How is the Frog Digestive System Different from Humans

Both frog and human digestive system bear mostly similar anatomy. However, the frog digestive system is different from humans in some aspects. Frogs have two sets of teeth while humans have a single set of teeth. Frogs have a shorter small intestine than humans do. Instead of rectum and urethra, frogs have a cloaca. The frog has its tongue connected to the starting point of the mouth. Moreover, frogs do not have an appendix. In this article, you will learn how is the frog digestive system different from humans by a side-by-side comparison of the features of both.

Frogs are a type of amphibians that live in both land and water. The digestive system of frog and human is a hollow tube, which aids in the ingestion and digestion of food, absorption of nutrients, and the elimination of undigested materials.

Key Areas Covered

1. What is Frog’s Digestive System
      – Anatomy, Function
2. How is the Frog Digestive System Different from Humans
     – Difference Between Frog and Human Digestive System

Key Terms: Cloaca, Deglutition, Frog Digestive System, Small Intestine, Teeth, Tongue

What is Frog’s Digestive System

The digestive system of a frog composes a mouth, pharynx, esophagus, stomach, small intestine, large intestine, and cloaca. The accessory organs found in the frog’s digestive system are tongue, teeth, salivary glands, gastric glands, pancreas, liver, and gallbladder.

Mouth

Mouth is the starting point of the frog’s digestive system, and aids in the capturing of the prey. The prey of frogs can be insects, flies, spiders, slugs or worms and it moistens the prey with its saliva.

Pharynx and Esophagus

The mouth connects to the stomach through the pharynx and esophagus.

Stomach

The muscular sac found at the end of the esophagus is the stomach. It stores food, and the enzymes secreted from the stomach are responsible for the chemical digestion of food. The muscular action of the stomach is responsible for the mechanical digestion of food. Pylorus at the end of the stomach opens the stomach to the small intestine.

Small Intestine and Accessory Organs

The absorption of nutrients occurs in the small intestine. The two parts of the small intestine in frogs are the duodenum and ileum. Bile and pancreatic juice, the digestive fluids produced by the liver and the pancreas respectively, are secreted in the small intestine. Liver is the largest organ in the body cavity of the frog. Gallbladder is the reservoir of bile located under the liver.

Large Intestine and Cloaca

The undigested food is stored in the large intestine, absorbing water from them. The solid wastes move towards the cloaca. The urinary bladder also opens into the cloaca. The anatomy of a frog is shown in figure 1.

Figure 1: Frog Anatomy
1. Right atrium, 2. Liver, 3. Aorta, 4. Egg mass, 5. Colon, 6. Left atrium, 7. Ventricle, 8. Stomach, 9. Left lung, 10. Spleen, 11. Small intestine, 12. Cloaca

How is the Frog Digestive System Different from Humans

Though most components of the frog and human digestive system are similar, there are some differences in terms of anatomy as well as function. Generally, frogs do not drink water, and the absorption of water to the body occurs through the skin. These differences are described below.

Teeth

Frogs do not have strong teeth like humans. They use their teeth only for holding the prey, unlike humans. They swallow the prey without chewing through a process known as deglutition. During deglutition, frogs blink or close their eyes. Frogs have two sets of teeth while humans have a single set of them. The two sets are maxillary teeth, which are located in the jaws, and vomerine teeth, which are located in pairs of tiny clusters on the roof of the mouth.

Tongue

The tongue of a frog is attached to the starting point of the mouth, while in humans, it is attached to the back of the mouth. The tip of the frog’s tongue folds backward, aiding the capturing of prey. Moreover, the tongue of the frogs is very sticky.

Small Intestine

Frogs have a shorter small intestine than humans. The two parts of the small intestine of frogs are the duodenum and ileum. However, humans have three parts of their small intestine: duodenum, jejunum, and ileum. In frogs, the duodenum involves in the digestion of carbohydrates, proteins, lipids, and nucleic acids. The absorption of nutrients occurs in the ileum. However, in humans, absorpton of nutrients happens in the jejunum.

Elimination of Undigested Materials

In addition to the rectum and the urethra of humans, the elimination of frog’s undigested materials occur through the cloaca. The elimination of both undigested solid and liquid wastes happen through the cloaca. The urinary bladder also opens into the cloaca since frogs do not have a urethra. Moreover, frogs do not have an appendix.

Conclusion

Frogs digestive system shares many similarities with the human digestive system in terms of anatomy and function. However, there are some differences between frog and human digestive systems such as the presence of two sets of teeth in frogs, the sticky and folded tongue at the tip, the presence of a shorter small intestine, the presence of a cloaca apart from a rectum, and the absence of an appendix.

Reference:

1. “Digestive System of a Frog Aptly Explained With a Labeled Diagram.” BiologyWise, Available here.

Image Courtesy:

1. “Frog anatomy tags” By Jonathan McIntosh – Tagged version of Image: Frog anatomy.JPG (CC BY 2.0) via Commons Wikimedia