MIXED PLATE BIOLOGY, HAWAIIAN STYLE: BALUT EMBRYOLOGY
(Where in the World is Chicken Little?)
Submitted by: Jacquelyn Wesolosky
Roosevelt High School
Honolulu, HI
In the Filipino community in Hawaii, "baluts
" are considered a real culinary delicacy. The preparation of the balut
eggs involves the incubation of fresh fertilized chicken eggs for approximately 7
days. The eggs are then boiled for approximately 30 minutes and best when eaten
hot as you would eat a hard boiled eggs. Duck eggs may be substituted if you have
an available source. However, chicken eggs are preferable because of the prestigious position chickens hold in the Filipino communities as witnessed by the popularity of the infamous "cock fights". Baluts are generally available at these festive events.
In the Balut
embryology lab, we draw on an old traditional biology exercise but in a rather nontraditional
way. In this lab the students will see how animals develop from just one cell.
To watch the cells specialize and differentiate, we follow very careful procedures. Hopefully our end result will progress beyond the "balut
ready" phase to a walking, chirping "Chicken Little."
Teacher Note:
Before beginning this activity, be sure to secure suitable homes for the hatchlings.
MATERIALS:
fresh fertilized eggs fertilized for three days (1 doz. per class)
egg incubator (1 for every 2 classes)
PVC pipe containers or wide mouth plastic cups
handiwrap
alcohol and cotton
sterilized petri dish covers
marking pens
PROCEDURES:
- Set up your culture chamber: Place handiwrap (be sure you use this brand) into
the PVC pipe so that you have a "nest" for your developing embryo and secure it with
the clamp. Keep the petri dish sections together and label the cover with your chickens name and your group identification symbol.
- Select an egg from the incubator. One student should monitor the incubator as
the lid is difficult to maneuver and we want to keep the heat as constant as possible.
- Swab each egg with 70% alcohol to limit bacteria contamination. Swab the handiwrap also.
- Allow the egg to remain in a horizontal position for a minute or two to dry and
to allow the yolk to rotate so that the embryo will be on the top of the egg.
- Crack the shell with a sharp blow on the lower surface of the egg (or use other
techniques that you have practiced). Place the contents of the egg gently into the
handiwrap depression by separating the two halves of the shell, much as you would
place an egg into a frying pan for "sunny-side-up" eggs. If the egg was not fertilized
then try again with another egg. The person in charge of the incubator should make
sure that each class has at least 4 eggs remaining with shells intact so that we
can see the hatching process in 21 days.
- Place the petri dish lid on the culture chamber.
- Observe and then return the cultured egg to the incubator. Make observations
each day.
NOTE: Care should be taken to disturb the embryos as little as possible. Since cooling
will adversely affect development, keep the embryo out of the incubator for no longer
than is necessary. If observation exceeds 2 minutes, position a lamp with a 25 watt bulb above the chamber. The heat will keep the embryo warm until you return
to the incubator. KEEP THE CHAMBER COVERED WITH THE PETRI DISH TO AVOID BACTERIAL CONTAMINATION. If you have friends who wish to visit the "nursery" be sure that you accompany them as you know the procedures.
GUIDE TO YOUR OBSERVATIONS:
Each day we will make observations and drawings (portraits) of our "chicks". There
will be chicks at different stages of development from each class and we can all
share once we have them set up. If your chick does not make it through the night,
"adopt" another groups' chick -- this is an ohana
(family) project.
The first day you see the chicken it has been incubated for three days already - so
some research on the first three days will be essential. In the early stages locate
the albumen, yolk, chalaza
and the blastoderm
. The albumen is a clear liquid that occupies most of the egg and is composed of
protein. The yolk is obvious and composed of fats. (Why do you think this is important?)
The chalaza is a white twisted cord attached to both sides of the yolk. (What function do you think the chalaza has?) The blastoderm can be seen on eggs tha
not developing - on developing eggs you will see the actual embryo. Locate the head, heart, eye, spinal cord, somites, blood vessels
and notice how they change from day to day. Measure the length of the embryo in mm,
but eyeball this because you don't want to lift the petri dish cover.
At about 5 days locate the yolk sac (any change in size or shape?), the allantois
, and the amnion
. The allantois is a small, round membrane at the posterior end of the embryo an
the amnion is a thing membrane surrounding the embryo. Again, measure the embryo
and see if you can see the limb buds
. In succeeding days note changes in all pats of the developing chicken - the amniotic cavity
will become more obvious with time. How is this chicken eating, giving off waste,
and how does it move?
FINAL PROJECT:
Scrapbook to contain:
- A set of portraits for your chick at each major stage of development
- A new vocabulary: New terms are introduced above. Also include ectoderm, mesoderm,
and endoderm.
- Story in first person (as if you are your chick) about how you grow from the fertilized egg stage until you jump out of your shell
- A bibliography
REFERENCES:
Edra, Teri. Personal Communication. Buyer for Puuhale Market. 345 Puuhale St.,
Honolulu, Hawaii.
Scadding, Steven R. February 1985. How to Culture Chicken Embryos in Plastic Wrap Suspension.
The American Biology Teacher
, Vol. 47:2.
This is one of six lessons in "MIXED-PLATE BIOLOGY, HAWAIIAN STYLE", a collection
of biological activities that values the cultures of modern Hawaii's multicultural
population. The collection includes:
Hawaii is a land of immigrants. The Hawaiians are believed to have arrived around
1000 AD from the Marquesas Islands in the South Pacific. Starting in the 18th century,
Europeans and Americans arrived usually involved in missionary work or seafaring trades. Once agricultural plantations of sugar and pineapple were established in the
20th century, workers arrived from China, Japan, Puerto Rico, Portugal, and the Philippines.
Since the plantation days, immigration has been largely from Southeast Asian nations of Vietnam, Laos, Cambodia, and Thailand; Korea; the South Pacific nations
of Samoa and Tonga; the Philippines; as well as the U.S. mainland. As ethnic diversity
increases in our classrooms, let's draw from the various cultures to personalize
the concepts of biology.
(About the title: a Mixed Plate is a unique lunch that evolved as new immigrant populations arrived in Hawaii and can include pork adobo from the Philippines, teriyaki beef
from Japan, kim chee from Korea, bean soup from Portugal, chow mein from China,
traditional Hawaiian foods such as lau lau and poi and of course two scoops of rice.)
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