Ants: Ant colonies on the green planet expand, adapt, and develop new castes without individual thought. Spiders first encounter them as a threat, then use colonies for work and technology.
Humans: Humans built the Old Empire, lost it in a war and left Earth for good. On the green planet the spiders know them as the Star Gods and expect them to return as destroyers.
Monkeys: Ten thousand primates were carried in the Brin 2's Barrel as stock for Kern's uplift experiment, and burned with it in the atmosphere of the green world. The word then becomes Kern's name for the people she thinks she is uplifting, and her insult for humans.
Paussid beetles: Small dark red beetles that live inside ant nests and read as nothing at all to their hosts. Bianca turns their scent of absence into armour and into the gas that stops the ant column marching on Great Nest.
Scytodes pallida: A spider with long legs and a hunched body that spits sticky, venomous webbing to catch jumping spiders. Portia's kind call them the Spitters, raise them as one of the planet's thinking neighbours, and never wipe them out.
Spiders: Descendants of Portia labiata develop intelligence and a complex society under the influence of a nanovirus. They preserve knowledge through inherited Understandings and later share their world with humans.
Stomatopods: A crustacean people of the western ocean, in cautious and mostly minimal contact with the spiders of Great Nest. Mathematics is the one subject the two species discuss with any ease.