6.10: Digestive Detective Activity

Instructions \(\PageIndex{1}\)

1. Check out your case file. In your group, you'll get one of five case files and a bunch of clues — all pointing to a specific animal species.
2. Determine the animal. Go through the clues together as a group and see if you can figure out which animal your clues are describing.
3. Answer the follow-up questions. Once you've landed on an answer, complete the three worksheet questions about the digestive system details from your clues.
4. Pass it on. Done? Pass your case file to the next group and pick up theirs. Keep going until every group has looked at all five cases.
5. Submit your worksheet. Once you've been through all five, upload your findings to the assignment drop in BrightSpace.
6. Class discussion. Get ready to share! We'll talk through which animal you picked for each case and what clues tipped you off.

Case Files and Clues

1. Field Report: Researchers observed this animal grazing for hours and later re-chewing without any additional food intake. It produces large amounts of saliva and methane-rich belches. Dissection revealed four stomach compartments and VFAs in the bloodstream.

• Rumen, reticulum, omasum, and abomasum are present.
• Fermentation occurs before the small intestines.
• VFAs are the main source of energy.
• Regurgitates and re-chews food (cud).
• Relies on microbes for cellulose digestion.

Suspect animal:

1. What digestive system type is this?
2. What is the function of each compartment?
3. Why can this animal survive on low-quality forage?

2. Field Report: This animal grazes small amounts all day. Its stomach is small and simple with no gallbladder. The cecum and large colon are massive and full of microbes. It produces bacterial protein but absorbs little.

• Monogastric stomach with reduced muscular activity.
• Hindgut fermentation in the large intestine and cecum.
• VFAs are produced in the hindgut, not the foregut.
• No gallbladder (continuous bile flow).
• Prone to colic and digestive disturbances.

Suspect animal:

1. Why is its hindgut so large?
2. How does its digestion differ from a cow's?
3. Why can’t it use microbial protein effectively?

3. Field Report: This animal roots with its snout and crushes food with its teeth. Its saliva has amylase, and digestion relies on its own enzymes. Protein and fat digestion occur mainly in the small intestine.

• One-chambered stomach.
• Autoenzymatic digestion predominates.
• Saliva contains amylase (minimally effective).
• The pancreas secretes enzymes and bicarbonate.
• An omnivorous diet of plants and meat.

Suspect animal:

1. What enzymes are key to digestion?
2. Why does salivary amylase play a small role?
3. What organ neutralizes stomach acid for intestinal enzymes?

4. Field Report: This creature lacks teeth but swallows pebbles for grinding. Food is stored in a crop, partially digested in a proventriculus, and ground in a muscular organ before passing through paired ceca.

• Crop → Proventriculus → Gizzard → Small intestine → Ceca → Cloaca.
• No mastication in the mouth.
• HCl and pepsin are secreted in the proventriculus.
• The gizzard handles mechanical digestion.
• Two ceca ferment fiber near the large intestine.

Suspect animal:

1. How does it compensate for no teeth?
2. What does the ceca contribute?
3. How is waste elimination unique?

5. Field Report: This high-altitude grazer eats coarse plants and stores food in three stomach chambers. It chews cud like a cow but has a smaller rumen. Microbial fermentation efficiently produces VFAs and vitamins.

• Three-chambered stomach (missing omasum).
• Adapted to sparse, high-altitude forage.
• Alloenzymatic digestion by microbes.
• Chews cud, produces VFAs.
• Foregut fermentation before the small intestine.

Suspect animal:

1. How is it both like and unlike true ruminants?
2. What are the fermentation benefits here?
3. Why is this ideal for its environment?