Zond 5 launched on 15 September 1968 and swung around the Moon before splashing down in the Indian Ocean on 21 September. The biological payload included two steppe tortoises, along with wine flies, mealworms, plants, seeds and bacteria, chosen partly because tortoises tolerate long periods without food and need little life support.
The animals were recovered alive. Reports noted they had lost roughly a tenth of their body weight but remained active and feeding, with no obvious effect attributed to the flight itself.
The first crewed lunar flight, Apollo 8, followed in December 1968. The tortoise flight is often described as sending the first animals around the Moon, which is accurate, but it is sometimes stretched into a claim about the first animals in deep space, which it was not: earlier missions had carried living organisms beyond low Earth orbit.