Please answer the following question: Pick one category for the following text. The options are - company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work. Tetrapulmonata -  Tetrapulmonata is a non-ranked supra-ordinal group of arachnids. It is composed of Thelyphonida Schizomida Amblypygi and Araneae. It is the only supra-ordinal group of arachnids that is strongly supported in molecular phylogenetic studies.
Answer:
Animal