Smithsonian National Zoo Offers Mysteries and Opportunities

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Story by Abbey Stoetzel

The Smithsonian National Zoo in Washington D.C. is home to over one thousand animals. That number, however, is decreasing due to the close of the Invertebrates Exhibit last June.

“There was some assessment done in terms of cost and something had to give and we got the short straw. You got the sense that something was coming. We all sort of have to move on from it. It’s unfortunate,” said Alan Peters, Curator of the Reptile House.

The Smithsonian National Zoo in Washington D.C. homes over 1,000 animals. This past June, the Invertebrates Exhibit was closed permanetely. Photo by Kayla Uhl
The Smithsonian National Zoo in Washington D.C. homes over 1,000 animals. This past June, the Invertebrates Exhibit was closed permanetely. Photo by Kayla Uhl

Peters is the former Curator of the Invertebrates Exhibit.

“I actually started here in 1978 as a volunteer in graduate school. It’s nice to circle back. I poured my heart into the invertebrates. It’s a hard transition but good things are to come,” said Peters.

Peters, along with other former workers of the Invertebrates Exhibit, have closely watched one certain marine animal: the nautiluses. The nautiluses have grown in popularity through the science world and have grown the interests of many people.

“It’s not a recent thing in terms of a new issue but it’s new in that there have been periods of time where nautiluses have been researched and we were seeing an increase of attention on nautiluses. We were hoping to go with that wave,” said Peters.

A nautilus is a cephalopod that lives in tropical waters. Unchanged in the wild since its first appearance 500 million years ago, nautiluses are changed when put into captivity. The white shell begins to crack and then turn black when in captivity.

“The mantle tissue lays down the shell. As it lays down the shell, apparently the crystalline structure or the calcium carbonate isn’t as organized as it is in the wild,” said Peters. “So it’s irregular, rough, and doesn’t have the same coloration as it does in the wild. That’s generally not an issue or problem, but it can deform enough, [and] it’ll start to curl back. Then that becomes an issue because the animal lays down on the septum that gives the chamber and it could prevent making the next chamber which would be a problem because it can’t grow. But that’s rarely the issue.”

When a nautilus is put into captivity the shell begins to crack and turn to black. Scientists continue to research as to why this happens. Photo by Kayla Uhl
When a nautilus is put into captivity the shell begins to crack and turn to black. Scientists continue to research as to why this happens. Photo by Kayla Uhl

The mystery behind this deformation is that every nautilus ever brought into captivity has changed, and no scientist has ever found out why the coloration happens.

“I think it’s the crystalline forming of the calcium carbonate [and] it isn’t the same. I think it’s mostly impacted by the temperature and pressure and the movement,” said Peters.

Changes to animals in captivity may raise the question to some if animals should be kept in captivity at all.

“I think it very much depends on the space they’re given and whether the environment is appropriate for them to have a full life and development. It’s very difficult to know why they’re changing. I don’t think anybody knows. I think if they’re being fed a good diet and have enough space to move around the way they’re supposed to, I think it’s okay,” said Melitta Carter, who has been a volunteer at the zoo for ten years, and currently volunteers in the Amazonia exhibit.

Peters, along with other researches, has tried many experiments to find the reason behind the change in captivity.

“We did an earlier project where we were wiping it down and doing bacterial tests to see if that was and there was some indication that just the physical scrubbing of the shell on some regular basis improved but I really think what it was doing was cleaning bacteria off to some extent but it was probably just knocking not some of the very sturdy shell off. I don’t think that’s a real solution because it doesn’t change the way it lays down,” said Peters.

In a recent article written by John Barrat for Smithsonian Science, Barrat states that “The researchers next plan to conduct experiments measuring the impact of temperature and light on the production of black areas of shell, as well as the function of proteins in wild vs. captive  shell production.”

Research at the zoo itself, however, has slowed due to the Invertebrates Exhibit closing.

“There are some researchers that are at other facilities that have our shells so we’re going to continue that research but working with the live animals, at this point, we won’t be able to do,” said Peters.

Even though the Invertebrates Exhibit is no longer available, Peters still hopes that nautiluses will appear at the zoo in the future.

“The hope is that there is ever an exhibit that talks about BioDiversity but that will be many years off and potentially they could be part of that,” said Peters.

For more information on nautiluses, visit nationalzoo.si.edu.

 

 

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