Trace the Evolution of Digestive Systems in the Animal Kingdom
https://www.youtube.com/watch?v=N3DgNbyz4as
Directions: Visit the website and answer the associated questions below for 35 points Please
post to the journals site
1. Describe how the earliest ancestors of animals obtained energy (was there presence or absence
of mouths or stomachs?)
They had no mouths or stomachs.
2. Ediacarans were first discovered where?
The coast of new finland
3. How did Ediacarans obtain energy?
They got their food from the water by absorbing it.
4. Are Ediacarans considered plants or animals?
They were the very first animals on earth.
5. The evolution of the first “guts” were most similar to the digestive system of what organisms
living today?
Jellyfish
6. During what period did the Ediacarans disappear (and why?)
The Cambrian explosion because of the new and more evolved organisms
7. The Cambrian creatures had what advantage over the Ediacarans?
Mobility and the more evolved way to eat or protect themselves.
8. How did the red worms (feeding on whale bone) derive their nutrients without a digestive
system?
They provided access to the bone for the bacteria inside them to breakdown the bone.
9. How do Bacteria, the first life form on earth, break down organic material?
They evolved enzymes to break down organic material.
10. According to the documentary, the symbiotic relationship between bacteria and animals has
developed more than once. Why is it hypothesized that this has happened?
Bacteria would find shelter in animal’s guts and they would break down what the animal could
not do themselves.
11. What was the advantage in the development of the stomach in fish? (over those with a simple
tube) (2 points)
It allowed the food to be passed in a specific order, so they could be more efficient about
breaking the food down.
12. 375 million years ago one lineage of fish made a remarkable leap and discovered how to obtain
resources where?
On land
13. How do birds break up their food with no teeth?
They use gastroliths or small stones they intentionally eat with their food
14. Which organ grinds up the gastroliths?
The gizzard
15. On the evolutionary tree, Tyrannosaurus rex lies between what two living species (“cousins”)?
Crocodiles and birds
16. What are coprolites?
Fossilized dinosaur feces.
17. Karen Chen at the University of Colorado, found what amazing discovery in copralites?( Besides
bone fragments).
To see what they were eating and how they ate; they had cold-blooded eating habits.
18. Does T rex food pass slowly or quickly through the digestive system?
It passed quickly through
19. Do warm blooded animals have food pass through quickly or slowly? What are the
consequences of this? (2 points)
They have food pass quickly and would need to eat more frequently.
20. Fast digestions means fast or slow metabolism?
It means fast metabolism
21. Why were dinosaurs not able to survive the asteroid that hit over 65 million years ago?
They could not survive a massive food shortage
22. How did Mammals survive the asteroid impact?
They would burrow under ground
23. What method of digestion did snakes evolve?
Does not chew its food and swallows the victims whole.
24. U of Alabama Steven Secor studies the evolution of Burmese Pythons. What has he found
unique in the snake gut? (what allows the constrictor to fast for months or years at a time?)
The digestive tract makes up of almost 90 percent of its body, increase of acids happens to break
down food as time goes by. They have an on off switch of the gut and save energy between
meals.
25. How are the microvilli in snake different from mammals? How does this benefit the snake?
They maintain their same length, same position, but they do change in snakes. They increase the
surface area in the gut to be able to consume large prey.
26. Twenty million years ago the earth began to cool. How did this change food sources for
herbivores? (think biomes)
Forests turning into grasslands
27. What was the nutritional problem with grassland replacing forests? (inability to digest what?)
The inability to digest grass
28. What group of organisms evolved to dominate the grasslands?
Cows or ruminants
29. What benefits did ruminants have over other organisms? How did this strategy allow them
protection? (2 points)
They could eat quickly and then go to a safe place to continue eating their food
30. What is required to digest cellulose?
A big colony of bacteria in the gut
31. What allowed man to develop a smaller gut?
A radical change of diet by making tools to get more meat and make them easier to eat.
32. What allows us to get more energy out of food with less effort?
Cooking it
Image: http://www.abc.net.au/news/image/7251586-3x2-940x627.jpg
Image: http://ocean.si.edu/sites/default/files/styles/blog_photo/public/photos/602P01G01Burgess_Shalew.jpg?itok=4TMvIoSX
Image;http://wuyeteke.com/wp-content/uploads/2015/01/1b82d-cebra-pelea-leon.jpg
Image: http://www.microscopy-uk.org.uk/mag/imgnov04macro/boa200.jpg
Powered by TCPDF (www.tcpdf.org)
