By Stacey Venzel
For hundreds of years, turtles have played an important role in human culture. Our ancestors relied on turtles for food, medicine and spirituality. Today, turtles are protected in many regions because they were hunted near to extinction.
Protecting turtles, whether through the creation of official government-managed sanctuaries or just helping a slow-moving turtle cross a busy street, is important to both humans and the environment. Turtles, tortoises and terrapins may be some of the hardest-working species in the animal kingdom. In addition to being a source of nourishment, medicine and religious worship, the busy members of the order Testudines are also cleaners, protectors, distributors, construction workers and vital indicators of environmental concerns.
Like vultures and raccoons, turtles are the garbage men of the animal world. As scavengers, they help clean up road kill, an important job in the food web that helps the cycle of life continue and reduces the threat of disease. They are not just scavengers, though. Turtles are both predators and prey.
Some turtles, like the North American map turtle, keep our environment in check with their specialized diet. This species feeds mostly on mussels. Overgrowth of mussels can cause blockages in pipelines and weigh down boats when too many attach to the bottom of ships.
With certain diets, turtles also safeguard humans and the environment from pests. Without the leatherback sea turtle, whose diet consists almost entirely of jellyfish, we might not enjoy wading in the waves. Instead, we would spend our time trying to avoid getting stung by jellyfish! Additionally, aquatic turtles that feed on floating food ingest mosquito larvae. A decline in turtle numbers would mean an increase in mosquitoes most likely.
Numerous turtle species also ingest seeds, which are difficult to break down inside the body. Diamondback terrapins have recently been found to transport sea grass hundreds of miles, “planting” the seeds when they poop. Snapping turtles and other freshwater testudines can carry mini gardens on their backs, dispersing seeds as they travel in water or on land.
In addition to being street cleaners and gardeners, turtles wear construction hats, too, building homes for other animals. Tortoises dig burrows, but when they leave one burrow to create another, a new creature can move into their old home. Rabbits, snakes, frogs, mice, owls and opossums are just a few of the animals that might take over the house when the tortoise leaves. The shell of a sea turtle is also a home—and a free ride—for attaching barnacles and remora fish.
Turtles help us learn about our surroundings, too, as indicator species. Research has shown that when the health or behavior of a turtle population changes, it can be linked to environmental issues. For example, turtle illnesses have been traced back to fertilizer run-off contaminating streams, lakes and bays. When we see an increase in the number of sick turtles, we might want to check out the water quality of their habitat. If their aquatic home has high levels of pesticides, then the soil where crops are grown for human consumption might also be reaching toxic levels. If we pay attention to a turtle’s health, it will teach us a few things about our own health.
These ancient animals also play a pivotal role in their environment by acting as foundational building blocks within their ecosystem. Numerous sea turtle species are excellent examples of how removing one population of organisms would cause the collapse of the entire community. Hawksbill sea turtles maintain a balanced ecosystem because they are selective feeders on sponges which then allows less common species of sponges to populate. On land, gopher tortoises act as a keystone species because without their burrows, many organisms would be homeless.
Lastly, these reptiles are often associated with certain endearing human qualities. As biologists Whit Gibbons and Judy Greene commented, “Although some people may perceive minimal value in turtles, others admire their symbolic traits, such as persistence, patience and resilience.”
Elizabeth Armentrout, Laurie Macdonald, “The gopher tortoise: Celebrating a keystone species,” Defenders of Wildlife, May 21, 2015, http://www.defendersblog.org/2015/05/the-gopher-tortoise-celebrating-a-keystone-species/.
Stephen Divers, Doug Mader, Current Therapy in Reptile Medicine & Surgery, (St. Louis, Elsevier Saunders, 2014), 300.
Karen Eckert, David Gulko, Sea Turtles: An Ecological Guide (Honolulu, Mutual Publishing, 2004), 2-3, 43, 52.
Carl J Franklin, Turtles: An Extraordinary Natural History 245 Million Years in the Making (St. Paul, Voyageur Press, 2007), 28, 30.
Whit Gibbons, Judy Greene, Turtle: The Animal Answer Guide (Baltimore, The John Hopkins University Press, 2009), 6, 54.
Robert J Orth, Sarah E Sumoski, “Biotic dispersal in eelgrass Zostera marina,” Marine Ecology Progress Series, December 19, 2012, http://www.int-res.com/articles/feature/m471p001.pdf.
Stacey Venzel, “What is the world’s largest turtle?” The Super Fins, September 30, 2015, https://www.thesuperfins.com/what-is-the-worlds-largest-turtle/.