Nutrition
The Okapi (Okapia johnstoni) is one of the most unique animals
on the face of the planet. This uniqueness is also found in
their dietary habits and their food source. The Okapi are found
in the rainforests of the central Congo, so their diet is
entirely based upon the foliage that can be found in the forest.
The Okapi is unique in the fact that it is strictly an herbivore
with a strictly foliage based diet (Hart, 2009). The Okapi will
only dine on the leaves of lower level plants around the Congo.
It will rarely, if ever, eat things such as berries, twigs, and
bark in the wild. But, if in captivity, the Okapi can be fed
grains along with leaves to supplement their diet (Okapi Fact
Sheet, 2009). Many animals have their “favorite” foods such as
the eucalyptus plant for the
koala, but the okapi does not have
a single favorite type of leaf to eat. The okapi, a solitary
animal, will wander around its habitat feeding from the leaves
of over one hundred different species of trees and shrubs (Hart,
2009)! The reason that the okapi does this is to reduce the
amount of a specific toxin it is ingesting. Many plants in the
Congo produce toxins to discourage herbivores from eating their
leaves (Hart, 2009). If too much of one kind of leaf is
ingested, the toxin levels would build up and the animal could
possibly die. The okapi avoids all of this, simply because it
eats very little amounts of many different kinds of plants. On a
typical day the okapi will ingest about four to five kilograms
of leaves (Okapi Fact Sheet, 2009).
One may think that this makes the okapi a very
diverse feeder, which is true to an extent, but the okapi are
also very picky eaters. They are choosy about what leaves it
will eat and which plants it will eat leaves off of. The okapi
only consumes leaves from woody plants. It will pass up leaves
from non-woody and large leaved herbs along the forest floor
(Hart, 2009). After the okapi has found a plant that it would
like to eat from it will even be more selective on which leaves
it will eat off that plant. The okapi will only eat fully mature
and healthy leaves off a plant. The okapi will rarely eat
immature leaves and will never eat older, dying leaves. If the
leaf is covered in something like algae or a moss the okapi will
pass it up (Hart, 2009). There are very few things that the
okapi will eat besides leaves. It may eat clay, burnt charcoal,
and bat guano to supplement some vitamins and minerals if needed
(Okapi Fact Sheet, 2009). These things make the okapi one of the
most diverse and picky eaters in the animal kingdom.
The okapi has several evolved attributes that help eat and
maximize the amount of energy absorbed out of the food it
ingests. One of these are that the okapi has developed is its
ruminant digestive system (Hart, 2009). The okapi has a rumen
which stores bacteria that can break down cellulose along with
several stomachs to further digest plant material. The okapi
also regurgitates some of its food so it can re-eat it and give
it one more chance to be digested even more. The okapi’s cud
(thrown up material) is seen as extremely repulsive to other
herbivores, even other ruminants (Hart, 2009). This gives a huge
advantage to the okapi. If
the okapi regurgitates and doesn’t
have time to eat it, the animal can always return later without
having to worry about it being eaten later. Another adaptation
can also be found in the okapi’s close relative, the
giraffe.
This adaptation is the presence of an extremely long tongue
(Hart, 2009). This long tongue is used to strip leaves off of
plants without the need to bite. This allows the okapi to get
leaves off branches without biting off any of the branch ends
along with the leaves.
The okapi has a very highly adapted digestive system to
help it deal with its’ strictly leaf diet. Their digestive
system is very good at breaking down cellulose but not nearly as
efficient at breaking down starch and other sugars. This was
shown in a study in which the urine of okapis was analyzed for
the presence of proteins, glucose, bilirubin, nitrates, blood
and ketones. The pH of the urine was also taken. There was an
excess amount of glucose in the urine showing that the okapi was
very inefficient at digesting glucose (Glaston, 1980). A young
okapi does not defecate for about the first month of its life.
This is due to the fact that the young okapi just lies in one
location for about a month while its mother forages. The mother
only returns briefly to nurse the young (Hart, 2009). The okapi
will begin to eat leaves at about three weeks and will start to
ruminate at about six weeks. The okapi are well suited to
survive in its environment due to its ruminant digestive system,
long tongue, and ability to not defecate for a month to help
conceal its location during its young years.