Use an Array Modifier with an "object offset" (using an empty) to create a tapering effect where the tail gets thinner toward the end.
The movement of tentacles is typically achieved through specialized rigging rather than standard limb armatures. 3D Workflow (Blender) PB HD - Tentacles for anime girl.mp4
To achieve a professional "anime" look, apply these stylistic principles: How I Animate a Scene from Beginning to End Use an Array Modifier with an "object offset"
Draw a rough sketch or use a 3D room model as a reference to establish perspective, as characters moving toward the camera must grow exponentially larger. 2. Modeling and Rigging Tentacles PB HD - Tentacles for anime girl.mp4