Our Zoo Visit

Wrapping Up Our Adventures With Giraffes

To finish off our blog on giraffes we visited the giraffe exhibit at the San Diego Zoo.  We had a great time taking pictures and observing these beautiful animals! 

The giraffe in the background of the two above photos is one of the baby giraffes currently at the zoo.  She is only a year old and look how tall she is!

Our fun fact of the week came from one of the workers at the zoo.  She said that people always wonder why don't the giraffes don't just step over the short wall that is keeping them in? The reason for this is because on the other side of the wall there is a 3 foot deep moat.  Surprisingly giraffes don't like to step down more than 6 inches and because they would need to step down into this 3 foot deep moat to cross the wall makes the task seem to risky so they don't even attempt to escape.

At the zoo the giraffes eat from tall tree like structures and also from bins that contain their favorite food...acacia trees!

The picture above is of the only male giraffe at the zoo.  His name is Silver.  If you look closely at his coat pattern you can see that he is a Masai giraffe based on the distinct color and pattern.

And this is us say so long to our giraffe friends at the zoo!!  Thank you everyone for reading our blog.  We hope you enjoyed learning about giraffes just as much as we did!

Scholarly Journal Article

Grazing Behavior of the Giraffe in Hwange National Park, Zimbabwe

As mentioned in a previous post, acacia leaves make up a majority of a giraffe’s diet. Therefore, giraffes are typically classified solely as browsers. “Browsing” is foraging behavior that occurs when a giraffe stands upright, like when eating leaves from a tree (Seeber 248).  However, studies show that giraffes sometimes feed on grass and herbs at ground level, which requires them to assume the ‘drinking position’ where their front legs are spread apart so their heads can reach the ground. Peter A. Seeber and his team of researchers observed giraffe feeding behavior (for a total of 188 hours) from March to May 2011 in Hwange National Park, located in Zimbabwe (247). The team investigated how often grazing is part of giraffes’ feeding behavior, and recorded the number of grazing events observed as well as the duration of the grazing behavior.

Giraffe in Hwange National Park, Zimbabwe

Thirty-one instances of grazing occurred for a total of 174 minutes of grazing, which made up 1.5% of the total observation time (248). Interestingly, giraffes that did graze were almost always in groups, perhaps because the ‘drinking position’ makes giraffes vulnerable to predators. Seeber’s research illustrates that although not a primary activity, grazing does occur in a “nutrient-poor environment” like the Hwange National Park (247). Upon reviewing their results, the researchers concluded, “the function of feeding on herbs during the dry season is not principally to supplement protein/energy intake, but rather to access other nutritional factors not currently present in sufficient amounts in browse… because the herb layer sometimes has more available micronutrients than browse” (249). Further research about the micronutrient content in plants would supplement the research conducted at Hwange National Park.

Giraffe grazing in 'drinking position'

Work's Cited

Seeber, Peter A., Honestly T. Ndlovu, Patrick Duncan, and Andre Ganswindt. "Grazing Behaviour of the Giraffe in Hwange

      National Park, Zimbabwe."  African Journal of Ecology 50.2 (2012): 247-50. Wiley Online Library. Web. 25 Apr. 2012. 

     <http://0-onlinelibrary.wiley.com.sally.sandiego.edu/doi/10.1111/j.13652028.2011.01314.x/abstract;jsessionid=      

     8F1D66A9F273D7BA85E8F2E8453218CC.d03t03>.

A Giraffe's Tongue

Lick It All Up!

One distinct feature of giraffes is their tongues.  Their tongues are on average 18-24 inches in length, dark in color, and extremely tough.  These characteristics are what make the giraffe’s tongue advantageous to their eating habits.  Giraffes usually feed on Acacia trees, which have long thorns that can potentially be dangerous to animals trying to feed on them.  But not for giraffes! Because their tongues are so long they can reach the Acacia leaves without getting poked in the face.  The toughness of their tongues allows them to eat the leaves without getting cuts in their mouth.  The dark color of their tongues is also important because it prevents it from getting sunburned during feeding times.  The characteristics of a giraffes tongue are extremely important for their survival.

Fun Fact of the Week!: A giraffe eats hundreds of pounds of leaves each week and must travel miles to find enough food to fuel it’s body.

Works Cited

"Giraffe." National Geographic. Web. 01 May 2012. <http://animals.nationalgeographic.com/animals/mammals/giraffe/>.

"Mammals: Giraffe." San Diego Zoo's Animal Bytes: Giraffe. Web. 01 May 2012. <http://www.sandiegozoo.org/animalbytes/t-giraffe.html>.

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>.

Coat Patterns

Check Out That Cool Coat!

Giraffes have very distinct coat patterns. Even though there is only one species of giraffes, each of the nine subspecies has different coat patterns based on where they live. The differences between each species’ coat patterns are determined not only by where they live, but also by what they eat.

            A giraffe’s coat pattern acts as a fingerprint in the fact that each one is unique. It distinguishes them from other giraffes in the herd. The differences in coat pattern help young giraffes determine who their mothers are in a large herd because no two giraffes have identical coat patterns.

            A giraffe’s basic coat pattern consists of dark blotches, which are usually brown, chestnut, black, or orange in color. Light hairs that are usually white or cream in color separate these blotches to give the giraffe a distinct coat. Their coat pattern is used as camouflage in their environment, which is why their coat pattern is dependent on where they live. As a giraffe gets older, the color of his or her coat usually darkens, but the pattern stays the same. This is especially true for male giraffes.  

Here is an example of three subspecies of giraffes that all live in Kenya.  They each display unique coat patterns even though they live in similar environments.

The reticulated giraffe (Giraffa camelopardalis reticulata) is distinguished by defined bright patches, which are usually orange or brown in color.  Sharp white or cream lines separate these patches.

The maasai giraffe (Giraffa camelopardalis tippelskirchi) are the darkest subspecies of the giraffes.  Their coat is recognizable by its dark brown jagged edges with a cream or light brown color backgroud.

The Rothschild's giraffe (Giraffa camelopardalis rothschildi) is the most rare of the giraffe subspecies.  Its coat is similar to the maasai giraffe but it is much lighter in appearance.  It is known for the lack of dark color pattern below their knees

Fun fact of the week: Although this rarely occurs, some giraffes are born so dark or light in color that their spots are barely visible!