At some time during your stay at Riviera Maya you will encounter a ctenosaura similis. This less-than-attractive reptile with a row of teeth along its spine can grow up to four feet. Your first reaction is to recoil and maybe scream. But if you want to snap a photo after you recover from your initial shock, you’d better grab your smart phone quickly. The Guinness Book of World Records has clocked this adorable black spiny-tailed iguana at nearly 22 miles per hour.