Japanese dwarf flying squirrel
|Japanese dwarf flying squirrel|
Its body is 14–20 cm long and the tail length is 10–14 cm. It weighs 150–220 g. It is much smaller than the Japanese giant flying squirrel which can reach 1500 g. Its back is covered with grey brown hair, and its belly is white. It has large eyes and a flattened tail.
It inhabits sub-alpine forests in Japan. It is nocturnal, and during the day it rests in holes in trees. It eats seeds, fruit, tree leaves, buds and bark. It can leap from tree to tree using a gliding membrane called the patagium. The patagium works as a wingsuit enabling it to maneuver and glide through the air.
When it feeds, the Japanese dwarf flying squirrel assumes a hanging posture. It will pull a twig to its mouth with its forepaws if the twig is not strong enough to support its weight and obtain food at the tip. While picking up food scattered on the ground, it will extend its body in an intermediate range around its body without moving its hind legs.
Japanese dwarf flying squirrels make their nests in the cavities of tree trunks. Tree cavities are very important nest resources for them. They tend to nest in conifers more than broad-leaved trees.
Japanese dwarf flying squirrels have evolved differently from other sciuridae. The differences between Japanese dwarf flying squirrels and other sciuridae is evident when comparing morphology of the mandible and genetic code. The mandible of the Japanese dwarf flying squirrel does not have a coronoid process unlike the dwarf tree squirrel. The marmota also has a more elongated mandible than the Japanese dwarf flying squirrel. This is due to phylogeny and ecology. There are even differences in genetic code within the same species. Pteromys momonga and Pteromys volans have the same number of chromosomes, but their karyotypes differ. The karyotypic differences resulted from pericentric inversion, tandem fusion, and deletion of autosomes and the Y chromosome. Pteromys volans genome contains about fifteen percent less DNA than Pteromys momonga. This is because of deletions in P. volans karyotype. These findings suggest that the karyotype of P. momonga is ancestral and that P. volans is derived from it.
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