Fish and dragonfly nymph predators induce opposite shifts in color and morphology of tadpoles

Aquatic predatory insects, like the nymphs of a dragonfly, use rapid movements to catch their prey and it presents challenges in terms of movements due to drag forces. Dragonfly nymphs are known to be voracious predators with structures and movements that are yet to be fully understood. Thus, we examine two main mouthparts of the dragonfly nymph (Libellulidae: Insecta: Odonata) that are used in prey capturing and cutting the prey. To observe and analyze the preying mechanism under water, we used high-speed photography and, electron microscopy. The morphological details suggest that the prey-capturing labium is a complex grasping mechanism with additional sensory organs that serve some functionality. The time taken for the protraction and retraction of labium during prey capture was estimated to be 187 ± 54 ms, suggesting that these nymphs have a rapid prey mechanism. The Young’s modulus and hardness of the mandibles were estimated to be 9.1 ± 1.9 GPa and 0.85 ± 0.13 GPa, respectively. Such mechanical properties of the mandibles make them hard tools that can cut into the exoskeleton of the prey and also resistant to wear. Thus, studying such mechanisms with their sensory capabilities provides a unique opportunity to design and develop bioinspired underwater deployable mechanisms.

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Satiation time and predatory behaviour of the dragonfly nymph Mesogomphus lineatus

Hydrobiologia ◽

10.1007/bf00016841 ◽

1976 ◽

Vol 50 (1) ◽

pp. 55-64 ◽

Cited By ~ 19

Author(s):

S. Mathavan

Keyword(s):

Predatory Behaviour ◽

Dragonfly Nymph ◽

Satiation Time

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Unit Activity in the Abdominal Nerve Cord of a Dragonfly NYMPH

Journal of Experimental Biology ◽

10.1242/jeb.39.1.31 ◽

1962 ◽

Vol 39 (1) ◽

pp. 31-44

Author(s):

ANN FIELDEN ◽

G. M. HUGHES

Keyword(s):

Action Potentials ◽

The Body ◽

Peripheral Stimulus ◽

Inhibitory Effects ◽

Nerve Fibres ◽

Dragonfly Nymph ◽

Peripheral Area ◽

Segmental Ganglion ◽

Peripheral Areas ◽

Stimulation Of

1. Electrical activity of single units has been studied in small bundles of nerve fibres split off from the connectives between abdominal ganglia of the dragonfly nymph. Many units showed a resting discharge but activity of other units was only found when the insect was stimulated mechanically. 2. In some fibres the resting discharge was unaffected by mechanical stimulation and such spontaneous activity showed different patterns. These units were identified as interneurones and a prominent feature of their discharge was an irregular firing over long periods and the formation of characteristic intermittent bursts. 3. Responses to tactile or proprioceptive stimulation were investigated in primary sensory fibres and interneurones. The latter showed excitatory and inhibitory effects which were often related to the site of the peripheral stimulus. 4. Primary sensory fibres generally gave action potentials of smaller amplitude and were excited by stimulation of more localized areas. Many fibres traverse at least one connective after they enter a segmental ganglion and most ascend or descend ipsilaterally, but some crossing-over of sensory fibres occurs in the ganglia. 5. Interneurones were classified according to the nature of the peripheral areas from which they received their input. Ipsilateral, contralateral, and bilateral fibres have all been found but so far there is no evidence for any asymmetric fibres. Fibres responding to stimulation of a single segment or of many segments were found. Some of the latter extended over the whole length of the body and it is clear that spikes may be initiated in many of the ganglia through which an interneurone passes. 6. It is evident from this work that a given peripheral area is represented centrally by many interneurones and a great deal of convergence from different areas may occur on individual interneurones.

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The Activity of Single Motor Fibres in Arthropods I. The Dragonfly Nymph

Journal of Experimental Biology ◽

10.1242/jeb.42.3.447 ◽

1965 ◽

Vol 42 (3) ◽

pp. 447-461

Author(s):

ANN KNIGHTS

Keyword(s):

Electrical Stimulation ◽

Temporal Summation ◽

Reciprocal Relationship ◽

Response Patterns ◽

Insect Muscle ◽

Frequency Sensitivity ◽

Single Motor ◽

Dragonfly Nymph ◽

Central Inhibition ◽

Stimulation Of

1. Responses to mechanical and electrical stimulation have been investigated in single motor fibres dissected in the segmental nerves of the dragonfly nymph. 2. A large proportion of fibres possessed a background discharge which was often accelerated of inhibited on stimulation. Examples of central inhibition were common. 3. Efferent responses varied in type, delay and regularity, both with the input under stimulation and with the frequency and intensity of the volley. The majority of fibres responded to stimulation of more than one nerve root. 4. In many motor fibres changes in the parameters of stimulation demonstrated a reciprocal relationship between and frequency. An enhanced responsiveness occurred with frequency increases in the range of 10-100/sec. indicatind a considerable importance of temporal summation/facilitation. 5. The characteristic frequency-sensitivity of motor fibres and the variability of their response patterns are discussed in relation to the control of insect muscle.

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