In Exodus 4:4, when Moses seizes the rod-turned-serpent by its tail, this signifies that law of God can raise up the lowest, most sensory parts of our nature. (Arcana Coelestia 6952)

Tail here also signifies persuasive sensuous knowledges. (Apocalypse Explained 559, Doctrine Regarding Sacred Scripture 13)

'Tail' signifies the opposite extreme of the head, because the brain is continued to the tail through the spine, This is why the head and tail make one, as the first and last. Where 'head' signifies faith alone justifying and saving, 'tail' signifies everything that confirms that belief, taken from the Word, and so the truths of the Word are falsified.... Because a 'tail' signifies the extreme, and so it is the sum or aggregate, Jehovah told Moses to 'take the serpent by the tail, and he took it, and it became a rod,' in Exodus 4:3-4. This is also why they were commanded to 'take off the whole tail near the backbone, and sacrifice it together with the fat of the entrails, kidneys, intestines, and liver,' as in Leviticus 3:9-11, 8:25, 9:16, and Exodus 29:22. 'Tails' signify sensory knowledge, because the tails of animals are continuations of the spine, or spinal cord, which contains the base of the cerebrum, which signifies intelligence and wisdom. The low extremes of intelligence and wisdom are sensory knowledge.

(Referencat: Apocalypse Revealed 438; Exodus 3, 4:3; Revelation 9)