Justin Bieber is scared of spiders.

The 21-year-old pop superstar has confessed he suffers from arachnophobia and can't stand the thought of the eight-legged bugs crawling on him

Revealing 20 things his fans don't know about him for Cosmopolitan.com, he said: ''(I'm secretly terrified of) spiders.''

Justin also admitted to having a useful endurance skill when swimming.

When asked to reveal one thing even 'Beliebers' don't know about him, he said: ''​I can hold my breath underwater for two minutes.''

The 'Boyfriend' hitmaker also lifted the lid on what he likes about girls and how little he understands the opposite sex.

Justin - whose most high-profile relationship has been with Selena Gomez - admitted he hates it when girls wear ''​gladiator sandals'' but loves seeing woman squeeze their curves into ''​booty shorts''.

When asked what one of the things he's learned about women, he frankly answered: ''​They are complicated.''

Although he takes notice of women's fashion choices and how they look the singer insists the thing he finds sexiest about any girl he's romantically keen on is ''her attitude''.