Animal researchers and zookeepers have been key resources for Linden's appreciation of animal intelligence. One zookeeper describes elephants that seem to cooperate intelligently in their own foot care, as well as engage in meaningful communication. A veteran observer of killer whales claims that this species also has the capacity to communicate and suggests that whale families even have their own dialects. She uses a hydrophone to record whale communication and identify the specific sounds associated with specific activities. A family of whales, she claims, was instrumental in directing her to safety after she became lost in a dense fog. Orangutans also seem to demonstrate complex mental abilities. They are notable for being escape artists. They have also shown the capacity to tolerate painful needles, apparently because they recognize that the needles are good medicine. No orangutan is more legendary than the now deceased Fu Manchu. He hid wire in his mouth until just the right time to pick the lock on his enclosure. Indeed, all manner of thought has been observed in all manner of animals.