The Stomach of a Giraffe

Chew On This!

Giraffes have a diet high in plant material, which is hard to breakdown.  Because of this, giraffes have a special four-chamber stomach that allows them to breakdown the tough plant material and allow them to obtain the nutrients from it.  The four-chambered stomach has four compartments: the rumen, reticulum, omasum and abomasum.

The first two chambers, the rumen and the reticulum, mix the chewed up plant material with saliva, which is then separated into solid and liquid waste.  The solid waste forms a cud that is regurgitated and then further broken down by the giraffe from chewing. The job of the omasum is to absorb water and other nutrients into the blood stream that were not absorbed in the rumen or reticulum. Once the food has been chewed up again and further broken down by saliva in the mouth, it then moves to the true stomach: the abomasum.  The abomasums breaks down the remaining food material in the same way that our stomach breaks down our food as humans.  From here, giraffe’s food is digested in the same way as ours by moving through the small and large intestine where nutrients are further absorbed.  Although the process of a four-chambered stomach is complex, it is essential for a giraffe to obtain all of the possible nutrients out of its plant-based diet.  The workings of a four-chambered stomach allow the giraffe to do this in the best way possible.

Fun Fact of the Week!: A giraffe only sleeps for 1-12 minutes at a time and usually gets about 30 minutes total in one day!

Bowen, R. "Digestive Anatomy in Ruminants." Arbl.cvmbs.colostate.edu. 23 Nov. 2003. Web. 20 Apr. 2012. <http://www.vivo.colostate.edu/hbooks/pathphys/digestion/herbivores/rumen_anat.html>.

"Mammals: Giraffe." San Diego Zoo's Animal Bytes: Giraffe. Web. 20 Apr. 2012. <http://www.sandiegozoo.org/animalbytes/t-giraffe.html>.

Hard-working Hearts

The Heart of the Matter

Because giraffes are so tall, their hearts must be capable of pumping blood at a high enough pressure to flow up through their necks and into their brains. For this reason, a giraffe’s heart has special adaptations to overcome gravity. A giraffe’s heart can weight up to 25 pounds, and is several inches thick, making it very powerful. Additionally, a giraffe’s heart pumps around 16 gallons of blood per minute!

Giraffe heart

These strong hearts also produce an average blood pressure of 280/180, which is twice the pressure of other large mammals, and more than twice the recommended human blood pressure of 120/80. This high blood pressure is necessary for blood to reach the brain, but could be dangerous when a giraffe lowers its head. For this reason, giraffes have a pressure-regulating system made up of small blood vessels called “rete mirabile,” anti-pooling valves, and reinforced artery walls. This complex system prevents excessive amounts of blood from rushing toward a giraffe’s brain when it lowers its head. The jugular veins in giraffes also have valves that stop blood from flowing backwards into the head when its lowered. 

Interesting fact of the week: Giraffes have heart rates of around 150-170 beats per minute!    

Work's Cited

Bourton, Jody. "Supercharged Heart Pumps Blood Up A Giraffe's Neck." Earth News. BBC, 20 Nov. 2009. Web. 08 Apr. 2012. <http://news.bbc.co.uk/earth/hi/earth_news/newsid_8368000/8368915.stm>.

"Facts About Giraffes." About.com: Animals / Wildlife. Web. 05 Apr. 2012. <http://animals.about.com/od/hoofedmammals/a/tenfactsgiraffes.htm>.

"Giraffes- All You Never Wanted to Know." Squidoo. Web. 08 Apr. 2012. <http://www.squidoo.com/giraffes-all-you-never-wanted-to-know>.

Differences Between Males and Females

Battle of The Sexes

     When you look at a male and female giraffe they are almost impossible to tell apart, except for the fact that males are bigger than females. Here are a couple of distinctions between male and female giraffes that we found interesting:

     Male giraffes weigh about 3,500 pounds and females weigh about 1,800 pounds. Both male and female giraffes range between 16-20 feet tall. The males are usually taller than the females.

     The distinct horns (technically called ossicones) on a giraffe’s head differ between sexes. Female ossicones are usually covered in hair, while the male ossicones are bald on top. To establish dominance, males engage in a behavior called necking. Males will swing their necks and use their horns to hit another male for access to fertile females. With increased impact, the hairs on males’ ossicones wear down. Because females rarely fight, their hairs remain in tact.

           

              Female                                                                       Male

          

     

     Males develop calcium deposits that form bumps on their skulls as they age, which makes it look as though they have additional horns. These calcium deposits help to protect a male's head during a fight.

     Female calves (young giraffes) usually remain close to their original home range once they grow and mature. Male calves are more likely to migrate to other herds away from their home range.

Interesting Fact of the Week: Giraffes are the only animals born with horns. 

Works Cited

"Facts About Giraffes." About.com: Animals / Wildlife. Web. 05 Apr. 2012. <http://animals.about.com/od/hoofedmammals/a/tenfactsgiraffes.htm>.

"Giraffe - The Facts." Nature-Wildlife. Web. 05 Apr. 2012. <http://www.nature-wildlife.com/girextra.htm>.

"How Do You Tell The Difference Between a Male Giraffe and a Female Giraffe?" Blog Spot. Web. 05 Apr. 2012. <http://myfloatleft.blogspot.com/2010/04/how-do-you-tell-difference-between-male.html>.