Effects of miniaturization in the anatomy of the minute springtail Mesaphorura sylvatica (Hexapoda: Collembola: Tullbergiidae)статья
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Дата последнего поиска статьи во внешних источниках: 23 января 2020 г.
Аннотация:Smaller animals display pecular characteristics related to their small body size, and
miniaturization has recently been intensely studied in insects, but not in other
arthropods. Collembola, or springtails, are abundant soil microarthropods and form
one of the four basal groups of hexapods. Many of them are notably smaller than 1
mm long, which makes them a good model for studying miniaturization effects in
arthropods. In this study we analyze for the first time the anatomy of the minute
springtail Mesaphorura sylvatica (body length 400 mm). It is described using light and
scanning electron microscopy and 3D computer reconstruction. Possible effects of
miniaturization are revealed based on a comparative analysis of data from this study
and from studies on the anatomy of larger collembolans. Despite the extremely small
size of M. sylvatica, some organ systems, e.g., muscular and digestive, remain complex.
On the other hand, the nervous system displays considerable changes. The brain has
two pairs of apertures with three pairs of muscles running through them, and all ganglia
are shifted posteriad by one segment. The relative volumes of the skeleton, brain, and
musculature are smaller than those of most microinsects, while the relative volumes
of other systems are greater than or the same as in most microinsects. Comparison
of the effects of miniaturization in collembolans with those of insects has shown that
most of the miniaturization-related features of M. sylvatica have also been found in
microinsects (shift of the brain into the prothorax, absent heart, absence of midgut
musculature, etc.), but also has revealed unique features (brain with two apertures and
three pairs of muscles going through them), which have not been described before.