Coelacanth: Habitat

Summary: Where do coelacanths live? Join Kiersten as she talks about the habitat of the coelacanth.

 

For my hearing impaired listeners, a complete transcript of this podcast follows the show notes on Podbean.

 

Show Notes: 

A Fish Caught in Time: The Search for the Coelacanth by Samantha Weinberg

“Madagascar may be a secret stronghold for ‘living fossil’ fish” by Stephanie Pappas, www.livescience.com

African Coelacanth, NOAA Fisheries, www.fisheries.noaa.gov

Coelacanth, Smithsonian, https://ocean.si.edu/ocean-life/fish/coelacanth

Music written and performed by Katherine Camp

 

Transcript

(Piano music plays)

Kiersten - This is Ten Things I Like About…a ten minute, ten episode podcast about unknown or misunderstood wildlife.

(Piano music stops)

Welcome to Ten Things I Like About… I’m Kiersten, your host, and this is a podcast about misunderstood or unknown creatures in nature. Some we’ll find right out side our doors and some are continents away but all are fascinating. 

This podcast will focus ten, ten minute episodes on different animals and their amazing characteristics. Please join me on this extraordinary journey, you won’t regret it.

This episode continues the coelacanth and their habitat is the third thing I like about this amazing animal.

We are still learning more and more about the coelacanth everyday. And one of the things we’re still learning about is their habitat. Where exactly do these behemoths live? The information I’ll give you in this episode is what we know to date, but the future could show us something different.

When the coelacanth was discovered off the coast of South Africa eighty-five years ago we had no idea where it came from, but we did know where it was caught. The fisherman caught it off the coast of South Africa in the Indian Ocean at a depth of forty fathoms, or 240 feet. We didn’t see another one until 1952. This one was caught near the Comoros Islands which is off the southeastern coast of Africa in the Indian Ocean. Now we had an idea of where we might find more.

It wasn’t until later that researchers went to the islands and talked to the native islanders asking about this giant fish. (Quick note here, we should do more of this. Native inhabitants of areas that others explore know a lot about local wildlife. Why reinvent the wheel when you have so much information right in front of you, if you are just willing to listen?) Now, back to the coelacanth. Locals of the Comoros Islands were familiar with the coelacanth and had even eaten them in the past. Focusing on this area, several more coelacanth were found.

In 1998, more coelacanth were discovered in Indonesia, half a world away. The question was how did they get there? Did they migrate? Do they do that seasonally? Did a few get lost? Did they get washed away in a storm? Or have they been there this whole time?  Turns out, they’d been there the whole time.

When the Indonesian coelacanth was discovered, scientists performed DNA tests to see if they were related to the African coelacanth or possibly a new species. Once again these ancient fish surprised us, the two populations were indeed two separate species. According to research available at the recording of this episode it looks like these two species may have evolved separately.

The African coelacanth’s scientific name is Latimeria chalumnae and the Indonesian coelacanth’s scientific name is Latimeria menadoensis. I mention this because they were named after Marjorie Courtenay-Latimer the discoverer of the first specimen in 1938 and I think it’s wonderful that this woman of science gets props for her discovery. 

Before we get into where exactly these fish are found around the global let’s talk about at what depths they are found. This first specimen found in 1938 was caught by fisherman at a depth of 40 fathoms or 240 feet. For quite some time we thought this deepwater depth is where they lived.  But we now know that they actually inhabit, mesopelagic waters, also known as the “twilight zone”, that reach depths of 650 feet to 1,300 feet. That’s a lot deeper that we thought or ever expected. We’re not sure why the original specimens were caught in the shallower depths, but they could have been hunting or they could have been ill and unable to control their swim bladders properly and floated up into shallower depths. More recent sitings of both species have been between 300-500 feet deep, so obviously these fish are doing something important at these depths. Now that we know at what depths the coelacanth can be found let’s look at where in the world we can find them.

Let’s investigate the habitat of the African coelacanth, Latimeria chalumnae, first. These coelacanth are found in the Indian Ocean near the coasts of southeastern Africa, Madagascar, and the Comoros. The first one found in 1938 was caught off the coast of South Africa but after that no more were seen in the area. More specimens were found near the Comoros islands, that are situated between Madagascar and the east coast of Africa, in the 1950s so it was thought that the first one found in 1938 was a stray individual from the Comoros area. But when diving technology advanced, divers using “rebreathers” which allow to you dive deeper underwater than typical scuba gear, and later on researchers using submersibles, saw resident individuals in South African waters. Specimens have been caught off the coast of Madagascar  and off the coast of Mozambique and Kenya.

Latimeria menadoensis, also known as the Sulawesi coelacanth is from Indonesia. Two specimens were caught off the island of Manado Tua at the northeastern tip of Sulawesi. Later two more were sighted 225 miles southwest of this island. 

In both regions, coelacanth inhabit temperate waters near steep rocky slopes of volcanic islands. In the daytime, the Comoran coelacanths can be found clustered together in caves in submarine lava deposits. In the evenings they venture out to hunt. The two individuals observed from a submersible in Indonesia were seen in a deep carbonate cave at a depth of 500 feet. Both species seem to depend on caves, canyons, and cliff ledges for almost all aspects of their life. Sleeping during the day and hunting at night seem to be done in and around these structures. 

in 2021 researchers found evidence that Madagascar might be an unknown haven for coelacanths. In a new review of Madagascar fishery bycatch, 34 specimens were confirmed to be coelacanths. These catches have never been reported to scientists or conservationists before now. This indicates that coelacanth may be living off the coast of Madagascar. 

When we look at the history of this large island off the coast of Africa, it could be completely possible. Coelacanth are actually older than the island of Madagascar by about 330 million years, but Madagascar has had a coast line for around 88 million years; whereas, the Comoros Islands is only 15 million years old. Based on this history and recent bycatch reports, researchers think that Madagascar might be their ancestral home. More research will need to be done to find out if this is true, but it just one more thing that adds to the mystery of the coelacanth.

I am so glad you went deep sea diving with me today to learn about the habitat and species of the coelacanth because it’s my third favorite things about them.

If you're enjoying this podcast please recommend me to friends and family and take a moment to give me a rating on whatever platform your listening. It will help me reach more listeners and give the animals I talk about an even better chance at change. 

 

Join me next week for another episode about the coelacanth.  

 

(Piano Music plays) 

This has been an episode of Ten Things I like About with Kiersten and Company. Original music written and performed by Katherine Camp, piano extraordinaire.