Lesser Egyptian jerboa
Jaculus jaculus
— Where the name comes from
Iaculus in Latin is the javelin, from iacere, to hurl: iaculum was also the name of a legendary snake that launched itself from trees like a dart. Applied to this rodent it describes the way it moves — it does not run, it projects itself. The common name, jerboa, comes from the Arabic yarbū‘, the same word behind gerbil.
— Facts
- Group
- Mammals · Mammalia
- Order
- Rodents
- Habitat
- Sandy and stony deserts, arid plains
- Range
- North Africa and Arabia, from Morocco to Iran
- Size
- 9–12 cm of body, tail 15–25 cm, 45–75 g
- Diet
- Seeds, roots, leaves, insects
- Lifespan
- 6 years in captivity
— Characteristics
- 01
It moves only on two legs, in bounds of over a metre and a half.
- 02
The tail ends in a black and white tuft and serves as balance and as a prop.
- 03
It never drinks: all its water comes from food and from metabolism.
— What sets it apart
Its hind legs have three toes and the foot bones fused into a single long bone, the cannon — the same anatomical solution as horses and antelope, arrived at by a wholly independent route. It is one of the clearest examples of convergent evolution between a seventy-gram rodent and a half-tonne ungulate: when the problem is running fast over open ground, physics always suggests the same answer.
