a sequence of organisms in a community each of which uses the next usually lower member of the sequence as a food source, plants being the ultimate basis of the sequence, organismidevaheline toitumissuhtestik; toiduahela esimese astme moodustavad autotroofid (produtsendid), teise taimtoidulised (herbivoorid), kolmanda lihatoidulised (karnivoorid) jne