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Smithsonian National Museum of Natural History
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Division of Amphibians & Reptiles

Destructive Analysis

While the Smithsonian National Museum of Natural History exhibition spaces will partially open to the public on June 18th, our collections remain closed to most staff and all researchers, and the museum’s COVID-19 loan moratorium remains in effect. Currently, there is no capacity to accommodate collections activities including visits, image requests, loans, and shipments.  While there is no current date set for when on-site collections activities will resume, we will update as soon as this changes.

Destructive analysis of USNM specimens (including dissection, clearing and staining, tissue sampling from morphological specimens, and use of specimens for diffusible iodine-based contrast-enhanced (diceCT) scans) requires the written approval of an USNM curator. 

Permission to modify one specimen is not automatically conferred to other specimens.  When in doubt about terms of use, ask Division of Amphibians and Reptiles staff.

Requests for destructive analysis can be submitted with an initial loan request per Division of Amphibian and Reptile instructions. Destructive analysis request addenda for specimens already on loan must be submitted to a USNM curator for review.

On site visitors to the collection must also receive the written approval of a USNM curator prior to alteration of specimens. 

Bottom line, specimens cannot be altered in any way without the written approval of a USNM curator.

When permission for sexing specimens has been given, incisions must be performed to avoid cutting skeletal elements and viscera; incisions should be kept as small as possible.

  • Anurans:  incision on dorsolateral body wall, adjacent to the sacral diapophysis.
  • Salamanders & Lizards:  midventral incision beginning midbody (but posterior to stermal elements including inscriptional ribs, extending posteriorly to pubes, here a lateral incision on one side is permitted.
  • Snakes, Amphisbaenians, & Caecillians:  short midventral incision over the gonad region; do not extend incision from vent forward to midbody.  If incision remains open, close with 1 or 2 suture stitches.  If a snake is sexed by hemipenial dissection, the incision should be made to locate only one hemipenis.

We consider sampling tissue from morphological specimens (e.g., ethanol preserved or formalin-fixed specimens, dry skin samples, dry tissue off bones) for genetic resources a destructive sampling request, which requires approval of all curators. Requests for these types of genetic resource loans should include the following data points in addition to the general request criteria outlined for genetic loans. 

  • Additional explanation of why the destructive sampling is necessary to meet the objectives of the research.
  • Description of methods for DNA extraction from formalin-fixed materials and sequencing.
  • Experience of the researchers with the proposed techniques.

The Division of Amphibians and Reptiles lends specimens from its research collections for computed tomography and other imaging scans for scientific and educational purposes that are consistent with the curatorial policies of the Division and with the goals and objectives of the National Museum of Natural History and the Smithsonian Institution. 

Guidance and terms of use of specimens for computed tomography and other imaging processes is provided in a detailed overview.