In the Genesis account of Noah’s Ark, one pair of each unclean animal entered the ark. Genesis 7:2 distinguishes between animals considered clean and unclean, instructing Noah to take seven pairs of clean animals but one male and one female of unclean animals.
This detail is easy to miss because many simplified retellings say only that animals entered “two by two.” That phrase captures the male-and-female pairing but does not include the text’s different numbers for clean and unclean animals.
Genesis 7:8–9 summarizes animals going into the ark in pairs, while the earlier instruction provides the fuller distinction. The wording also reflects the ritual categories used in the biblical text; it is not a modern zoological classification.