Studying marine creatures

The study of sea animals expands our understanding of biological life in aquatic environments. Today marks my first experience with sea animals in a laboratory. I feel overjoyed and overjoyed to be carrying out this experiment. The observations of two types of aquatic animals are revealed in the description below.
Urchins of the sea, also known as hedgehogs of the sea, are tiny, prickly, curved creatures that are closely related to sand dollars. They are members of the phylum echinoderm’s class Echinoidea. Approximately 950 echinoids species live in oceans from high tide to a depth of around 5,000 meters. Urchins of the sea has a cylindrical and spiky shell, which is usually from 3 to 10 cm across. It has typical colors, which are black, dim lush and blue. Urchins of the sea have slow locomotion, and they majorly feed on organisms that include sea otters and wolf eels. On the other hand, organisms of prey hunt urchins of the sea and feed on them. In various cuisines, they are a delicacy.

Urchins of the sea come from Kingdom Animalia. They fall under Phylum Echinodermata. They also originate from Subphylum Echinozoa and come from Class Echinoidea. Below are the steps to planning the sea urchins:

We need to pack the syringe with 1.5 ml of 0.5 M solution of potassium chloride.

Gently insert the needle into the tender tissue surrounding the mouth of the urchin and inject the solution into the central cavity.

Fig. 1

Wait about 10 minutes; egg cells will emanate from the gonophores in the aboral side.

Fig. 2

Ten minutes later, our group confirmed that the specimen was female sea urchin through the observation of yellow eggs.

Fig. 3

The sea urchin experiment was carried out according to the instructions. In the process of solving the plan, we observed the situation inside the sea urchin, its digestive and circulatory systems. Knowing the fact that the French and the Chinese have mastered how to cook the sea urchins, I once ate sea urchins in Sanya, China, ten years ago, and it had a really good taste.

Sea Сucumber

Cucumbers of the sea are echinoderms and emanate from Class Holothuroidea. Cucumbers of the sea possess a leathery skin texture. Their bodies are long and have single-branched genitalia. The primary habitat for cucumbers of the sea are the sea floors. Globally, the estimated count of holothurian species is approximately 1,717, with a high percentage in the Asia Pacific area. These species breed in numerous aquaculture systems. Additionally, they are collected as human food. When picked, the product is given another name – trepang, bêche-de-mer or balate. Cucumbers of the sea are vital in reusing nutrients in the ecosystem. They break down soil components, making further degradation easier for bacteria. Similar to other echinoderms, cucumbers of the sea possess endoskeletons right under the membrane.

Sea Cucumbers come from Kingdom Animalia. They originate from Phylum Echinodermata and are classified in Subphylum Echinozoa, Class Holothuroidea.

The surface skin of sea cucumber is very hard and slippery. Therefore, the first step is to keep it fixed.

Fig. 4

The second step is to begin to solve the sea cucumber from its mouth.

Fig. 5

The sea cucumber body will then break open, and we can clearly see its internal structure such as the digestive system. We can also examine how it is eating and how it excretes from the tube. The internal structure observed is shown below.

Fig. 6

Discussion; lessons learned and importance of the lab

From the first lab, we determined gametes’ production in female sea urchins. Although it is difficult to distinguish the difference between the male and female urchins, the specimen provided was female. The potassium chloride injected into its central cavity stimulates the gonad wall to contract. As a result, ripe gametes, which were yellow in color, sprung from surroundings of the anus on the organisms’ aboral side.

This production of egg cells is a key attribute of organisms which reproduce through sexual means. Mammals and urchins of the sea have the same sexual reproductive characteristics. Additionally, the shape and size of their egg cells are similar to that of human beings. This, therefore, makes the study of the urchins of the sea an intriguing inquest due to such similarities.

After deeply examining the sea cucumber’s digestive system, we discovered that a pharynx lies behind the mouth. A couple of ring plates surround the mouth. On further research, we determined that they are calcareous. The pharynx opens directly into the stomach in most cases, while in some instances they open forthrightly to the viscera. Its entrails is long and coiled in the body. It directly ends with the anus.


By studying the internal structure of the sea cucumber, we obtained a deeper understanding of their digestive system, including how food passes along from the mouth to the anus.

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