The primary animal that only has 2 legs, based on the provided reference, is a human.
While the question directly asks for "animal," it's important to understand that within the context of the provided reference, multiple animals use bipedalism (walking on two legs) at various times. However, the defining characteristic for the prompt's answer is that humans are fundamentally obligate bipeds; walking on two legs is their standard mode of locomotion, as the reference states "humans walk bipedally".
Bipedalism in Animals:
It’s also worthwhile to explore which animals utilize bipedal movement, even if it’s not their primary method of locomotion.
| Animal Type | Bipedal Behavior | Reference Information |
|---|---|---|
| Humans | Walk bipedally | Standard mode of locomotion |
| Birds | Walk, run, hop bipedally | Many birds use bipdeal motion |
| Apes | Walk bipedally (occasionally) | Not the primary method of locomotion |
| Lizards | Run bipedally | Some lizards can run bipedally |
| Cockroaches | Run bipedally (at high speeds) | At their highest speeds |
| Kangaroos | Hop bipedally | Kangaroos use bipedal hops |
| Some Rodents | Hop bipedally | Some rodents use bipedal hops |
| Jerboas | Skipping gait | Jerboas use a skipping gait |
| Crows | Skipping gait | Crows use a skipping gait |
Key Points:
- Humans are fundamentally bipedal.
- Many other animals use bipedalism but often as a secondary mode of locomotion.
- The reference specifically focuses on walking and running bipeds.
Conclusion
Humans are obligate bipeds, while other animals use bipedalism as a secondary movement form. Therefore, the answer to the question is humans.
