The aliens are extremely light sensitive, causing them to squeal in agony when confronted with the flash light of a photographic camera for example. Exposure to extreme brightness can cause them to literally explode. Their body parts (at least the hands) are known to remain alive for extended periods after being thorn out, and not only continue to move but apparently even make rational decisions such as ambushing and attacking. This implies that either their nervous system is not fully cephalized, or they are somehow able to keep control of severed body parts by psychic means, even over long distances.