As we know, sharks have been in existence for over 500 million years. From an evolutionary perspective of vies, they are among the oldest animals with a “modern” immune system not unlike that of humans. Shark blood contains large quantities of urea that makes their antibodies much more robust than that of other vertebrates. While urea protects sharks from dehydration, it can also destabilize sensitive protein molecules such as antibodies. https://www.creative-biolabs.com/blog/index.php/native-shark-antibody-discovery-used-in-shark-monoclonal-antibody-production/