|Out of universe information|
The "Pod people" are a race who, on the outside, appear to be fairly human, but with a unique internal anatomy. The species has no apparent communication other than an unusually pitched "singing", which seems to connect with the flora around them. They do not use gestures or body language to relay ideas or communicate by any means. Dr. Jackson, in his honesty, claimed to have more successful conversations with dogs. Following this comment he admitted, appearances aside, the race was probably less advanced than the Tau'ri.
Still, the inhabitants remained curious of SG-1, and their rudimentary ways did not lend themselves to hostility. In fact, they were perfectly willing to let the team help when things began to fall apart.
The creatures are concealed by the thick, paint-like material they adorn over their entire body. An internal organ in the chest was unidentifiable by Dr. Fraiser, but she suspected it was super-sensitive to subtle changes in sound. An ultrasound on one of the creatures sent it into a panic.
When the plant life on PJ2-445 was disturbed by the crash of a U.A.V., the damage to the plant changed the pitch across the area for a radius of at least six miles, "injuring" the humanoid creatures, forcing many to go unconscious. Because of a thick-coated paint over their bodies and their distinctly inhuman internal anatomy, SG-1 was unable to determine whether or not they had a pulse or, for that matter, a heartbeat.