Leaf cutter ants at Bristol Zoo carry heart-shaped rose petals, as florists prepare for their busiest weekend of the year. Around nine million roses are given on Valentine’s day. The ants can carry loads of up to 20 times their body weight – the equivalent of a human lifting a ton. They do not live on the leaves themselves but cultivate a compost from collected plant material on which a fungus grows that they then eat. The ants were provided with the pink rose petals as part of an ongoing enrichment programme at the zoo.