10 things we didn't know last week

1. Piranhas bark.
More details
2. Brunettes make better friends.
More details (Daily Mail)
3. Self-made millionaires are more likely to have gone to state school.
More details (Daily Telegraph)
4. One in six mobile phones in Britain is contaminated with poo.
More details
5. Penguins rescued from oil slicks get knitted jumpers to keep them warm.
More details

6. There will be more people in the Millennium Stadium in Cardiff on Saturday to watch the Wales v France World Cup semi-final on video screens than there will be at the actual match in New Zealand.
More details (Guardian)
7. Meerkats recognise each others' voices.
More details
8. Lady Gaga doesn't like Lady Goo Goo.
More details (Sun)
9. Babies know if someone is being unfairly treated at just 15 months.
More details (Daily Telegraph)
10. Really good sex can wipe your memory.
More details (Daily Mail)
Seen 10 things? Send us a picture to use next week. Thanks to Jane Lidstone for this week's picture of 10 pedaloes on the River Dee in Chester.