Chordates • Earth.com

Desert tortoise

(Gopherus agassizii)

galery

Description

The desert tortoises (Gopherus agassizii and Gopherus morafkai ) are two species of tortoise native to the Mojave and Sonoran Deserts of the southwestern United States and northwestern Mexico and the Sinaloan thornscrub of northwestern Mexico.G.agassizii is distributed in western Arizona,southeastern California,southern Nevada,and southwestern Utah.The specific name agassizii is in honor of Swiss-American zoologist Jean Louis Rodolphe Agassiz.Recently,on the basis of DNA,geographic,and behavioral differences between desert tortoises east and west of the Colorado River,it was decided that two species of desert tortoises exist: Agassiz's desert tortoise (Gopherus agassizii ) and Morafka's desert tortoise (Gopherus morafkai).G.morafkai occurs east of the Colorado River in Arizona,as well as in the states of Sonora and Sinaloa,Mexico.This species may be a composite of two species.The new species name is in honor of the late Professor David Joseph Morafka of California State University,Dominguez Hills,in recognition of his many contributions to the study and conservation of Gopherus.The desert tortoises live about 50 to 80 years;they grow slowly and generally have low reproductive rates.They spend most of their time in burrows,rock shelters,and pallets to regulate body temperature and reduce water loss.They are most active after seasonal rains and are inactive during most of the year.This inactivity helps reduce water loss during hot periods,whereas winter hibernation facilitates survival during freezing temperatures and low food availability.Desert tortoises can tolerate water,salt,and energy imbalances on a daily basis,which increases their lifespans.These tortoises may attain a length of 10 to 14 in (25 to 36 cm),with males being slightly larger than females.A male tortoise has a longer gular horn than a female,his plastron (lower shell) is concave compared to a female tortoise.Males have larger tails than females do.Their shells are high-domed,and greenish-tan to dark brown in color.Desert tortoises can grow to 4–6 in (10–15 cm) in height.They can range in weight from.02 to 5 kg (0.044 to 11.023 lb).The front limbs have sharp,claw-like scales and are flattened for digging.Back legs are skinnier and very long.

Taxonomic tree:

Domain:
Kingdom: Animalia
Phylum:
Class: Reptilia
Order:Testudines
Family:Testudinidae
Genus:Gopherus
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