ISSN:
1432-1351
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary 1. The ecdysial growth of cercal filiform hairs was investigated in the cricketGryllus bimaculatus. The length of hairs varied from 40 to 500 μm in the 1st, from 40 to 650 μm in the 3rd and from 30 to 800 μm in the 5th instar nymphs (Fig. 1). Hemimetabolous development causes both hair growth and the appearance of new hairs at each ecdysis (Figs. 2, 3). The newly acquired hairs were shorter than 200 μm in every case (Fig. 4). 2. Velocity thresholds of cercal sensory interneurons (CSIs) to sinusoidal air-currents were measured in 3rd instar nymphs (Fig. 5 A, B, C). CSIs 8-1 (medial giant interneuron: MGI) and 9-1 (lateral giant interneuron: LGI) showed threshold curves of acceleration sensitivity similar to those in adults. The thresholds for CSIs 8-1 and 9-1 were on the average higher in nymphs than in adults. The threshold curves for the two velocity-sensitive CSIs 10-2 and 10-3 were similar for nymphs and adults. 3. Velocity thresholds of cercal filiform sensilla were measured in 3rd instar nymphs (Fig. 6). In spite of the small size of nymphal hairs, the most sensitive ones showed the same sensitivity as did the long 1000 μm hairs of the adult. 4. The filiform hairs in 3rd instar nymphs were supported by a weaker spring than in adults (Fig. 7). Relative stiffness was about 50% of that in the long hairs in adults, but not much different than that in the short hairs. 5. Based on a theoretical estimation of hair motion, the threshold angle of a filiform sensillum in the 3rd instar nymph was calculated (Fig. 9). Threshold angles of the long sensilla seemed to be unchanged throughout hemimetabolous development.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01342632
Permalink
