Comparison of Different Digestive Systems

Looking at the digestive system of the frog and the earth worm during the in class experiments we found out each organism has its own distinct anatomy. As we observed the earth worm the digestive system track was towards the mouth, anterior to the clitellum. Inside the digestive system of the earth worm it has the pharynx, the esophagus, the crop, the intestine and the gizzard. Food such as soil enters the earthworm'smouth where it is gulped by the pharynx.Inside the frogs, the mouth, the buccal cavity, pharynx, esophagus, stomach, small intestine, large intestine, and cloaca make up the digestive system. All these have the commonality of being able to store and digest food through there stomach.

Introduction

        In each of these organisms, the frog and the earth worm they have unique backgrounds from where they live to the type of environment they engage in and other organisms that live in the same niche as them. In our Biology 2 Lab we were told to dissect the earth worm and frog identify their internal and external anatomy. I specifically looked at the digestive system of each organism to understand the similarities and differences between them.

Earthworms began entering North America as early as the 1600s. Many of the earthworms today are found in common gardens deep underground are known as the Lumbricus terrestris. The earth worm's main food source are leaves, dirt and organic material (Morris 2013). The characteristics that make earthworms useful for there environment is that they stir up the soil, make nutrients accessible to flowers and vegetables. The fertilizer created by the earth worms helps in the agricultural environment.

        Frogs have been on earth for over 200 million years. Frogs have excellent night vision and are very sensitive to anything moving (Morris 2013). Frogs have thin skin through which they absorb chemicals from the air and water. Frogs main food source is mosquitos. Most wetland frogs have very limited tolerances for drying.

Materials and Methods

        For all three of these labs I needed a dissection kit. It was important to have a clean environment to begin the dissections. The first dissection I did was the earth worm, when I started cutting through the worm it had to be a gentle cut because if we cut too deep it would ruin the organs of the digestive system (Prete 2018). The frog had a harder outer layer and was cut from the ventral side up. When I dissected each organism, I had to pin down the skin so we can get a better view of the internal anatomy and a better view of the digestive system. For more detailed instructions on the dissections can be found on the dissection guides given.

Results

        All the organisms had interesting finding inside of their digestive system.  The earthworm's digestive system goes from the mouth to the intestine (Figure 1). The frog's internal anatomy included more commonly known organs such as the stomach, intestine, gall bladder, pancreas, esophagus and liver (Figure 2). These figures are placed at the end of the lab report.

Discussion

        The organisms that were dissected were the earthworm and the frog. These organisms have similar, notable features but are formed and placed in different sections within each body for adaptation features. For instance, the organs in the earthworm were the smallest and hardest to keep intact. It is, however, important to note that the digestive system of all the organisms had intestines in order for food to process. Each organism has its own way of metabolizing food. The environment that the earthworm lives in keeps the earthworm alive and sustainable to get food. The frog's environment of sustainability is the wetlands. The digestive system of the earthworm embodies an esophagus, gizzard, crop, and intestine. Lastly, the digestive system of frog has a much more enhanced system with the embodiment of a mouth, stomach, liver, gallbladder, intestine, esophagus and cloaca. The stated differences in these organism's digestive system is a result of evolution and occur as a response for them to better adapt in their environment. It appears that the earthworm has established itself to be the most primitive amongst the others and the frog being the most advanced. Frogs are amphibian that come from chordates phylum, while earthworm are from Annelida phylum (Andre 1999). Frogs are the most recently evolved animal compared to the earthworms.

The homologous features of the frog help it live in its habitat for example the forelimb of a frog helps it keep its balance and to be able to move around (Silver, 2015). Also, the earthworm's lungs are analogous to its skin. These organisms have analogous and homologous features that help them adapt into the environment that they are in. Although the frog and the earthworm have a digestive system that gives the same end result, they are complex and unique from one another. The main goal of these dissections was being able to identify the organs of each organism and comparing them among the three to see how they are arranged in the body and used.

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