Nile crocodile stability and additional weight to sink in water, this bearing great probability over the theories that they assist in digestion and staving off hunger. However, Alderton (1998) stated that a study using radiology found that gastroliths were seen to internally aid the grinding of food during digestion for a small Nile crocodile. Herodotus claimed that Nile crocodiles have a symbiotic relationship with certain birds, such as the Egyptian plover ("Pluvianus aegyptius"), which enter the crocodile's mouth and pick leeches feeding on the crocodile's blood, but no evidence of this interaction actually occurring in any crocodile species has been found, and
Symbiotic bacteria endonuclear symbiotic bacterium Holospora, it has been discovered that Holospora species can maintain their infectivity for a limited time and form a symbiotic relationship with Paramecium species. It is well accepted and understood that there is a mutualistic relationship between plants and rhizobial bacteria and mycorrhizal fungi enabling the plants to survive in an otherwise nitrogen-poor soil environment. Co-evolution is described as a situation where two organisms evolve in response to one another. In a study reported in "Functional Ecology", these scientists investigated whether such a mutualistic relationship conferred an evolutionary advantage to either plant or symbiont. They did not