Animal communication is an open secret. They are sending signals out in the open but we have no way of comprehending these signs that are all around us. (See entomology of "comprehend": com- "completely" (see com-) + prehendere "to catch hold of, seize", see prehensile)In other words, we had no idea why the Tarsier primate open and closed its mouth from time to time. Nor did we understand why arctic Snowy Owls would turn their feathers at a particular angle to the sun. Only recently have we discovered that they are communicating, sending out signs and waves. What other animal communication goes unknown and unnoticed by us? The earth (and indeed the universe) is replete with languages and meanings. Listen he who has ears to hear.
"these tiny primates can send and receive ultrasonic calls, joining a select club of mammals with the same acoustic talent—namely, whales, dolphins, cats, rats and bats. Researchers already knew that tarsiers make at least 15 distinct calls—all of which are audible to people—but until now no one had good evidence that they also communicate with ultrasonic shrieks"