Definition: Haldane is a name for a rare type of fish, Haldane's (Caretta caretta). It's native to Australia and New Zealand, where it can grow up to 3 meters (10 feet) in length, with some species reaching up to 5 meters (16.4 feet). Haldanes are known for their unique appearance, which includes a silver-like shine that resembles the glow of the sun on water.