Antivirus On Samrt Phone?

Hi all,

I have just purchased the Samsung Galaxy S5 and love it. My problem is Do I need an antivirus or Malware protection for it? I only use the internet at Wi-Fi spots, and NEVER for banking - just checking emails, Facebook, EBay and a general Google search. Obviously I will have to login to some of those, therefore do I need an antivirus of some sort.?

Any help on the best free preferably, will be appreciated. I already have Bitdefender on my laptop and desktop.