I noticed that occasionally a larva would climb out of the water onto a rock, and that this was a. Shifting from ventilating a rectal gill with water to ventilating a tracheal system with air is also associated with a change in how abdominal ventilation is controlled nymphs regulate gas exchange by varying frequency while imagoes respond by varying amplitude.Īmphibious Aquatic Dragonfly Hypercapnia Hypoxia Ventilation.Ĭopyright © 2017 Elsevier Ltd. Dragonfly larvae are excellent indicators of mercury risk because they can live for years underwater eating insects and even small fish. In particular I was fascinated by the dragonfly larvae. These results demonstrate that aquatic dragonfly nymphs possess a respiratory sensitivity that is more like other water breathing animals, being sensitive to hypoxia but not hypercapnia, while their air-breathing adult form responds to both respiratory challenges, like other terrestrial insects. In contrast, both species of air-breathing imago increased their abdominal pumping amplitude when exposed to either hypoxia or hypercapnia, but did not show any significant increase in frequency. The nymphs are important food for fish, frogs, and other aquatic insectivores. They and the adult forms are important predators of mosquitoes, midges and other small insects. Some species live for 5 years underwater before becoming adults. Water-breathing nymphs showed a significant increase in abdominal pumping frequency when breathing hypoxic water (<10 kPa O 2), but no strong response to CO 2, even in severe hypercapnia (up to 10 kPa CO 2). Most of a dragonfly’s life is spent as a nymph. In this study, dragonfly nymphs (Anax junius) and imagoes (Anax junius and Aeshna multicolor) were exposed to hypoxia and hypercapnia while their abdominal ventilation frequency and amplitude was recorded. Extract from 'Secrets of Pilanesberg'Extract from 'Secrets of Pilanesberg'A wonderful example of Metamorphosis.The nymph lives under water for 4 years (Some. The transition from water to air is known to be associated with changes in both respiratory chemosensitivity and ventilatory control in vertebrates and crustaceans, but the changes experienced by amphibiotic insects have been poorly explored. Both the nymph and the adult use rhythmic abdominal pumping movements to ventilate their gas exchange systems: the nymph tidally ventilates its rectal gill with water, while the imago pumps air into its tracheal system through its abdominal spiracles. Dragonflies are amphibiotic, spending most of their lives as aquatic nymphs before metamorphosing into terrestrial, winged imagoes.
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