The purpose of this research was to explore and compare the ideas of Saudi boys and girls on animal species. Eighty-four children (comprising 42 boys and 42 girls), aged nine years, from four primary schools, participated in structured interviews to determine their ideas pertaining to taxonomic labels, namely 'animal', 'fish', 'amphibian', 'reptile', 'bird', 'mammal', and 'insect'. The results demonstrated that Saudi children of both genders display a wide range of alternative conceptions; more specifically, the effect of gender was significant for all taxonomic vertebrate labels, suggesting that Saudi boys have better knowledge relating to animals than girls. However, generally, children did not have adequate forms of reasoning for biological classification. It was also found that none of the fourth graders thought of humans as animals due to the Islamic science worldview. Based on these findings, it is argued that science education, notably in an international context, should strive to incorporate an understanding of local values and beliefs.