Wet/Fluid Preserved

Traditional methods of specimen preparation often meant that only the skin, and perhaps skeleton, of a specimen was prepared and curated into museum collection. This meant that the musculature, organ systems, and other soft tissues of a specimen were often discarded. However, new and developing research techniques requiring more of the specimen are becoming increasingly important. In that respect, our collections have been making more whole fluid-preserved or 'wet' specimens. This entails the 'fixing' or initial preserving of a specimen in formalin or ethanol, then storing it in a jar of ethanol for long-term curation. The result is the preservation of a complete specimen with all of the original anatomical structures, both internal and external, entirely intact. This allows for examination of organs and other soft tissues, as well as its plumage, by researchers who study such aspects as biomechanics, diet & feeding ecology, reproductive biology, adaptive physiology, comparative anatomy, and parasitology.


The most common, and perhaps most traditional, way of preparing a bird or mammal specimen for long-term curation is as a study skin. This basically means that the internal organs, musculature, and most of the skeleton of the specimen have been removed, and the internal body cavity filled with cotton. This method leaves the complete outer skin with fur or feathers, along with the distal portion of the legs and feet, the distal limb bones, and the anterior skull with the beak (if it's a bird); if the specimen is a mammal, usually the terminal foot bones remain in the skin. When the skin is prepared, the aim is to maintain the original shape and size of the original specimen. In most cases, the wings are folded against the body as the bird would when resting, or the limbs of a mammal are extended. However, some newer preparations leave the wing extended so that the feathers and feather tracts can be seen more easily. In some cases where a specimen is not suitable for a complete study skin, sometimes just the spread-wing and or tail is prepared, with the rest of the specimen being prepared in a different manner, such as a skeleton.


The Department's collection of bird and mammal skulls and skeletons is extensive, and our collections of mammalian postcranial skeletons are of particular importance. Often in conjunction with preparation of a study skin or pelt is the preparation of the specimen's skeleton. In mammals, it is possible to prepare a study skin and extract a nearly complete skeleton, but in birds, preparation of a study skin leaves an incomplete skeleton. Even incomplete skeletons are valuable, and are usually prepared. If some specimens are damaged or would otherwise not make good study skins or pelts, they often become complete skeletal preparations. During the course of preparation, the skeleton often comes apart and the bones are disassociated from each other. This is called a disarticulated skeleton, and is particularly useful when scientists need to study individual bones from an animal. If the preparation procedure results in the bones being connected in their original order, that is called an articulated skeleton. Such a specimen allows scientists to study the interrelationships of bones as a complete skeletal structure, and to better understand the skeleton as a mechanical system. Bones are essential tools for those who study systematics, biomechanics, evolutionary morphology & adaptation, paleontology, and identification of animal remains from archeological sites.

Contact the Collections Manager

For inquiries please contact:

  • Maureen Flannery (Moe)
  • Collections Manager
  • California Academy of Sciences
  • 55 Music Concourse Drive
  • San Francisco, CA 94118
  • 415-379-5371 (direct)