The Zoological society of London are so excited about all the new species in the Thames that they're asking people to let them know if they spot something. It's so they can try and work out what the marine life is up to.
Porpoises, seals, dolphins and even sea horses have been spotted in the river!
I live up-stream of central London and I'm always out on the river, but I've never seen anything unusual.
The life boat crews who patrol the Thames have seen loads of creatures and they agreed to take me with them on one of their trips.
It was really fun - we didn't see any dolphins or seals - but we did see lots of logs!
Thankfully, I didn't see any evidence of fish that had died from the sewage polution.
I was on the boat in Teddington for about an hour.
I'm often on the river so I'll keep looking for interesting animals.
Sally, 11, London
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