Although we've documented thousands of species, we've yet to discover them all. Some argue that only small species have yet to be discovered or microscopic ones, because if such large animals existed they'd have already evidenced themselves. But in the past 10 years, science has documented a variety of new species, including the Hoan Kiem Turtle (Rafetus leloii) and Homo floresiensis, a potential descendant of the earlier Homo erectus (upright man).

The field of science devoted to discovery of these new species, cryptozoology, literally means hidden animals. It's the study of and search for living animals taxonomically identified through fossil records, but believed to be extinct, as well as, those for which a lack of empirical evidence precludes taxonomy, but whose existence has been documented in the form of myths, legends, or laymen's sightings. Cryptozoology's interdisciplinary approach using both the scientific method and data from fields such as anthropology and geography make it an integrated science.

Although cryptozoological discoveries often draw great attention, the field composes a tiny sub-discipline of zoology. Although few scientists doubt thousands of unknown animals exist, few devote themselves to the search for them. Historian Mike Dash points out that cryptozoologists seem largely uninterested in researching and cataloguing species of ants or beetles. Instead, he states they research "more elusive" species, such as those referred to as megafauna cryptids, the larger unknown species many of which are only suspected to exist due to continued laymen sightings following initial anthropological documentation in the form of a myth or storytelling.

Some famous, yet unproven megafauna cryptids include Sasquatch, the Yeren, and the Loch Ness Monster. But fame and mythic status does not preclude discovery. Before empirical evidence amassed for its existence between the years 1998-2002, the Hoan Kiem Turtle was documented only in Chinese mythology. Now two representatives of the former cryptid, which can grow to six feet and top 400 pounds, reside in zoos in China, while another still swims the waters of Hoan Kiem Lake.

Water provides an ideal hiding place for shy species, so the oceans also provide ample research opportunities for cryptozoologists. In 1976 a new shark species, the megamouth (Megachasma pelagios) was discovered off the coast of Oahu, Hawaii, USA when it became entangled in the anchor of a U.S. Navy ship. Since its discovery 32 years ago, 41 specimens have been captured or sighted and the animal has been documented on film three  times. Before its initial accidental capture it was consistently sighted, but the sightings were ignored or attributed to another animal.

Though its a small field, cryptozoology is far from fringe science, and a number of professional and scholarly organizations support it, such as the British Columbia Scientific Cryptozoology Club, the International Society for Cryptozoology and the Centre for Fortean Zoology. Although it is tempting to turn to the Internet for information, some sites devoted to the topic may seem to provide reliable information at first blush, but are actually filled with inconsistent and incorrect information. For instance, the articles area on cryptozoology.com has an introductory article on cryptozoology with no basis in reality, beginning with its erroneous statement that it is not an area of science. Others provide reliable, useful references lists, including recommended books and films, such as PibBurns.com.