April 26, 2019

Embryology

What am I?

Why do bird embryos have gill slits?On pg. ____ of your SINQ on the IP: Embryologic Similarities Chart (yellow/gold sheet), in the "before instruction" column, write: • 2 observations/answers• 2 questions related to this phenomena

April 26, 2019

Do only chicks go through an embryonic stage, or do you think other animals go through this process as well?

Most multicellular animals that undergo sexual reproduction will go through a growth cycle starting with an embryonic stage.

How similar do you think embryos are for different animals?

Chicken Development What is an embryo?

a developing organism before it is born

1. Put yourselves in order of embryonic development. 2. Record your answers to the questions on the

Chicken development page of your SINQ.

Organizing EmbryosPair share- can you define the following words? (remember, you can't use a word in its own definition!) • embryological development• species• anatomy

• Embryological development – Developmental changes of an embryo from fertilization to the fetus stage

• Species – A group of organisms with similar characteristics that are able to interbreed or exchange genetic material

• Anatomy – Study of the structure of animals and their parts

April 26, 2019

Organizing Embryos Directions1. Sort the cards by organism.2. Then sort each organism set by stage of development.

(Hint: There are five stages for each species.)3. Using the letters that indicate each stage of development, fill

out the data table on your lab sheet.> Note: Skip the “Animal column for now. That will be filled in

during step 5 when you get the Identity Cards.4. Part 2:

> Make a 5x5 grid of the cards. (Line up the 5 rows of cards so that all “Stage 1" cards are in a column, “Stage 2" cards are in the next column, etc.)

> Evaluate each stage to see where the organism characteristics diverge. Each time there is a divergence, this will indicate a different species. Take note of how long each organism looks similar to others, or when at (which stage) it branches off. Discuss with your teammates and be prepared to share with the class later.

5. Part 3: When you are done sorting and recording, come to me to get a set of five Identity Cards. Match the animal with the set of image cards that you think it belongs with.

> NOW fill in the “Animal column" on the data table. 6. Complete the reflection questions.

Organizing Embryos Discussion

1. Where did you find the different organism diverged in their development?

> Urchin diverged at stage 2, shark and frog were similar but not identical, chicken and mouse stayed similar longest.

2. Based on your findings, which two organisms would you conclude are the most similar out of the five you studied?

• The mouse and chicken have the closest relationship of the

5 presented because they have the most shared characteristics through their embryonic development.

3. Why do you think scientists study the embryological development of different species?

• Comparison of the embryological development of different species also reveals similarities that show relationships not evident in the fully formed anatomy.

April 26, 2019

Organizing Embryos Discussion Cont'd3. How do the anatomies of the mouse and chicken compare?

• Answers may vary. For example: The mouse and chicken embryo both formed four limbs. The mouse’s limbs developed into four legs while the chicken’s limbs developed into two wings and two legs.

How does “comparative anatomy" fit into this?

4. Both mammal and fish embryos contain gill slits. Similarly, whales, some snakes, and land animal embryos all exhibit hind limbs. How do the similarities in these developing organisms show relationships not evident in the fully formed anatomy?

• Linear relationships exist between mammals and fish even though that may not seem to be the case when just examining the fully developed anatomy. Linear relationships also exist between whales, some snakes, and land animals. Fully developed mammals lose their gill slits and fully formed whales and snakes lose their hind limbs.

Comparative Embryology ActivityComplete the comparative embryology paper with your partner. Turn it into your teacher when you're finished.

Then go back and double check that you finished filling in the peach footprint graphic organizer.

April 26, 2019

Embryologic Phases

What similarities and differences do you notice about these organisms?

April 26, 2019

Embryology

• Embryology is the science of development of embryos from fertilization to birth

• Comparative embryology is the comparison of different animals in various stages of embryonic development. • Studying embryonic development can show evolutionary relationships• The more closely related two species are, the more features they

share during embryonic development. (Biologists have theorized that this is due to their relation to a common ancestor)• As new structures evolved these would have been tacked onto the end stage of embryonic development so as not to disrupt normal organ system development and other complex body systems.• In the early stages of animal development (embryos) there are

structural similarities that are not found in the adult form of the organism

Embryology

Wealsoseeotherstructuresthatappearearlyindevelopmentwhichlaterdisappearordiminish.

Snakehindlimbbud.Whaleembryohindlimbbud.

Comparative embryology video

April 26, 2019

“Ontogeny recapitulates phylogeny”

• Ontogeny- development/ structural change• Recapitulates- follows• Phylogeny- evolutionary relations

•·Biologist Earnest Haeckle• During development, each embryo passes through several of the embryonic stages of their ancestors

Go back to your yellow/gold Investigative Phenomena sheet on pg. ________

On the "after instruction" column, summarize, in one sentence, how this phenomena why bird embryos have gill slits.