Aldabra giant tortoise
Large tortoises are among the longest-lived animals. Some individual Aldabra giant tortoises are thought to be over 200 years of age, but this is difficult to verify because they tend to outlive their human observers. Adwaita was reputedly one of four brought by British seamen from the Seychelles Islands as gifts to Robert Clive of the British East India Company in the 18th century, and came to Calcutta Zoo in 1875. At his death in March 2006 at the Kolkata (formerly Calcutta) Zoo in India, Adwaita is reputed to have reached the longest ever measured lifespan of 255 years (birth year 1750). Today, Jonathan, a Seychelles giant tortoise ("A. g. hololissa"), is thought to be the oldest living giant tortoise at the age of years and Esmeralda is second at the age of years, since the death of Harriet at 176, a Galapagos giant tortoise. Esmeralda is an Aldabra giant tortoise.
Galápagos green turtle
The unique morphological distinctions of the Galápagos green turtle have given rise to the debate. The two most notable distinctions are the considerably smaller adult size and the much darker pigmentation of the carapace, plastron, and extremities. Other distinctions are the curving of the carapace above each hind flipper, the more dome-shaped carapace, and the very long tail of adult males. The main argument that separates "agassizii" from other "Chelonia" populations is that with a smaller adult size, mating with a female black sea turtle would be very difficult for a male of another subpopulation. A male sea turtle must have a fairly strong hold of the female's carapace during mating to successfully copulate; with the female "agassizii" being much smaller, this feat would be impossible. This, in turn, creates an isolation of "agassizii" from the genetic variations shared by other populations of green sea turtles in the Pacific.