The Mysterious Chambered Nautilus

While not actually a “living fossil” it is a creature that has been around since the dinosaurs with subtle changes in it’s DNA along the way. In...
By melypr1985, Jan 26, 2017 | |
  1. The Mysterious Chambered Nautilus


    I recently had the opportunity to see one of these amazing, interesting creatures in person. While I don’t condone keeping this creature in captivity, it does happen and so we ordered one at the store. I was impressed with how well it shipped and acclimated. We had it eating only the second day and got to watch it motor around the tank for several weeks. We found the idea of having a “living fossil” in our care both intimidating and cool all at the same time.

    Photo: Seasky.org
    Nautilus Shell.jpg
    While not actually a “living fossil” it is a creature that has been around since the dinosaurs with subtle changes in it’s DNA along the way. In person, this cephalopod certainly looks like something out of prehistoric times. In my mind, I always saw them as a cross between a cuttlefish and a snail. It has a large, spiraling shell that contains the animal’s internal organs, which are kept in the larger of the chambers until a new chamber is built and the organs can be moved to the new chamber. This is constantly happening as the creature grows. The rest of the shell is made up of the empty chambers that were left when the organs were moved into the new larger space. These hold a special fluid that the nautilus uses to control it’s buoyancy in the water. It can change the density in the fluid as needed to rise in the water or dive deeper when needed. Though, the nautilus typically found around 1000 feet, they can go up to 2000 feet before being crushed by the water pressure.

    Photo by: Animal Graphics via Seagrest farms
    Chambered Nautilus B.jpg
    Like most snails (hence why I think of them as part snail and part cuttlefish), there is a “trapdoor” that lays over the opening to the nautilus’s shell. Under this door you’ll find the nautilus itself which includes about 90 tentacles, two rudimentary eyes (similar to a pin hole camera) and it’s internal organs. The tentacles are used to grab food and bring it to the “crop” where it can store food for long periods.

    I did some research on these guys when I heard we would be getting one at the store. I found that being a deep-water species they preferred water a bit cooler than we typically keep our reef tanks, though they are known to travel to the shallows at night to feed and to lay it’s eggs. They’ll eat just about anything they can find including dead fish, detritus, smaller crustaceans and even small, live fish if it’s easy enough to catch. I was able to get our nautilus to eat silver sides and krill reliably.

    In the wild the nautilus uses a tube made of tissue to propel itself around with a jet of water. It did the same thing in our tank at the store, but not much. The higher flow in the tank was a bit much and tended to push it around, so ours stayed in the calmer waters near the overflows most of the time. It also never sank below the surface of the water. I don’t know if that has something to do with the water temp, or the fact that the tank was pretty shallow (not that it would know since it never once tried). We named it “bob” since that’s all it really did in the water.

    It’s thought that the nautilus can live upwards of 20 years in the wild, but I’ve never heard of one lasting longer than a year in captivity. In our case, he was in an open-top tank and was constantly being touched, poked or picked up by our service employees. Customers were quite a bit better behaved than our employees sadly. After only a few weeks with us, the nautilus stopped eating and retreated into its shell. The “trap door” started to slide down revealing a black band under it which spelled bad news in my mind. After two days of wondering if it was alive and scared to handle it too much, we took it out and found that it was indeed dead as the “door” fell off without much prompting.

    Photo by: melypr1985
    chambered nautilus.jpg
    My experience and story ended sadly, but I hoped to use it to educate people about this awesome creature and to convince hobbyists everywhere that these animals are among those that should be left in the ocean. There are worries about the nautilus being over-fished for it’s beautiful shell and talk about it being put on the endangered species list. Until then, we should try to control our impulsive natures (difficult I know!) and leave this animal in the ocean where it belongs. It must be said that there are people out there that have cared for a nautilus, but those people are considered “expert” level aquarists. The care of this animal shouldn’t be taken on by the average Joe hobbyist.



    Reference:
    https://en.wikipedia.org/wiki/Chambered_nautilus
    http://www.seasky.org/deep-sea/chambered-nautilus.html

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    About Author

    melypr1985
    Meredith Presley started keeping marine aquariums in 2007. She’s done everything wrong that can be done in the hobby (mostly but not all in that first year) and that has afforded her to learn a lot of hard lessons. Recently she’s been focused on marine disease diagnosis and treatment and hopes to focus on breeding soon as well. She also keeps a blog with basic info on saltwater keeping and her experiences with her own tank and livestock.
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