its ability to keep a low profile is part of its strategy…

Science believed it was extinct until a living specimen was caught in 1938…

You see, once you’ve earned the prestigious title of extinct, it kinda stays with you—like…forever…

Your secrets die with you also, leaving the detectives with little more than fossils and painstaking speculation.

A Joyous Comeback For Science!

This apparent extinction fake-out was a cause for scientific celebration

Why we hear you ask?

Well, it’s because these creatures are strongly linked to life’s progression from the oceans to the land.

The discovery of a living coelacanth represented significant potential for evolutionary revelations. Science heaven!

Let’s go swimming with a very rare yet not-so-missing link. The coelacanth…

A Big Fish with a Big Mouth and a Little Brain

In anybody’s language, the coelacanth latimeria is a big fish…

When fully grown it can be more than 6 feet long, and weigh in at more than 200 pounds….

To put that in perspective, that’s longer and heavier than the average American human male!

DID YOU KNOW?

Coelacanths have a proportionately big mouth too. However, it has a unique feature called an intracranial joint. 

Essentially, an intracranial joint is a hinged mouth. Its head can pivot upwards, allowing its mouth to open extra wide, presumably for eating larger prey.

Coelacanth Brain

the coelacanth brain is minuscule…

Conversely, the coelacanth brain is minuscule. Most of their brain cavity is full of fat, only 1.5 percent of this space is brain. It seems a big brain has little to do with longevity.

A 12-foot saltwater crocodile has a brain the size of a walnut, yet has been around for over 240M years.

Given these facts alone, it would appear longevity is all about having a big mouth and a small brain.

Hmmm… definitely something to think about right?

By A3 Baard - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=80591778
Preserved Coelacanth from SAIAB exhibition in Makhanda Grahamstown (2)

Coelacanth Weird Bits

Most of the fish we are familiar with are actinopterygians. This means “ray-finned”. Salmon, mackerel and trout, for example, are “ray-finned”. Their fins are supported by spines.

Coelacanths are sarcopterygians or “lobe-finned” fish. There are no spines or solid bones in their fins.

Their fins are a fleshy protrusion. It is this feature that holds the evolutionary links, which we’ll discuss later…

Links to Evolution

Interestingly, the four fleshy fins move in an alternating pattern more like a four-legged land animal, such as a horse or dog.

Therein lies another hint to the sea-to-land evolutionary link.

If you want to know more about interesting Coelacanth features…

Watch the cool video below…

A Scientist Demonstrating Features of a Preserved Coelacanth

While these creatures are vertebrates, their spine is actually hollow and filled with fluid. Called a notochord, the spine is much the same as the early vertebrates of millions of years from the past.

FUN FACT

Coelacanth is Greek for hollow spine, this is where it got its tricky name.

Electro-Sensory Perception?

Many fish species use an electric sensory receptor on their snouts to find prey and navigate.

This includes but is not limited to sharks, dolphins, countless fish species, and weirdos such as the Australian platypus.

The coelacanths too, use electroreception to find its dinner. However, where other fish have thousands upon thousands of sensory canals, they have only three paired sensory canals.

Other species send electronic messages to different parts of their bodies, such as the head. They send messages directly to the dorsal snout – their top lip, more or less.

Purpose

Researching scientists believe this is the first discovery of a low-resolution electro-detector designed specifically for catching prey.

It is also speculated that coelacanths use this snout mounted sensory organ to avoid running into doors and falling down the stairs. Simple navigation stuff.

Nothing to Look at Here…Or is there?

Relative to some of the fish that live in its neighborhood, coelacanths aren’t really that weird-looking. A little prehistoric, yes. But pretty ‘normal’ nonetheless.

These creatures have a grey/brown color with interesting pale blotches. Its scales are very thick, looking like medieval armor, but that’s not so strange…

It uses normal-looking fish gills to breathe, and most of its body parts look proportionate.

By Ghedoghedo - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=63980943
Coelacantheformes Fossil From the Natural History Museum of Bamberg (3)

Not so common

Its eyes appear to be symmetrically placed on its head, not too big, or small, and it would appear to swim gracefully if a little lethargically.

Compared to the sunfish, or the blobfish and the angler fish, it’s really only its limb-like fins that stand out as odd.

In fact, it’s really a very attractive sea creature…

However, when we open these creatures, that is, dissect it, we find a superfluous lung inside its belly?

The Evolution Plot Thickens

It was the Sarcopterygians or lobe-finned critters, that took life out of the water to breathe air on land.

They’re known as tetrapods, Greek for 4 feet. 

About 400M years in the past

It was one of these tetrapods, that gave rise to all vertebrates, including the dinosaurs and, yes, human beings. Somewhat later of course.

It is understood that these creatures are ancestors of the tetrapods, which probably explains the lung and the lobed fins.

New Discovery

However…

More recent studies suggest that it is the lungfish, a close relative of coelacanths that is more closely related to the first land-dwelling tetrapods. 

Lungfish, coelacanths and tetrapods are assumed to have diverged, or branched off on a separate evolutionary path about 390 million years in the past.

Science speculates with some authority…

That coelacanths are closely related to the tetrapod. It simply took a different path.

Diver Taking Photographs Underwater
Diver Taking Photographs Underwater

Distribution and Lifestyle of the Ancient Coelacanths 

The coelacanth latimeria chalumnae is particularly rare…

The first coelacanth latimeria chalumnae was discovered in the Indian Ocean on the coast of South Africa in 1938.

60 years later, another type of its species called Latimeria menadoensis was discovered in Indonesia.

Analysis showed that the coelacanth latimeria chalumnae and latimeria menadoensis are closely related and likely share a common ancestor.

However, there are significant differences between the species.

Where do They Live?

By Anaxibia - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=7709497
Geographical Distribution of Coelacanths (4)

These creatures are mostly found off the east coast of the African continent

Locations include the waters off Kenya, Tanzania, Mozambique, South Africa, Madagascar, Indonesia, Comoros (off the east coast of africa) and the indian ocean.

The Latimeria, or Indonesian species is found off the coast of Manado Tua Island, Sulawesi, Indonesia in the Celebes Sea.

Coelacanths can be found in water as deep as 2300 feet…

Coelacanths can be found in water as deep as 2300 feet, that’s nearly half a mile!

However…

The regular haunt is more like 300 to 600 feet mark, feeding and living in the benthic zone. That is the ocean floor. 

This is still very deep water, and relatively cold. It appears cold water is more suitable for its breathing, and their sensitive eyes are more suited for the dark…

In fact, they are rarely seen during full moons.

DID YOU KNOW?

Coelacanths were thought to have become extinct,but were rediscovered in 1938 off the coast of South Africa

Relatively Little is Known About Love and Breeding of Coelacanths

It is understood that coelacanths can live up to 60 years. However, it is believed they do not reach sexual maturity until age 20. 

This would support the notion that they were never a prolific species at any time in their considerably lengthy history.

By A3 Baard - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=80591779
Preserved Juvenile Coelacanth SAIAB exhibition in Makhanda Grahamstown (5)

Coelacanth Gestational Period

Once mature, the male will fertilize the eggs, which are retained inside the female. After a 13 month gestation period,fully formed live young are released into the water.

Mom can expect from 5 to 25 pups each time. The pups are completely independent and able to survive on their own from the moment they are born.

NOTE

To give you an idea of size, one pregnant mom was found to have 26 young pups inside her with each measuring over 12 inches long. 

If these creatures touch one another, they kind of retreat as if respecting the others personal space, or retreating to its own.

DID YOU KNOW?

Interestingly, Coelacanths are known to retreat when approached by large things such as research submersibles.

Scientists surmise that this flight behavior suggests caution. It may indeed be the prey of predators such as sharks.

A Casual Feed 

Coelacanths head out to feed in the evenings. It’s not a predatory feeder, it’s more of an opportunist, drifting with the current and eating anything that comes into its path, swallowing it whole.

It swims lethargically as if it’s in no hurry at all. However, it is known to cover as much as 5 miles a night while feeding.

Menu items include other fish and cephalopods. Cephalopods include creatures such as octopus, squid, and nautilus, for example.

Metabolism of the Coelacanth

They have a very sluggish metabolism. This certainly has benefits in an ocean zone like the twilight zone, as finding food can be pretty tough. 

It’s believed that its slow metabolism and ability to do without food for longer periods, may have saved it from extinction.

How so?

Food was tough to come by when most of the life on earth went extinct 66 million years ago.

Coelacanths as Prey

Every yin has a yang. While they may have survived Armageddon, it is slow and lazy – every day’s a holiday – disposition, may have its drawbacks.

Scientists and divers have observed shark bites on them. One would have to assume that some got it a lot worse than just a few scars.

Fishing Nets

Major Threats

Like so much of the marine life in our oceans, the coelacanth’s greatest threat is from commercial fishing by-catch. 

The oil fish trade was particularly destructive

Because oil fish inhabit the same waters as the coelacanth, and feed at night, as coelacanths do. many were caught unintentionally. 

Sold for Research

Before the ’80s these creatures were simply thrown back.

However, following the growth of scientific interest…

Fishermen began trading them with scientists.

To encourage fishermen to avoid catching them…

Incentives were offered to local fishermen in the form of more seaworthy boats.

This allowed them to fish beyond the habitat of coelacanths.

Unfortunately, over time the motors for the new boats fell into disrepair…

The fisherman simply returned to the original fishing grounds, putting further pressure on the population of coelacanths.

New Conservation Methods

In 2014, a method of deep water release was devised for returning unintentionally caught coelacanths…

A hook and weight were connected to the fish that would release from the fish when it hit the ocean floor of the coelacanth’s habitat.

Unfortunately, the jury is still out as to whether the intervention was successful or otherwise. Data is not readily available.

Various countries have funded or provided habitat protection

This includes broader habitat protections for many species, including that of the coelacanth.

Check out this cool video of divers finding a Coelacanth…

Divers Finding a Coelacanth

Unregulated fish tourism doesn’t seem to be an issue for these creatures…

The stresses of tourism has had significant impacts on species such as the whale shark, and other easily accessed tropical reefs, and its inhabitants.

FUN FACT

Coelacanths are not harmful in any way to humans. In fact, they are considered a very gentle and peaceful creatures.

The Coelacanth for Human Consumption

…coelacanths can consider themselves very lucky that it evolved with a horrible flavor.

Given the way we humans ravage the ocean’s resources, coelacanths can consider themselves very lucky that it evolved with a horrible flavor.

It’s completely unsuitable for human consumption.

Its flesh contains a delicious cocktail of oil, urea and wax esters…

Its flesh contains a delicious cocktail of oil, urea and wax esters. While you might be able to polish your car with these creatures, eating them is out of the question.

If those wonderful ingredients weren’t enough, there’s a host of other nefarious compounds that will make diners sick. 

Its scales ooze mucus, the flesh is slimy, and it smells disgusting.

Hungry yet? Wanna coelacanth BBQ?

Unfortunately, Coelacanths are Endangered

The International Union for Conservation of Nature (IUCN) has classified Latimeria chalumnae, the African (West Indian Ocean) Coelacanth, as critically endangered.

It is estimated that there are only 500 left in the wild.

Latimeria menadoensis, the Indonesian species, is listed by the same official body as vulnerable…

It is estimated that there is a much healthier population of around ten thousand individuals.

Nonetheless, considering the size of the ocean and the expanse of their habitat, ten thousand still seems like a precarious number.

Few in Numbers

Scientists suggest, that even in their heyday millions of years in the past, their species were not such prolific creatures.

It would seem a horrible twist of fate, that their species could survive over 300M years, including a major, almost complete extinction event, only to succumb to human carelessness.

Is a small brain, a low social profile, a big mouth, and a profoundly lazy disposition the meaning of life?

These creatures pose a pretty strong argument in the affirmative.

Or, is it a twist of fate and a bunch of dumb luck, that sees them cruising leisurely about the contemporary benthic zone?

These species have a pretty significant heritage and bloodline

In fact, when you think about it, if evolution twisted a little differently, it may be their species paying taxes, driving cars and losing itself in its mobile phone.

A Different Path

At some point around 400M years in the past, coelacanths diverged from their ancestors. They managed to stay in the ocean, and its ancestors became us.

It truly mind-blowing when you think about it.

Having survived all of this time and unimaginable chaos, it seems ridiculous that now its future hangs precariously in the balance.

Surviving global extinction events obviously requires some serious survival skills.

However, there are few, if any species that possess the capacity to survive humankind.

Can you see the irony here?

Having endured for millions of years, changing very little, if at all…

The fate of these creatures lies in the hands of the evolved ancestor it diverged from over 400M years ago.

Now that you’ve discovered how this supposedly extinct creature came back to life.

If you think that people you know might be intrigued by the Coelacanth’s rise from the dead

Feel free to share this content to let your friends discover this living fossil too!

  1. (Featured Image) Preserved Coelacanth from Numazu Deep blue-Aquarium Shizuoka Japan – by Kentaro Ohno さん – https://www.flickr.com/photos/inucara/ – https://www.flickr.com/photos/inucara/8442067878/, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=26348779
  2. Preserved Coelacanth from SAIAB exhibition in Makhanda Grahamstown – By A3 Baard – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=80591778
  3. Coelacantheformes Fossil From Natural History Museum of Bamberg – By Ghedoghedo – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=63980943
  4. Geographical Distribution of Coelacanth (4) – By Anaxibia – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=7709497
  5. Preserved Juvenile Coelacanth SAIAB exhibition in Makhanda Grahamstow – By A3 Baard – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=80591779

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