Here at the San Diego Zoo, we are uniquely situated to introduce the concept of biomimicry in an engaging, hands-on way using the thousands of species in our collection. Educational programs at the Zoo are teaching and inspiring students, and the expertise of our scientists, curators, horticulturists, veterinarians, and others is helping to guide entrepreneurs, investors, and companies to find sustainable solutions to design problems by looking to the animals and plants right here at the San Diego Zoo and San Diego Zoo Safari Park. With all the ways that the Zoo is using biomimicry to change the way that people approach challenges in business, we don’t often stop to think about how biomimicry has impacted our own efforts to conserve endangered species. As it turns out, we have learned a lot about how to conserve nature from nature!
Cryopreservation, the process where cells or whole tissues are preserved by cooling to sub-zero temperatures, is a technique that the San Diego Zoo Institute for Conservation Research utilizes daily. After all, we do house the world’s most diverse collection of frozen sperm, egg, and cell lines in a collection we call the Frozen Zoo®! This collection of cells represents more than 700 species of animals, from mammals like rhinos and tigers to reptiles and amphibians. Specimens in the Frozen Zoo can be stored indefinitely and used for procedures such as artificial insemination, in vitro fertilization, embryo transfer, and cloning.
This process of freezing cells to preserve them is pretty complicated! It requires a lot of work protecting the cells first, so that ice crystals won’t form and break open the cell membrane, and our scientists work hard to develop protocols for each animal’s cells. Many animals in nature have their own protocols for surviving at sub-zero temperatures. The wood frog Rana sylvantica is distributed throughout North America, including northeastern Canada and Alaska. As with other species of frogs that live in cold climates and hibernate close to the surface in soil or leaf litter, the wood frog can actually survive freezing! The frog starts storing urea and glucose in its tissues in preparation for winter, where these two compounds act as natural cryoprotectants that reduce ice crystals and osmotic shrinkage of cells.
The larvae of the Alaskan beetle Cucujus clavipes puniceus can survive up to -100 degrees Celsius (-148 degrees Fahrenheit) by using the freeze-avoiding compound glycerol. Our scientists have been able to learn from these “experts” in the field to perfect cryopreservation, thereby ensuring that we will have this indispensable resource for generations to come.
Robin Keith is a senior research coordinator at the San Diego Zoo Institute for Conservation Research. Read her previous post, Go Play Outside!