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Thursday, Feb. 12, 2004
By ROWAN HOOPER
* Japanese name: Ogasawara yamori
Description: Also known as the dark-house gecko, the mourning gecko is smooth-skinned and about 45 mm long, not including the tail, which can add another 45 mm. You will probably hear it before you see it: It makes a distinctive chik chik chik noise that sounds rather like a suppressed sneeze. The geckos vary in color, between creamy brown and gray, but the underside is always beige. Mourning geckos are reported to change color according to temperature. At around 30 degrees they are light brown with dark spots from the neck to the tail-base, at around 20 degrees they get darker with dark bands.
Where to find them: The Ogasawara Islands (also known as the Bonin Islands) and Okinawa. The mourning gecko is nocturnal, which might explain its melancholy name (but see below). They have been found in mangrove trees, on coastal rocks, in palm trees and under loose tree bark. They also live in human habitations, but they don't do so well in city areas.
Food: Mostly nocturnal insects, such as crickets, flies and moths. When approaching their prey, geckos apparently sway their tail like cats, perhaps for the same reason (to distract the prey from the mouth, the danger area).
Special features: Mourning geckos reproduce by parthenogenesis ("virgin birth"), which means that females don't need males. (Is that why they are in mourning?) Eggs develop into embryos without requiring sperm. Consequently populations are entirely female and within a population there is very little genetic variation. Between populations, however, there can be big differences. For example, some clonal lineages are diploid (like humans) and have two copies of each of their 22 chromosomes (making a total of 44), but some are triploid, with three copies and have 66 chromosomes. Some excitable researchers have reported "homosexual" behavior: Females have been seen holding others down for several minutes with a bite on the neck or tail. This behavior is probably a means of establishing hierarchy in a group.