query: How many species of turtle are there?
passage: Turtle
Turtles are diapsids of the order Testudines (or Chelonii[3]) characterized by a special bony or cartilaginous shell developed from their ribs and acting as a shield.[4] "Turtle" may refer to the order as a whole (American English) or to fresh-water and sea-dwelling testudines (British English).[5] The order Testudines includes both extant (living) and extinct species. The earliest known members of this group date from million years ago,[1][6] making turtles one of the oldest reptile groups and a more ancient group than snakes or crocodilians. Of the 356 known species[2] alive today, some are highly endangered.[2]
passage: Canadian Organization for Tropical Education and Research
The marine turtle monitoring, being the largest project at the station, looks to conserve and protect existing sea turtle species.The program began in 2004, with tagging of the species beginning in 2006. The project also works with the Sea Turtle Conservancy and Ministry of Environment, Energy and Sea (MINAEM) of Costa Rica to gain a wider understanding of the species'. Playa Norte, the beach that the station is located near, is home to four of the existing seven sea turtle species. This includes, green, leatherback, hawksbill and loggerhead sea turtles. During nesting season, (March until November) volunteers and interns survey the beach to insure safe nesting and hatching of the sea turtles.