Of Mouse and Rat

Someone asked me if the rat and mouse are the same, since basically my mother tongue refers these two as 'tikus'.
"Mouse and rat, rat and mouse, they are just the same arent' they?", is what he said after reading my previous post.
but i replied "no".

What do the terms rat and mouse mean?

Rat and mouse are actually not scientific classifications. These words are common names for rodents that look alike to the casual eye.

Rat is used to describe medium-sized rodents with long thin tails. There are many species of rodent that are called rats -- kangaroo rats, cotton rats, Norway rats, black rats,etc, and these different rodent species may not be closely related to each other at all!

Mouse is used to describe tiny, sparrow-sized rodents with long thin tails. As with rats, there are many species of rodents called mice which may or may not be closely related to each other.

So, which rats and mice are you talking about?
Commonly, people are referring to the domestic or pest rats and mice, which means :

• Norway rats (Rattus norvegicus),
  
  
  

• black rats (Rattus rattus),
  
  
  
  
  
  
• house mice (Mus musculus).
  
  
  
  
  
  

Differences between rats and mouse

Theoritically speaking, rats and mice are different in a numbers of terms, such as genetic,anatomy, growth morpholigical,etc.

1. Genetic
   
   • Rats have 22 chromosome pairs, mice have 20 (et Levan 1991).
   • Rats have 2.75 million base pairs while mice have 2.6 million (humans have 2.9).
   • About 90% of rat genes have counterparts in the mouse and human genomes (Rat Genome Sequencing Consortium 2004).
   
   
2. Growth
   • In general, rats develop more slowly than mice.
   • For example, Norway rat gestation is slightly longer (21-24 days) than house mouse gestation (19-20 days).
     
   • Norway rats lactate for about 3 weeks, house mice for 2 weeks.
   • Both species are born naked and blind, but Norway rats open their eyes at 6th days, they are fully furred at 15 days. House mice open their eyes at 3rd days, have fur at 10 days.
     
     
3. Anatomy
   
   • Rats have 6 pairs of nipples, mice have 5 pairs.
     
     
4. Morphological
   
   • Rats are larger, heavier and longer than house mice
   • Norway rat: 350-650 grams, 9-11 inch bodies and 7-9 inch tails
     
   • House mice: 30-90 grams, 3-4 inch bodies and 3-4 inch tails
     
   • The heads of rats are heavy, blunt and chunky, while mouse heads are small and sharply triangular with pointed muzzles.
   
   
5. Others
   Due to their larger body size, rat feces are larger than mouse feces
   
   
   
   
   

Young rats vs. adult mice
I used to ask myself, "if the rat is still young, how could we differentiate it from adult mice which is about the same size?"

Well, the answer I got is;
Young, weaned rats are still larger than adult mice, weighing around 100 grams at six weeks. However, to the casual observer, very young rats and adult mice can be difficult to tell apart.

Feature	Baby Rat	Adult Mouse
Head	short, stubby, broad, large relative to body	small, triangular, small relative to body
Muzzle	large and blunt with wide muzzle	narrow with sharp muzzle
Ears	ears are small relative to the head	ears are large relative to the head
Tail	thick	thin
Tail/body ratio	Tail shorter than body	Tail same length/longer than body
Feet	Large relative to body, especially the hind feet	Small relative to body
Weight	around 100 grams at 6 weeks, 200 grams at 8 weeks	30-50 grams
	6 week old rat	Adult mouse

Referrences:
http://www.ratbehavior.org/RatsMice.htm
http://www.pestakill.co.uk/pest_information/pests.htm

Why Rodents?

Remember Ron Weasley’s pet rat – Scabbers – in the famous Harry Potter series? Although it may seem as though Ron is having a very easy time taking care Scabbers, having rats as pets actually requires considerable amount of work too.

Why Choose Rodents as Pets?

Rodents offer the best of both worlds for pet owners since they may be cuddled when a person feels like it and brought back to the cage when the owner is busy. Unlike cats and dogs which would require constant supervision – rodents are perfectly content occupying their small space for days provided there are more than one in a cage.

Keeping rodents take times, especially if they are not tamed or not commonly exposed to humans. Most of the rodents are territorial, (an exceptional to Heterocephalus glaber, which have a systematic hierrachy in their colony and few other species.) making them one of the hardest pets to be tame.

When we speak of rodents as pets, it definitely covers hamster, rats, mice, guinea pig, squirels, gerbil and even wild desert jerboa.
(note that sugar glider is not included, this is because they are MARSUPIAL)

Gerbils

• Gerbils live an average of 2-3 years
• They have a body length of about 4 inches, with a furry tail that is almost as long as the body (never pick a gerbil up by that tail, though!).
• Gerbils are very active and social so are happier as a pair or group (get all males or all females to prevent prolific breeding).
• Introducing new adults is difficult due to their territorial behaviour, though, so it is best to acquire a pair (or more) that are littermates or quite young.
• A recommended minimum cage size for a pair of gerbils is 12 by 24 inches, with a height of 12 inches, although more space would be better.

• With regular handling, gerbils can become quite tame, and are interesting to watch as they play an d interact with their cage-mates.

Mice

• May live 1-3 years on average, and are quite easy to keep.
• The smallest of this group with bodies that are only about 3 inches long, with a long hairless tail.
• They are also social and females do well in pairs or small groups (males tend to fight if kept with other males).
• Introducing new adults is difficult.
• They need a relatively small cage, minimum 12 by 18 inches (and 12 inches tall), although a larger cage is recommended if you have more than a pair.
• Mice can become quite tame if handled regularly but are small, fast and can be skittish so are not the best candidates for human interaction. However, they have low maintenance cost and quite active and playful, so they are entertaining to watch.

Guinea Pigs

• Guinea pigs are fairly long lived, with an average lifespan of 5-7 years (up to 10 reported).
  
• At an adult size of about 10 inches long and 2-3 pounds, they are also the largest of the commonly found pet rodents.
  
• Their size and gentle temperament have made guinea pigs popular pets, especially for families.
• They rarely bite, even when stressed. They are social so do best kept in pairs (same sex), and they need a larger cage than is typically found in the guinea pig section at the pet store.
• A suggested minimum is 4 square feet of floor space for a pair - and this is only if daily exercise outside of the cage is available. Larger cages can be easily created with household materials to create a wonderful habitat.
  
• Interestingly, guinea pigs are unable to synthesize vitamin C, and are prone to scurvy. Therefore vegetables or mixed feed with high vitamin C must be added in their diet.

Rats

• Rats live an average of 2-4 years, and make nice pets.
• They are very social, and it is best to keep a same sex pair (male or female).
• Since they are larger, with a body length of about 8 inches (and a hairless tail about the same), they are easy to handle.
• With regular handling they become very tame and enjoy human companionship, and they rarely bite.
• They need time outside of the cage for social interaction and exercise, and can even be taught simple tricks (they have even been compared to dogs in their ability to bond and interact with people).
• They do need a large cage: a tall cage with at least 24 inches by 36 inches of floor space is recommended.
• Due to their social nature they need more time and attention than many of the other small rodents, but make rewarding pets.

Hamster

• There are several species of hamsters that are widely kept as pets and each have their own characteristics and behaviors.
• The common species found in the market are ; Syrian, Campbell Russian, Roborovski Dwarf, Chinese, and Winter White Russian Hamsters

Other rodents that are kept as pets
(but rarely due to their low availability and overall costs)

Chinchilla

• Chinchillas live typically about 15 years, but 18-22 years is not uncommon.
• Body length about 10-14 inches; tail is another 5-6 inches or so.
• With gentle handling from a young age most chinchillas will become quite tame and bond closely with their owners
• Chinchillas can be kept singly, and usually will do fine as same sex pairs especially if they are litter mates or introduced at a young age.
• Chinchillas are prone to heatstroke. They dissipate heat by routing blood to their large ears, so red ears signal overheating.

Prairie Dog

• This stout-bodied rodents will grow to be between 30–40 centimetres (12–16 in) long, including the short tail and weigh between 0.5–1.5 kilograms (1–3 lb).
• Highly social, Live in a large colonies called town.

• Exhibit very interesting behaviors within their own colony, including kissing, burrowing and own a hierarchy within themselves.
  P.S : When I was sight-seeing not too long ago, I noticed that these prairie dogs are sold at Wakaf Che Ye, and Penang
  

Jerboa


Yes, they are cute, and some only an inch in size. However, the fact remains that little is known about the little critters, so what if he or she should become ill and need a veterinarian. Do veterinarians knowledgeable about the pygmy jerboa?