The streams of Trinidad and Tobago are home to the most unexpected of landscape gardeners. They're guppies - tiny and beautifully coloured fish, just an inch or so long. Without tools or plans, they shape the environment around them, tweaking everything from the numbers of different species to the nutrients in the water.
The guppies are quick to adapt to different environments and particularly to which predators are around. The number and types of predators affect the guppies' lifespan, how big they get and when they become sexually mature. This, in turn, affects what they eat, and that influence ripples across the entire stream.
