When hamsters are young, they all look pretty much alike and can be hard to tell apart. As they age, it becomes easier to identify sexual characteristics. By the time a hamster is sexually mature, which can be as young as 10 weeks old for males and 6 weeks for females, it’s usually easy to tell them apart. One clear indication is the obvious presence of testicles in the males.
The age of the hamster will affect whether or not his testicles are visible. In young hamsters, particularly those under 4 weeks old, the testicles are not always noticeable. Even when these organs have begun to develop, males can retract them for a period of time, making the testicles more difficult to spot. As the hamster ages, the testicles get larger and are typically easy to see on the underside of the hamster, near the tail.
The testicles on a mature male hamster are usually quite obvious and appear as two relatively large growths near the rear of the animal. These may be very large, and some owners have even mistaken them for tumors or other undesirable growths. Adult males often have little or no hair in the genital area, making the testicles easier to see. When viewed from above, the rear end of a male hamster typically appears to protrude, making the area around the tail look triangular. Females, on the other hand, look compact, round and smooth.
Testicles make the sperm necessary for reproduction; without testicles a male hamster could never father babies. When the hamster mates, the testicles send sperm-filled fluid out of the male’s body and into the female, where the sperm can fertilize her eggs. If all goes well, as it usually does with hamsters, the female will produce a litter of young after about 16 days. If the testicles remain inside the male’s body, he will most likely be infertile, since his body temperature will kill off the sperm.
The male hamster’s testicles are not readily visible in all types of hamsters. Some breeds don’t have very large, obvious testicles. The long, hairy coats of some hamsters may make their testicles harder to find, though they should show up in a careful inspection of the hamster’s underside. When the testicles are not visible, the distance between the two openings on the underside of the hamster will provide a clue as to whether it is male or female. In males there is an obvious space between the anus and the location of the penis.
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