Comparative anatomy is a branch of biology that explores the similarities and differences in the anatomical structures of different organisms. When comparing the digestive systems of rabbits and frogs, distinct variations in their structures and functions become evident.
The rabbit, a mammal, possesses a complex digestive system suited for herbivorous feeding. The process begins in the mouth with specialized incisors to efficiently cut plant material. Saliva contains enzymes that initiate starch digestion. The food then travels down the esophagus into a multi-chambered stomach, allowing for microbial fermentation of cellulose-rich food. The small intestine is relatively long, enabling extensive nutrient absorption, while the cecum plays a crucial role in breaking down fibrous components further. This adaptation reflects their diet of plant material.
On the other hand, frogs are amphibians with simpler digestive systems suited for a carnivorous lifestyle. The mouth lacks teeth, but the sticky tongue efficiently captures insects and prey. Food moves down the esophagus into a stomach with two regions: the anterior section stores food and the posterior part carries out chemical digestion with acidic secretions. The small intestine is shorter than rabbits, and nutrient absorption mainly occurs in the duodenum. Unlike rabbits, frogs lack a cecum, as they consume easily digestible animal proteins.
| Rabbit | Frog |
|---|---|
| Omnivorous | Carnivorous |
| The Alimentary canal consists of mounth, buccopharyngeal cavity, pharynx, oesophagus, stomach (a. Cardiac part, b. Fundic part, and c. Pyloric part), small intestine (a. Duodenum, b. Jejunum, and c. Ileum), sacculus rotundus in rabbit, caecum, vermiform appendix, colon, and rectum. | The Alimentary canal consists of Mmouth, buccal cavity, pharynx, pharynx, oesophagus, stomach (a. Cardiac part, b. Fundic part is absent, and c. Pyloric part), small intestine (a. Duodenum, b. Jejunum is absent, and c. Ileum ), large intestine or rectum, cloaca, and anus. |
| Glands of alimentary canal are i. Salivary glands, ii. Mucous glands, iii. Gastric glands, and iv. Intestinal glands. | Glands of the alimentary canal are the following: i. Mucous glands, ii. Gastric glands, and iii. Intestinal glands. |
| Accessory digestive glands i. Liver, and ii. Pancreas | Accessory digestive glands i. Liver, and ii. Pancreas |
| Mouth opens laterally and is surrounded by lips. | Mouth opens laterally. It opens and closes by the lowering and raising the lower jaw as in all other higher vertebrates. |
| Teeth are in 2 sets i.e., milk teeth and permanent teeth. This type of teeth is called diphyodont. Teeth are with roots found in sockets and, therefore, are called thecodont. They are of different types, therefore, are called heterodont, the dental formula. | Teeth are present on upper jaw only. Teeth resemble those of Scoiiodon and are homodont, and pleurodont. Vomerine teeth present. |
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| Oesophagus is a slender straight tube, which leads on the pharynx to the stomach. It also secretes mucus, which helps in lubricating the food. | Oesophagus is not sharply distinguished from either mouth or the stomach. Mucous glands are found in oesophagus. |
| Stomach is pear-shaped. Large, circular structure. It is distinguished into three parts - the cardiac part, the fundic part and the pyloric part. There are three types of gastric glands. a. Cardiac, b. Fundic, and c. pyloric. | The stomach is a simple tube and consists of cardiac and pyloric. Gastric glands are present in stomach. Pyloric sphincter is also present, which separates stomach from intestine. |
| Length of the small intestine is greater and it is much coiled. The small intestine is provided with a large number of villi. There is also a ileo-coelic valve between the small intestine and the large intestine. | Intestine is small. Its lining is not provided with either scroll valveor villi. Duodenum is a U-shaped structure Small intestine is in a few coils. |
| There is also a caecum with scroll valve which is the first part of the large intestine. At the terminal end of the caecum is an appendix. Colon is followed by rectum. | Large intestine through rectum leads into the cloaca. There is a great distinction between large intestine and small intestine. |
| Liver is the largest digestive gland. In rabbit it is five-lobed. The bile-duct receives branches from each lobe. The bile from bileducts is poured into the duodenum. Glisson's capsule is present. | Liver is well-developed, made up of 3 lobes. Gallbladder is a rounded sac which stores bile. Common bile-duct is opens into the duodenum. |
| Pancreas is a diffused gland with small lobules. There are several pancreatic ducts, which open into the bile-duct. Pancreas is endocrine gland. In it are islets of langerhans which produce insulin. | Pancreas is a cream-coloured, compact gland made up of small lobes situated between stomach and through the pancreas, called common bile-duct or hepatopan-creatic duct. |