Symbiosis is the condition in which different organisms live together and show spatial and
temporal overlap in their interactions. The consequences of such interactions may be
beneficial. detrimental, or neutral; their nature often depends on ecological and
environmental contexts and may result inter alia in mutualistic,parasitic,commensal,
antagonistic, or neutral relationships.
Symbiotic associations with microorgenisms are found ubiquitously across the animal
kingdom,For example, many corals are capable of photosynthesis despite their animal
nature, owing to endosymbiotic dinoflagellate algae. Tubeworms gathering around
hydrothermal vents in the oceanic floor possess neither mouth nor anus. and live exclusively
on metabolites supplied by the huge amount of chemoautotrophic bacterial endosymbionts
residing in their bodies. Some sponges and beetles defend themselves against predators by
making use of poisonous polyketide compounds produced by symbiotic bacteria. Termites
possess rich symbiotic microbiota in their highly-developed hindgut, wherein woody food
materials consisting mainly of cellulose and lignin are digested by cellulolytic activities of the
symbionts, In aphids and many other insects, endosymbiotic bacteria provide their hosts
with nutritional components that are deficient in hosts'food sources. The majority of millions
of insect species are associated with bacterial endosymbionts of the genus Wolbachia, which
can affect host reproductive modes in a variety of ways.
Given the ubiquity and the importance of symbioric microorganisms in animals, it is
unsurprising that the general zoological journal Zoolocial Science has published a number
of papers dealing with animal-microbe symbiotic associations over the years. In this virtual
issue, I have compiled 38 relevant papers published in the journal sice 1995. Here four
animal taxa, namely tunicates, corals, ciliates and insects, are preferentially represendted. This
pattern does not reflenct the real diversity of animal-microbe associations, but rather reflects
the concentration of researchers working on these research subjects. There are doubtless
many more fascinating animal-microbe symbiotic associations that await future discovery
and investigation