Heartbroken Phoebe Downs, 20, has owned Marigold and Clover since she was ten and says the pair have helped her cope with an anxiety disorder.
She said: “Looking after them and my other animals gave me something positive in my life and provided a constant focus for me.
“I even wrote my recent college project dissertation on the importance of animals for humans psychological health. I’m absolutely heartbroken that this has now happened.”
Ms Downs added: “Even though I was young when I got them, I knew what I was undertaking and had planned to have them my whole life - I’d planned to grow old with them and have had this chance robbed from me.
“We’re desperate for anyone to come forward. We’re not interested in anything other than getting them back home. No questions asked - just want them put back where they were found. If anyone knows of someone who has recently acquired some adult tortoises or has been offered them we want them to get in touch.”
The tortoises are reported to have gone missing during the day or night of July 1 from Roundle Square Road, Felpham, Bognor Regis.
Described as ‘about 20cm in size’, one is slightly larger and lighter ‘with a distinctive scar on her shell’.
Anyone with information is asked to call Phoebe Downs on 07931771907.