The Syrian Hamster, is a very well-known member of the rodent subfamily, Cricetinae. They are popular as housepets and scientific research animals. Adults grow from 5 to 7 inches (13 to 18 cm) in length, and will usually have a lifespan of 2 to 3 years. They do not like direct sunlight. Although often considered nocturnal, Syrian hamsters are most active at dusk and dawn.
Hamsters have expandable cheek pouches, which extend from its cheeks to its shoulders. In the wild, hamsters are larder hoarders; they use their cheek pouches to transport food to their burrows.
Sexually mature female hamsters come into season every four days. Syrian hamsters have the shortest gestation period in any known placental mammal at only 16 to 18 days. They can produce large litters of 20 or more young, although the average litter size is between 8 to 10 pups. If a mother hamster is inexperienced or feels threatened, she may abandon or even cannibalize her pups. A female hamster will come into season almost immediately after giving birth, and can become pregnant despite already having a litter. This puts a lot of stress on the mother's body and often results in very weak and undernourished young.
Hamsters are extremely territorial and may attack other individuals. Even brothers and sisters, once mature, may attack one another. In captivity, babies should be separated from their mother and by gender after 4 weeks as they can often breed from 4–5 weeks old so care should be taken to prevent such close inbreeding, and the same-sex groups of babies can be housed together only for a further 3 weeks until they feel the need to establish territories.
Syrian hamsters mark their burrow with secretions from special scent glands located on their hips. Male hamsters in particular lick their body near the glands, creating damp spots on the fur. They then will drag their sides along objects to mark their territory, whereas females will often use bodily secretions and feces.