7. I will use spine IK for its tail. This tool is great for joints like  tails, antennae, snake etc.

Go to Skeleton -> IK Spine Handle Tool's option, number of span set to 1. This will create 4 CVs for the curve. Too many CVs will make animation tedious.

After spine IK was made, Maya will create a curve that allow you to control the motion of the tail.

In Pick Mask's select by object type, toggle on Select by Type: Curve to select the curve, then right click and hold, select CV from the hot box.

Then, switch your Pick Mask to Select by Component Type: Points. Select the curve's CVs

I will only select from 2^nd CV onward because 1^st CV is the root. Later on, I will parent them to locators to make this CVs easy to select.

7. Select 2^nd CV and go to deform -> create clusters option, select relative then create. You will find out CV has a C beside. Do the same to 3^rd and 4^th CV.

In Hypergraph, you may notice cluster nodes have been created.

Then I will display clusters selection handle to make.

8. Select clusters then -> Display -> object components -> selection handles.

Toggle Pick Mask to Select by Component type: Handles, the select the clusters in window. You may notice + (selection handle) have turned to yellow. Move them away from joints (visible location)

Now switch to Select by Object type: handles, and select the clusters handles, try to move them.

This setup will save us some time when we want animate it in future.

Select the Pelvis joint and move it forward, Cluster handles are not following. To modify it, groups the cluster handles together and select the group, parent it to pelvis. Now select the Pelvis joint and move it again. Cluster handles are following.

O.K, we have finished spine IK setup for tail. It's up to you whether you want to use IK or FK for its arms.