RARE SPECIES can be considered as such when they have small population sizes, narrow habitat ranges, and intolerant to environmental changes. They possess ecological and taxonomic-evolutionary repercussions. They are challenging to sample and interpreted when obtained. The rarity of a specimen can be attributed to methodology, disturbance, seasonal natural phenomena in relation to climate, vegetation, and interaction with other animals. It is also inferred that rare species’ small population may be the typical characteristic of a tropical species that is prevalent in the country. Oftentimes when sampling, about a quarter of the samples could be single specimen of different species. It is most probable that many described species are known only from single unique type specimens. Some rare species may exhibit unstable capability to ecosystem variability. They may compensate for the loss of a dominant animal species which may be taken over by rare ones to maintain ecological function.