Overview
This lecture compares the common snapping turtle and the alligator snapping turtle, highlighting differences in appearance, behavior, and habitat.
Types of Snapping Turtles
- Two main types: the common snapping turtle and the alligator snapping turtle.
- Common snapping turtle averages 30 pounds; native to most of the eastern U.S., parts of Mexico, and Central America.
- Alligator snapping turtle averages 70 pounds; endangered and found in the southeastern U.S.
Behavior and Temperament
- Common snapping turtles are more aggressive and quick to bite than alligator snapping turtles.
- Alligator snapping turtles are calmer, especially when out of water.
- Both species cannot tuck limbs into their shells due to small plastrons.
Hunting and Feeding
- Alligator snapping turtles are ambush predators, using a worm-like appendage in their mouth to lure prey.
- Common snapping turtles are nomadic, actively searching for and hunting prey.
Physical Differences
- Alligator snapping turtles have spiky, rough carapaces (upper shell); common snapping turtles have smoother carapaces.
- Common snapping turtles have large, prominent osteoderms (bony scales) on tails; these become more obvious as they grow.
- Alligator snapping turtles’ osteoderms shrink as tails grow.
- Common snapping turtles have short, blunt noses; alligator snapping turtles have longer noses for easier breathing while submerged.
Habitat
- Common snapping turtles are usually found in ponds and still waters.
- Alligator snapping turtles inhabit slow-flowing rivers and streams.
Evolution and History
- Snapping turtles have existed since the late Cretaceous period, nearly 70 million years ago.
Key Terms & Definitions
- Plastron — the underside shell of a turtle.
- Carapace — the upper shell of a turtle.
- Osteoderm — bony deposits forming scales or plates in the skin.
- Ambush predator — a predator that waits and attacks prey by surprise.
- Nomadic predator — a predator that moves through its environment actively hunting prey.
Action Items / Next Steps
- Review characteristics and distinctions between the two turtle species for identification.
- Prepare for next class/topic: study more about wetland ecosystems and turtle adaptation.