The coelacanth, a type of fish that has survived for more than 360 million years, is facing a huge threat of an oil spill. Oil exploration is set to begin near the habitat of the critically endangered fish and it could very likely wipe out the entire remaining population.
This is such a big deal because the fish have managed to outlive dinosaurs, but now their existence is being threatened. The following article covers all you need to know about the species of fish that was rediscovered in the 1930s, millions of years after they were thought to have gone extinct.
What are Coelacanths?
Coelacanths are ancient fish that lurk between 100 and 200 meters below the ocean’s surface. Older than dinosaurs, they weigh as much as an average-sized man, are the most endangered fish in South Africa, and are among some of the rarest fish in the world.
The 1.5 meter-long creatures live near the Comoros Islands, but they’ve also been spotted off the eastern and south-eastern coasts of Africa. The fish spend their time in cavities inside submarine volcanic rocks and they only venture out at night to feed. Their diet consists of mostly octopus, squid, and cuttlefish.
The coelacanth, which is related to lungfishes and tetrapods, were thought to have become extinct in the Late Cretaceous period, around 66 million years ago. They follow the oldest-known living lineage of Sarcopterygii, which means they are more closely related to lungfish, reptiles, and mammals than to the common ray-finned fishes
Rediscovering the Coelacanth
But to the surprise of many, on December 23, 1938, a coelacanth was found off the coast of South Africa, off the Chalumna River (now Tyolomnqa). Its discovery after it was believed to have gone extinct makes the coelacanth the best-known example of a Lazarus taxon, an evolutionary line that seems to have disappeared from the fossil record, only to reappear much later.
Coelacanths in Sodwana Bay
The discovery in 1938 was followed by the capture of several more coelacanths off the Comoros Islands in the early 1950s, confirming the coelacanths were definitely not extinct. Then, in December 2000, divers found a small coelacanth colony in underwater canyons near South Africa’s Sodwana Bay, adjacent to the iSimangaliso Wetland Park and World Heritage site.
Coelacanth Encounter in December 2000
While exploring the depths of Sodwana Bay, scuba diver Pieter Venter came face-to-face with something no diver had ever seen before. At 320 feet below the water’s surface, he and his colleagues encountered a coelacanth. The team then recorded three fish in the area and on that dive and in a later expedition, confirmed that a colony of these so-called “living fossils” lurked in deep water canyons in the bay.
Considered a Living Fossil
For a long time, the coelacanth was considering a “living fossil” because scientists thought it was the sole remaining member of a taxon otherwise known only from fossils, with no close relatives alive. It was believed that it evolved into its current form approximately 360 million years ago, however, recent studies have shown that coelacanth body shapes are more diverse than previously thought.
Learning About Our Oceans
Since the discovery in 1938, the creature has been a sensation and living proof that life is more resilient than we had imagined. It’s also served as a reminder of how little we actually know and understand about our oceans. Being that we are still learning about the fish, it’s been difficult for scientists to determine how many of them are left in the oceans.
Being that there are only two known species of coelacanths: one that lives near the Comoros Islands off the east coast of Africa, and one found in the waters of Sulawesi, Indonesia, it’s believed that there are not many fish left in the sea. Coelacanths can be huge, weighing more than 198 lbs and scientists estimate that they can live up to 60 years or more.
Unique Characteristics of Coelacanths
The most striking feature about the coelacanth is that it has paired lobe fins that extend away from its body like legs and move in an alternating pattern, like a trotting horse. Other characteristics include a hinged joint in the skull which allows the fish to widen its mouth for large prey, an oil-filled tube which serves as a backbone, thick scales common only to extinct fish and an electrosensory rostral organ in its snout, according to National Geographic. But the most interesting trait about coelacanths is how it reproduces.
“We know hardly anything about their reproduction,” says Kathrin Lampert of Ruhr University Bochum in Germany. The only thing known about coelacanths is that their gestation period is an impressive three years and they bear live young. In 2013, Lampert DNA fingerprinted two dead pregnant female coelacanths and their offspring. The fish were accidentally caught by fishing boats, one off the coast of Mozambique in 1991 and the other near Zanzibar in 2009.
Not so Many Fish in the Sea?
“For both, it was very clear there was only one man involved,” Lampert told News Scientist. She and her colleagues were stunned by the discovery as they expected the females would mate with multiple partners to maximize the genetic diversity of their offspring. However, she says that previous research has shown that they live in groups in caves, providing many opportunities for females to play the field. “So it’s unlikely they are restricted by mate choice,” Lampert says.
But a bigger question remains of how they actually mate. In order to inseminate a female, a male would need to penetrate her cloaca and inject its sperm. However, male coelacanths appear to lack the necessary equipment for this. “They have nothing penetrative, no apparent adaptations for inseminating females,” Lampert explains.
Mating is Extremely Rare
She believes that it’s possible that they have unusual genitalia that grow periodically, do the job, and then disappear. More likely, she says that to mate there has to be a very special spatial alignment between the male and female parts, and this is so seldom achieved that mating is extremely rare. While it’s obvious why coelacanths mate so infrequently, they do tend to bear many children when they do.
The offspring found in two coelacanths were 23 and 26, respectively. The offspring seemed very large at birth, about a third of the length of adults. This explains why the female undergoes such a long gestation period because growing the young to a large size boosts the chances of escaping a hungry neighbor. However, no matter how big the coelacanths are, all of them are susceptible to the danger of oil spills.
Oil Spill in Exploration Area Block ER236
Dr. Andrew Venter, the chief executive of Wildtrust, told The Guardian that an oil spill could be a disaster. “The Deepwater Horizon oil spill in the Gulf of Mexico in 2010 decimated fish populations–so if we had an oil spill off iSimangaliso it is very likely it could wipe out these coelacanths,” Venter said. In August 2018, the Italian energy group Eni announced plans to drill in an exploration area known as Block ER236, a 250-mile long area just 25 miles south of Sodwana Bay.
The Sodwana coelacanths are about 25 miles from the northern boundary of the Eni exploration area, which makes the threat a real one. Coelacanth expert, Mike Bruton, also told The Guardian that the fish are specialist creatures, sensitive to environmental disturbance. “Anything that interferes with their ability to absorb oxygen, such as oil pollution, would threaten their survival. The risk of oil spills or blowouts during exploration or future commercial production in Block ER236 is a source of serious concern.”
In 2017, Eni commissioned a mandatory environmental impact assessment (EIA) but the scoping report makes no mention of the potential threat to the Sodwana coelacanths. Instead, the report suggested that coelacanths were unlikely to be found next to the exploration wells. In response to the fears that the fish could be wiped by leaks or undersea blowouts, the oil drilling company issued a statement saying: “Eni always applies the highest operational and environmental standards, which often exceed local compliance regulations.”
“No Specific Threat”
“Prior to any operation we undertake sensitivity mapping to identify sensitive offshore marine habitat which guide our planning,” they said. “Specialist studies have been conducted for both marine ecology and oil spill modeling scenarios and no specific threat has emerged in relation to this.” But Bruton said studies on coelacanths caught off the coasts of Indonesia and Tanzania showed the remoteness of their habitat had not protected them from exposure to pollutants such as PCB and DDT.
Keeping Coelacanths Around Is Important
If oil were spilled in the ocean, Bruton feared the coelacanth colony could be destroyed. “The risk needs to be carefully evaluated before this commercial venture has progressed too far and it is too late,” he said. “Oil spills do not respect the boundaries of marine protected areas.” The threat isn’t only to coelacanths, but instead, to all fish along the coast of Africa and in the Comoros.