Avatars are traditionally understood as representing their human counterparts in virtual contexts by incorporating many aspects of a person's real world physical characteristics within the virtual form. An alternate approach, in which avatars are instead imbued with non-human characteristics, challenges the limitations of solely anthropomorphic principles and expands the potential of avatars for virtual world interaction and communication. This paper provides a brief history of nonanthropomorphic avatars, with a focus on exploring the current use of such avatars in virtual worlds. In order to explain the shift in degree of anthropomorphism, we discuss Goffman's theory of symbolic interactionism, which holds that the self is constructed as a persona through social performance and relates identity to social behavior rather than appearance. Since nonanthropomorphic avatars are persistent characters engaged in a prolonged performance in virtual worlds, their use also may motivate emerging social mores, politics and ideologies. This paper argues that such avatar species create new social interactions and modes of communication that may signal interesting directions for future research.