Table 1.

Orientation behavior of tadpoles (stages 47–56) in five different experimental groups

Group	Orienting (%)	Mean orientation angle (range)	Median interval to orient	n
No current	14	85 (0–180)	–	28
Untreated	100	3 (0–36)	1	28
Cobalt	62	33 (0–180)	2	36
Streptomycin	45	37 (0–180)	3	21
Gentamicin	76	14 (0–90)	1	25

Each animal was tested only once. The untreated, cobalt-treated, streptomycin-treated and gentamicin-treated animals were all tested under current conditions. Tadpoles tested under no current conditions received no drug treatments. The percentage of animals in each group orienting within 45° of the current source is shown as % orienting. Mean orientation angle for each animal was calculated from 10 s intervals for a total of 3–5 min and then averaged across the entire group of animals in a particular group. Orientation angle and its range are in degrees. Orientation angle varied significantly between the five groups (see text). For each animal, the first observation interval (30-s bins) at which orientation remained at 0° for at least four intervals was calculated, and then used to calculate median interval to orient for that group. n number of tadpoles per group