Hamsters are known for being adorable, running around in their little wheels or balls or munching on something.

They're considered good starter pets for kids when they're not quite ready for a more demanding animal, like a dog. This is especially true since hamsters can easily entertain themselves for hours.

Still, there's more to these little balls of fluff than being the cutest thing you've ever seen, including the fact they seem to be able to hold their alcohol pretty well. Here are an array of surprising facts about them.

1. There are 18 species of hamsters. Belonging to the family Cricetidae, which includes voles and lemmings as well as rats and mice native to the Americas, hamsters are a varied lot. Some are more ratlike, like the seven members of the Cricetulus genus, while the lone member of the Cricetus genus, the European hamster, is pretty darn adorable. The most popular species, since they're often taken in as pets, are the golden or Syrian hamster (Mesocricetus auratus) and three different members of the Phodopus genus, or dwarf hamsters: the winter white dwarf hamster (Phodopus sungorus), Campbell's dwarf hamster (Phodopus campbelli) and the Roborovski hamster (Phodopus roborovskii).

European hamster stands upright in some soil The European hamster is just one of nearly 20 hamster species. (Photo: katanski/Wikimedia Commons)

2. Hamsters are nocturnal creatures. Given their reputation as great pets, it's a little odd that hamsters are most awake during the night. Of course, being awake at night out in the wild makes sense for these tiny animals. They're prey animals, after all, and they hide as much as possible during the day to avoid being eaten by larger carnivores. Outside of the pet hamster world, the animals' coat will have different colored stripes to help them blend in more. Given that they're prey animals, this is also why pet hamsters aren't fans of sudden movements, loud noises and new environments.

3. Hamsters are promiscuous. Male and female hamsters will each have multiple mates. During breeding season, males will head down into any burrow and mate with whatever female they find, provided said female hasn't already mated yet. Once she has mated though, a copulatory plug forms and prevents any further insemination. Females will normally birth around four litters a year — their gestation period is only 15 to 22 days — and litter sizes can range from one to 13 young, though the average is around five to seven.

4. Hamsters are banned in Hawaii and California. Given their high reproductive rate and the fact that both states have climates similar to the hamsters' preferred desert climates, the critters are illegal in Hawaii and California. The hamsters could quickly establish large colonies in the states if they ever escaped into the wild, which would pose a problem for agriculture and other species.

Hamster pokes out from hole in cardboard Chewing on wood or cardboard is better than chewing on the bars of a cage for hamsters. (Photo: Ilyashenko Oleksiy/Shutterstock)

5. Hamster teeth never stop growing. Hamsters can develop overgrown incisors rather quickly since their teeth grow at a steady pace. Overgrown teeth can result in issues with eating, closing their mouths and they can even break off if the top and bottom incisors come into contact. PetMD recommends providing pet hamsters with chewable wood toys so the fuzzy critters have something to gnaw on. Providing plenty of things to chew on and keeping them entertained will stop hamsters from chewing on the bars of their habitats, something you definitely don't want.

6. Hamsters have a high tolerance for alcohol. You'd think that since they don't weigh a great deal, hamsters would be lightweights when it comes to booze, but not so. A 2015 study published in Behavioral Processes found that Campbell's dwarf hamsters can drink about 10 times the amount of ethanol that a human could before exhibiting any signs of drunkenness. The reason could be a particularly active set of alcohol dehydrogenase enzymes.

A hamster stares at a camera from its hamster wheel Hamsters can entertain themselves, provided they have enough toys and places to burrow and hide. (Photo: EniSine/Shutterstock)

7. Hamsters are prone to bacteria and viruses that they can then give to humans. According to the Human Society of the United States, hamsters carry salmonella and, while rare, are also prone to Lymphocytic choriomeningitis, a virus that can result in flu-like symptoms. Children under the age of 5 and pregnant adults are particularly at risk. This transmission of germs goes both ways, however. Hamsters can catch the flu and the common cold from humans, and the symptoms of a hamster cold are the same as they are for humans: a runny nose, fatigue and sneezing. So if you're sick, avoid handling your hamster, and be sure to keep their habitat clean and away from any drafts.

8. Hamsters have moods. Given that we know lots of other animals have moods, this shouldn't be a big surprise. A 2015 study from Royal Society Open Science found that hamsters with extra toys and cozy bedding options will make more optimistic choices. In the study, hamsters learned to avoid water bottles that contained bitter water in favor of sweeter water. Then, researchers either gave the hamsters more toys or they took toys away. Regardless, the hamsters had access to a mystery bottle of water. Those who had plenty of toys were more likely to drink from the bottle while those who had toys and bedding taken away avoided the water. This suggests the hamsters with better habitats were more optimistic about uncertain futures than their deprived cohorts. So, if you have a pet hamster, be sure to provide it plenty of enrichment opportunities to keep it happy.

8 surprising facts about hamsters
Hamsters are popular pets, but these cuddly rodents are also full of surprises.