Temptress and siren, when exposed, wound up bloody parasites (7,4)

I believe the answer is:

vampire bats

I'm a little stuck... Click here to teach me more about this clue!

'bloody parasites' is the definition.
The definition and answer can be both animals as well as being plural nouns.
Maybe they are linked in a way I don't understand?

'temptress and siren when exposed wound up' is the wordplay.
'temptress' becomes 'vamp' (I've seen this in another clue).
'and' means one lot of letters go next to another.
'when exposed' says to take the centre (the inside letters become exposed).
'wound up' becomes 'bats' (I can't explain this - if you can you should give a lot more credence to this answer).
The central letters of 'siren' are 'ire'.
'vamp'+'ire'+'bats'='VAMPIRE BATS'

Can you help me to learn more?

(Other definitions for vampire bats that I've seen before include "animals" , "Start" .)

I've seen this clue in The Telegraph.

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