A. Tortoises, turtles and terrapins are reptiles belonging to the biological order
called Testudines. For the most part, there is little difference in a taxonomic or
biological respect (though tortoises do have their own family - a lower classification
- called Testudinidae). So are there any real differences between these three Testudines?
In the main, different names are applied depending on where you live in the world.
For example, in the USA, Testudines that live in the ocean are called turtles or
seas turtles – as they are in say the UK and Australia – but those living on land
are referred to as turtles or box turtles in the States, yet we know them as tortoises
in the UK. To help avoid confusion, many scientists and vets refer to them all as
Chelonians, which comes from the name of their super-order classification (a taxonomic
rank above order) Chelonia, meaning turtle in Greek.
But generally speaking, here are some accepted descriptions of what differentiates
tortoises, turtles and terrapins:
Tortoise (or box turtle) – live on the land, do not have webbed feet, only enter
water to drink and bathe, primarily herbivores, rarely migrate.
Turtle and sea turtle – live mainly in water, some webbed feet to aid swimming, omnivores
eating plants, fish and insects.
Terrapin – sometimes considered a ‘half-way house’ between a tortoise and a turtle,
spend some time on land but are always close to water, usually distinguished from
a turtle in the UK if they live in/around fresh or brackish (slightly salty) waters
as opposed to the sea.
Source(s): Turtles.net, San Diego Zoo, Wisegeek.com, Newworldencyclopedia.com