Adult dragonflies live near healthy bodies of water, such as streams, lakes, ponds and waterfalls. Antartica is the only continent not inhabited by dragonflies. They belong to the scientific order Odonata, which means toothed, referring to the dragonflies' toothed jaws. Male dragonflies are aggressive mates, and are often guilty of sexual harassment. Their breeding habits can be violent and dangerous. There are more than 6,000 dragonfly species.
The Physical Characteristics of Dragonflies
Dragonflies have long, slender bodies that vary in color and are frequently metallic. Their long, slender wings are interlaced with veins. Some dragonflies have banded wings. They have large compound eyes and grasping mouthparts that protrude. Females are smaller and thinner than males. When resting, damselflies hold their wings over their backs. Males spread their wings out when they're at rest. Males have two sets of sexual organs; their testes is located at their abdominal tip, with a tiny penis and a small sperm-storing pouch at their abdominal base.
Sex and Violence
Male dragonflies are violent breeders, sometimes splitting up mating pairs by biting, ramming and pulling the couple. Some males simply snatch up an unsuspecting female, roughly grasping her head or thorax, and often inflicting injuries. The damselfly fiercely fights back, flying in zigzags, spirals and dives as she attempts to escape the offending dragonfly.
Self-Insemination and Mating
The male dragonfly must inseminate himself, first transferring sperm from his testes to his sperm pouch, then placing the sperm into his penis before mating. During flight, the dragonfly grips the damselfly's head behind her eyes, and she bends her abdominal tip to meet his penis. He scrapes away any sperm the female may be carrying from a previous male before he inseminates her. The male often guards the female after mating, remaining in tandem with her or staying nearby, until her eggs are laid.
From Egg to Nymph
Most damselflies immerse their abdomens along the water's surface, depositing their eggs into the water. Some will lay their eggs in the mud or algae along the water's edge or on plants draped over the water. Females will lay dozens, or possibly hundreds, of eggs. No parental care is provided after the eggs are laid. Most dragonfly eggs hatch in one to three weeks, but some species can overwinter. The hatching larvae are aquatic nymphs.
From Nymph to Adult
Living under water, a dragonfly nymph breathes using tracheal gills located in his rectal chamber. His larval stage can last from a few months to several years. Eating tiny marine organisms, the larva may molt up to 15 times during his growth stage. When the nymph reaches adulthood, he crawls from the water, clutching onto a branch or rock. His larval skin splits, and the adult dragonfly emerges. He is sexually mature within a few days or weeks. The average adult dragonfly will live for six to eight weeks.
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