触手

1. Origins, structure, and basic meaning

• Structure: 触手 (しょくしゅ) can mean an animal's tentacle or, figuratively, an expanding reach. Both examples combine it with 伸ばす, but their semantic domains differ.
• Basic usage: An octopus physically extends a tentacle; harmful solicitation figuratively extends its reach as far as students.

2. Common pitfalls and similar expressions

• Literal tentacle and figurative reach
  • タコが触手を伸ばす is a physical movement of an organ. 勧誘は…触手を伸ばす is an idiom for expanding influence and should not receive the biological reading.