Angel Insects
Zoraptera
Summary 4
The insect order Zoraptera, commonly known as angel insects, contains a single family, the Zorotypidae, which in turn contains one extant genus with 39 species, Zorotypus as well as 9 extinct species. They are small and soft bodied insects with two forms: winged with wings sheddable as in termites, dark and with eyes (compound) and ocelli (simple); or wingless, pale and without eyes or ocelli. They have a characteristic nine segmented beaded (moniliform) antenna
Behavior and ecology 5
They live in small colonies beneath rotting wood, lacking in mouthparts able to tunnel into sound wood, eating fungal spores and detritus but also can hunt smaller arthropods like mites and collembola.
Zorotypus gurneyi lives in colonies consisting of up to several hundred of individuals. Most commonly the colonies have a size of around 30 individuals, of which about 30% are nymphs, the remainder adults. Zoraptera spend most of their time grooming one another. The grooming process is thought to be a way of removing fungal pathogens.
When two colonies of Z. hubbardi are brought together experimentally, there is no difference in behavior towards members of the own or new colony. Therefore, colonies in the wild might merge easily. Winged forms are rare. The males in such average colonies establish a linear dominance hierarchy in which age or duration of colony membership is the prime factor determining dominance. Males appearing later in colonies are at the bottom of the hierarchical ladder, regardless of their body size. By continually attacking other males, the dominant male monopolizes a harem of females. The members of this harem stay clumped together. There is a high correlation between rank and reproductive success of the males.
Z. barberi lack such a dominance structure but display complex courtship behavior including nuptial feeding. The males possess a cephalic gland that opens in the middle of their head. During courtship they secrete a fluid from this gland and offer it to the female. Acceptance of this droplet by the female acts as behavioral releaser and immediately leads to copulation.
In Z. impolitus, copulation does not occur, but fertilization is accomplished instead by transfer of a spermatophore from the male to the female. This 0.1-millimetre (0.0039 in) spermatophore contains a single giant sperm cell, which unravels to about the same length as the female herself, 3 millimetres (0.12 in). It is thought that this large sperm cell prevents fertilization by other males, by physically blocking the female's genital tract.
Sources and Credits
- (c) Angal insect, some rights reserved (CC BY-SA), http://commons.wikimedia.org/wiki/File:Zorotypus.jpg
- (c) Robby Deans, some rights reserved (CC BY-NC), uploaded by Robby Deans
- (c) Joshua Doby, some rights reserved (CC BY-NC), uploaded by Joshua Doby
- Adapted by Will Kuhn from a work by (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Zoraptera
- (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Zoraptera
