Blastoise #009

Aldabra giant tortoise

Childzy (CC BY-SA 3.0)

There are only two living species of giant tortoises–the Aldabra giant tortoise (found in the Aldabra Atoll) and the Galápagos giant tortoise (found in the Galápagos Islands). Giant tortoises can reach a weight of over 900lb and a length of over 4ft.

Each species of giant tortoise originally came from an inland population, which dispersed across the ocean and then evolved over time to form a separate species. The ancestors of the Aldabra giant tortoise came from Madagascar, and the ancestors of the Galápagos giant tortoise came from South America. As a result, giant tortoises are more closely related to their respective source population than they are to each other (Le M et al. 2006).

The Aldabra Islands form the largest lagoon in the Indian Ocean

Simisa (CC BY-SA 3.0)

A lagoon is shallow water encircled by a barrier, such as a ring of coral reefs. An atoll is a type of lagoon that occurs in warm oceans.

A photograph of the Galápagos Islands from the International Space Station

The Galápagos Islands were formed by volcanic activity. There are active volcanoes found among the archipelago. These volcanoes produce magma and leave behind massive craters.

Loggerhead sea turtle

Public Domain

The loggerhead sea turtle (Caretta caretta) can weigh up to 1200 pounds. Its large, powerful jaws are able to crush clam shells and sea urchins. It has the widest geographic distribution of any sea turtle. Yakushima Island in Kagoshima Prefecture, Japan, is an important nesting site for loggerhead sea turtles (Spotila 2004).

Le M, Raxworthy CJ, McCord WP, Mertz L (August 2006). "A molecular phylogeny of tortoises (Testudines: Testudinidae) based on mitochondrial and nuclear genes". Molecular Phylogenetics and Evolution. 40 (2): 517–31.

Spotila, James R. (2004). Sea Turtles: A Complete Guide to their Biology, Behavior, and Conservation. Baltimore, Maryland: The Johns Hopkins University Press and Oakwood Arts.