In this episode of NOVA’s Gross Science, Anna Rothschild introduces us to the carnivorous fanged pitcher plant (Nepenthes Bicalcarata) that preys on unsuspecting insects, but has a special relationship with one particular species of a ‘diving’ ant that’s endemic to Borneo: Camponotus Schmitzi. From Wikipedia:
Nepenthes bicalcarata is a myrmecotroph (ant-fed plant), obtaining nutrients from C. schmitzi in the form of egesta and, occasionally, ant remains. It has been estimated that this input accounts for 42% of the plant’s total foliar nitrogen (76% in plants with ant occupancy rates above 75%).
The ants increase nutrient retention in the pitchers by preying on infaunal flies, which would otherwise eventually leave their hosts and thereby act as kleptoparasites. This nutrients later becomes available to the plant through the ants’ waste. Camponotus schmitzi has also been observed to attack newly caught insects and therefore prevent prey escape. At other times, the ants are very passive, remaining hidden under the inner peristome fold, presumably so as not to dissuade visitation by potential prey species.
There are a few other video examples of symbiosis in the archives.