Parasites found in stream POW churned up (9)

I believe the answer is:

tapeworms

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'parasites' is the definition.
The answer and definition can be both animals as well as being plural nouns.
Perhaps there's a link between them I don't understand?

'stream pow churned up' is the wordplay.
'churned up' is an anagram indicator (letters churned or mixed up).
'stream'+'pow'='streampow'
'streampow' anagrammed gives 'TAPEWORMS'.

'found in' is the link.

Can you help me to learn more?

I've seen this clue in The Independent.

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