There are 7 types of sea turtles in the ocean: green, Kemp's ridley, leatherback, loggerhead, hawksbill, flatback, and the olive ridley. 6 of the 7 range from "critically endangered" to "vulnerable" according to the IUCN Red List of Threatened Species. The IUCN lacks a sufficient amount of data to confidently label the status of the flatback (the last of the 7).
Each type of turtle has a unique diet, but many munch on seagrass, jellyfish, shrimp or algae. Floating plastic trash is often mistaken for delectable jellies. After swallowing a plastic bag, a sea turtle risks choking. If it does manage to swallow, it runs the risk of continuously feeling "full" because the plastic doesn't digest. If the turtle never feels hungry, then it won't eat. This can lead to starvation.
Sea turtles dig giant holes to lay their eggs on the beach. The sex of the newborns is determined by temperature. If the nests temperature is below 85°F the hatchlings will be predominately males. If it is above 85°F, you can expect females.
You hear a lot about "saving the sea turtles", but why should we care? As members of both coastal and marine environments, the decline of sea turtles will impact both spheres. Sand dune ecosystems along the coast rely heavily on the nutrients from left over eggshells or unhatched eggs to keep beaches intact. Without these key nutrients, the plants scattered along dunes would die off, leaving the beaches exposed to harsh wind and water elements.
Because of their grazing activities, sea turtles are also considered "keystone species" for many sea grass beds and coral reefs. Much like deer grazing on plants in a forest ecosystem, sea turtles keep algae and grasses in check so they don't overrun the environment. We can also thank them for keeping the stinging jellyfish populations under control.
Without sea turtles, we would not have a lot of the species and coastal elements that many of our cultures and economies heavily rely on. We tip our hats to the sea turtles!