Question

What is the coiled thread with a barb at the end called?

Answer 1

Nematocysts:

1. Phylum Cnidaria has specific kind of cells called cnidocytes or stinging cells.
2. These cnidocytes have a stinging organelle called nematocyst, containing a barb at the base of the long coiled thread.
3. The outer wall of the cnidocyst is covered by small hair-like projections called cnidocil.
4. When the cnidocils are touched, the thread comes out with rapid acceleration releasing paralyzing toxins.