Spider nursery Mammals produce milk to feed their offspring, and maternal care often continues well after the young can forage for themselves. Though other cases of milk-like secretions have been found, this combination of ongoing maternal care has largely been considered a uniquely mammalian trait. Chen et al. describe an ant-mimicking jumping spider that secretes a nutritious milk-like substance on which its young offspring are entirely dependent. The spider also continues to care for the spiderlings as they mature and become independent. Thus, this type of maternal care may be more widespread than has been assumed. Science , this issue p. 1052