Post-maternal social organisation of Amaurobius ferox (Araneae, Amaurobiidae) provides an opportunity to investigate the mechanisms of social behaviour in spiderlings while controlling for potential effects of maternal presence. Development and characteristics of locomotory behaviours in young individuals of the subsocial Amaurobius ferox were examined. Young collectively show a very rapid and linear locomotion in a short distance in response to an intruder in the natal nest. Such a locomotory behaviour of the spiderlings resembles the successive synchronised stepping towards prey of the permanently social spider, Anelosimus eximius. We observed the development of different types of locomotion relative to the age of young, collective tendency (i.e., proportion of individuals within the clutch engaging in the behaviour), and directional properties of the locomotion. Locomotory behaviours of spiderlings fell into two categories: ‘abrupt locomotion’ (AL), involving fast and linear movement over a short distance; and ‘ordinary locomotion’ (OL), involving slower movement over longer distances and times. The frequency of AL (abrupt locomotion) did not vary much throughout the days post-matriphagy, occurring for a limited period of time. On the other hand, the frequency of OL (ordinary locomotion) varied over the days post-matriphagy and increased during the maternal social period.

• Kil Won Kim(Division of Life Sciences, Incheon National University)
• Soon Kil Ahn(Division of Life Sciences, Incheon National University)
• Kyoung Hye Kim(Division of Life Sciences, Incheon National University)