| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2005: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2004: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
Self-recognition is assumed to be limited to some higher vertebrates such as humans, chimpanzee, orangutan and dolphins. Cephalopod mollusks, particularly the octopus, also exhibit intelligent behavior and the related squid may have similar abilities as they form highly organized schools in which they show complicated communication, reflecting advanced sociality and awareness. Here we show that the oval squid (Sepioteuthis lessoniana) possess self-awareness using a mirror self-recognition (MSR) test. The squid expressed great interest in its own mirror image which was not observed against control non-reflecting objects. This suggests self-recognition exists in this invertebrate sub-phylum and considerably extends our own awareness of consciousness in the animal kingdom. MSR of adult Sepioteuthis lessoniana was appeared as mirror-touching behaviour, in which squid touches mirror surface by its arm tip repeatedly. Contrary, squid that was isolated for a long duration in a separate tank lost the mirror-touching behaviour. He did not touch the mirror, but he froze in front of the mirror as if he was nervous or attached himself to the mirror surface. These abnormal behaviours suggest that social condition (i.e., existence of conspecific individuals) strongly affects the supposed MSR in Sepioteuthis lessoniana, a social species. As for the problem on MSR is genetically determined behaviour or not, mirror-touching behavior has been already observed in hatchling of Sepioteuthis lessoniana. However, its frequency was relatively low compared with mirror-touching behaviour of adult squid. Mirror-touching behaviour became active as in adult after 50 days of hatching, which suggests the similarity of ontogeny of MSR in human and primates.
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