There is a population of dwarf crocodiles (Osteolaemus tetraspis) in Gabon that live their entire lives inside a cave, and has orange skin because of acidic bat guano
The dwarf crocodile (Osteolaemus tetraspis) is an African crocodile that is the smallest crocodile alive. It is found on the western coast of Africa, and live in different freshwater sources such as small rivers, swamps, and mangroves. They rarely bask in the sun, which is pretty different from most crocodile species.
They are also “only” about 1.5 meters long, with a weight of between 18 and 32 kilos (but some can be a lot heavier), but are not really dangerous for humans. In fact, they tend to eat insects, frogs and freshwater crustaceans such as shrimps and crabs, and not really prey on things that are much bigger than these things. Sure, it would probably hurt to be bitten, but you would survive it without any trouble.
A dwarf crocodile. Image by Wikimedia Commons users Thesupermat, posted with the GNU Free Documentation License.
While the dwarf crocodile in itself might not be very special, they do have a very unique population that lives in caves in certain parts of Gabon, and that is what we are going to be learning more about today!
The cave-dwelling dwarf crocodiles of Gabon
We find the Abanda caves deep in the rainforest jungle of Gabon in Africa. This huge cave houses 50,000 bats, millions of insects from many different species, and surprisingly a population of dwarf crocodiles.
These cave-dwelling dwarf crocodiles live in complete darkness all year long, and have probably never seen any real light in their entire life span. Since they have no need for seeing things because of the darkness, these crocodiles have turned blind, and rather uses their other senses to find food in the caves.
Not only have their eyes adapted to living in cave conditions, they also have a completely different diet from the members of the same species that live outside the cave. Instead of crustaceans and insects, they feed on bats, crickets and most interestingly large amounts of algae.
A cave-dwelling and a normal dwarf crocodile next to each other. Image by Olivier Testa, posted with the GNU Free Documentation License.
From what you can see in the picture, the biggest change from the other member of the species is that they are orange, not dark grey / brownish. While the exact cause for this strange color difference is still not fully known, scientists believe that the orange color comes from the acidic urea in the bat guano (yes, that is bat poop), which chemically alter their skin to over time change color into orange.
The first scientific expedition into the cave yielded sightings of nine different crocodiles, where two of them were located after a 7-meter deep pit. This leads the scientists to believe that these two crocodiles are unable to get up and out from the cave, and are living their entire life inside the cave. The rest of the crocodiles are theoretically able to leave the cave, but no one knows if they actually do this, or if they simply spend their entire life down there.
Anyway, a few years later another expedition took place, and this time they were able to find 20 different orange cave-dwelling crocodiles. There might be more of them down there, but it seems likely that the population is very small. How such a small population has survived for such a long time is beyond my knowledge, but apparently they have been able to find a way to do this.
Are the genetically different to the crocodiles outside?
A genetic test of the cave dwarf crocodiles revealed that they have a few percentage difference in genes from the dwarf crocodiles found outside the cave, and were tested against different dwarf crocodiles populations from several parts of Gabon in order to prevent a skewed result based on random sampling. A few percentage difference in genetics might not sound like a whole lot, but it is in fact enough to tell the scientists that they have been living isolated from the other crocodile populations for several thousand years. This rules out the potential theory that they are going outside to breed with the non-cave crocodiles, and reinforces the theory that they are mostly isolated in the caves.
Thanks for reading
Thank you very much for taking the time to check out my post about the cave-dwelling dwarf crocodiles. I hope you enjoyed it, and just follow the links in the text to find more information.
Being A SteemStem Member
Thank you for the upvote!
I'm really surprised to hear about a crocodile eating insects. I'm not surprised about the crustaceans or frogs, but I never would have considered something like crickets being a reliable food source. I mean, I get that animal's primary food sources are insects, but unlike an ant-eater, the anatomy of the jaw structure isn't really suitable. Can you really image what that would look like? chomping away at crickets as they zip by. I wonder how many would be a sufficient lunch...
Yeah, it is pretty strange! It would be interesting to see how their diet is by percentages. So far I have only found sources that say that they eat crickets, algae and bats, but I would be very interested to learn what their main food is, and how many crickets they typically eat.
One thing that is pretty cool is that crocodiles don't really need to eat much if they don't move. Some species can easily go a year or longer without any food, but again, I'm not sure how this is like for the cave-dwelling dwarf crocodiles.
Yeah, and it's crazy to think of how long some lifeforms remain motionless until food arrives. I've heard that crocodiles, alligators, some snakes, and most spiders use this strategy . It's kind of weird to think about doing nothing for such long time frames just to eat. I'm not sure exactly how long, but I do recall seeing something about how ticks will remain possibly motionless for years until a host walked by, to which it then attaches and gorges it'self with blood until the next wait. It's an interesting way to life.
I agree that this is really cool! Now I kind of want to try to find out which animal species is capable of sitting completely still the longest :)
Interesting article @valth so are they actually classifying it as a sub-species of the main dwarf crocodile family given is mild genetic variation and living conditions, or are the keeping it in the same genus as the other non cave dwelling relatives?
Thanks for a great question, @robmenzies!
As of right now they are just considered a population of the dwarf crocodiles. However, their DNA is absolutely different enough to classify them as their own subspecies, and some scientists even argue that they should be a species of their own. The reason why they are not classified as their own subspecies is because of lack of published knowledge about them, so I expect this to change at one point in the future. I hope this made things clear, but let me know if you want more details ;)
Best regards from @valth
Thanks @valth for the clarification.
given that they look completely different from the picture you posted and completely different habitats i would tend to think that they should be their own species.
If my mind serves me well i remember watching on National Geographic several years ago on one of those island of snakes that had the island divided in two by a range of mountains that there two distinct species of snakes on the island, despite no new snakes being able to come to the island. I suspect Darwinistic evolution at its best.
Yeah, I would prefer them to be two separate species as well, but there are a few things that needs to be clarified first. For starters, if any of the crocodiles within the cave ever comes outside and breed with the non-cave crocodiles, then it no longer makes any sense to refer to them as their own species.
That's a good example of specification where one species evolved into two distinct species. This is a common way for species to develop, but it can be pretty difficult to determine and agree upon at which point we should consider them a new species.
Seems like a good job for the block chain tag and release them all with RFID and see if any venture for the cave.
Hehe, yeah, that would be interesting!
Very interesting post! Quality content, i upvoted it!
Also this may just be a difference in two individuals but i noticed the cave dwarf crocodile has larger eyes. Interesting, considering it's blind.
And on an unrelated note, i think you should bring back Mushroom-Monday!
That's an interesting observation. I didn't read anything about it in the research paper, so it might not be something that has been seen on the other crocodiles.
I might bring it back at a later point, but for now it's 50cm snow outside, and no mushroom in sight, so I'm rather saving it for summer and fall :)
Thanks for stopping by and leaving a comment!
Så kult! Har valgt biologi på videregående nå, og synes det er veldig interessant. fuglt! :)
Biologi er uten tvil et av de beste fagene på videregående, selv om det kan virke litt overveldende for de som ikke helt interesserer seg for det. For det er mye å lære i løpet av nokså kort tid, men det er så enormt mye interessant å lære om hvordan alt liv er bygget opp og henger sammen ;) Takk for at du følger! Det er alltid fint med flere nordmenn i kommentarfeltet!
Thanks for the Info @valth
I've heard a lot about Dwarf Crocs being extremely aggressive. There was one at the Newport Aquarium in Kentucky and he seemed pretty mellow, but that was just one individual. If I had the room, I'd love to build a big enclosure for one, but I currently can't do that. Maybe one day.
You're welcome, @usmanzeb.
Oh, really? I didn't know about them being aggressive, but it makes sense. Hehe, pretty cool that you want to own a dwarf crocodile!
@valth Very Interesting article.After reading all this,i was so intrigued that i watched whole episode of BBC Earth Unplugged-dwarf crocodile.Thank you for sharing such a master piece.Thumbs up and upvote.
I'm glad you liked it! It's great to see that my post has inspired you to learn more about the dwarf crocodiles ;) Thanks for stopping by and commenting!
It's obvious that cave dwarf crocodiles have few different genes thats why they adopt different living style. Amazing thing about cave dwarf crocodile is that with such a big body they rely only on bats, insects and frogs. Orange color dwarf means crocodile who consume a lot of bat. Nice info about dwarf crocodile
Yeah, it's really amazing that this big animal is able to live off the small food sources it has in the caves. Just imagine how many bats and insects it would need to be full!
Yes, may be this is the law of nature. So we have good control over growth of insects in this way. As you told in previous post the aardwolf eat million of termite at one time. Think what happens if these monsters don't consume so much species at a time.
Yeah, that's true. Insects can multiply at an insane rate if conditions are right for them, and a few individuals can become million of them in only a few months.
The head partially looks like a dragon head. it does look like a fire breathing dragon if you look closely i mean I didn't even know something like this Exists it's a great piece of information and a nice reference for my next art work so it has helped me in both ways thank you so much for sharing this :)
You're welcome! Yeah, I guess it might look like the head of a dragon ;)
Hahaha or probably the dragon head look like a crocodile head well never know unless we know who came first :p
I'm pretty sure crocodiles came first since dragons are fictional :P
Hahahaha you bet but sometimes you can relate fiction to reality in some or the other way :p
Closest relatives of crocodiles are birds and dinosaurs. Crocodiles live on the Earth 240 million years.
Sure, I guess that's right, @barbie.doll.