The HealF tag of a Spider decreases with it's Health.
Steps to reproduce:
1.Spawn a Spider (In my case I was using a Spawn Egg and the Spider and I were the only two entities in a Superflat world)
2.Use the command "/entitydata @e {}" to display the Spiders NBT tags in the chat and then compare the "Health" (actual Health the mob is at) and "HealF" tag (maximum Health of the mob, should not change)
3.Punch the Spider (without a weapon)
4.Repeat from Step 2.
To see how it should work try the same experiment with a zombie.
EDIT: Well it indeed happens to the zombie too, but only when it deals damage from burning in sunlight (not burning in general)
Same as Spiders for Creepers... (Did not continue testing then because the problem is all the same)
~tobsam
Linked issues
Comments 3
I just noticed I made a major mistake here, HealF is not the maximum health of the mob, it is a more acurate Health tag, since it is a float variable...
You can close the report...
(I am still experimenting with the zombie punching, since it appears to deal 0.98 half hearts of damage to punch him, but I will open a new report after some testing...)
Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases. If this has been done, we can reopen the issue.
Keep in mind that the "Resolved"-Status on this ticket just means "Answered", and that we are waiting for further information on whether this issue still exists or not. We will reopen it as soon as the requested information has been delivered.