Fig. 6. Block climbing in aged and young cockroaches. (A) Posture of aged animal when approaching a three-block obstacle. (B) After detecting the obstacle, animals often change their body posture by rotating the mesothoracic legs forward and `rearing up' the front of the body. (C) Some aged individuals do not alter their body angle and run into the side of the block ('head butt'). (D) Summary of climbing behaviors in aged and young cockroaches. In most of the trials, aged animals rear up before reaching the block (as seen in young animals). However, in a few trials, aged cockroaches with `tarsus catch' run into the side of the block before climbing over it.