🐟 Dissecting the Fish 🔬A Journey Through Its Body

🔧 What We Need to Prepare
Before we begin, we must prepare our tools like true scientists and with great respect for the life we are studying.

🧰 Materials:

• 🧤 Gloves – to handle the specimen with care and cleanliness

• ✂️ Scissors, 🔪 scalpel, and 🔎 tweezers – for precise and delicate cutting

• 🪵 Table mat – to protect the workspace

• 🧫 Dissection tray – where we will place the fish and display the organs

• 🏷️ Strips of paper and pen – to label each organ

• 🐟 Fish for dissection – fresh or preserved, handled respectfully

👁️ Part 1: Observation – What We See on the Outside

We begin, not by cutting, but by observing the body of the fish. 👉 It’s smooth, slippery, and covered in tiny overlapping scales – from Latin squama, meaning “scale.” The scales go only one direction—smooth one way, rough the other.

But what about the head? Touch it—it’s smooth and bare. Do you notice something different? No scales there! Why do you think?
📚 The fish’s body is divided into three parts:
Head 🧠 where the brain and the gills are located.🐟 Trunk where the organs work. Tail 🐠 that pushes it forward.

Look at the eyes 👀—they stare without blinking. Why? Fish don’t have eyelids. Water moves over the eyes, cleaning them constantly. Behind the eyes, we see the gills—red and feathery. From Latin branchia meaning gills, they take oxygen from water, like breathing underwater. Along the fish’s body, there’s a special line—the lateral line. It’s like an underwater radar 🛰️.It senses movement and vibration. A sixth sense!🔪

🐠 Now, look at the fins—together, they form a movement system more complex than any machine. They don’t just help the fish swim—they help it survive. Turn sharply to avoid danger. Stop suddenly to hunt. Hover to inspect something or swim fast or slow depending on need.🧠 Each fin works like part of a team. Together, they make the fish not just a body, but a navigator.

🧭 Pectoral Fins are located just behind the gills, one on each side. Used for steering, like the handlebar on a bicycle. Also help the fish to brake or even hover in place.

🏄 Pelvic Fins are found underneath the body, toward the front of the belly. They help the fish stay balanced in the water and make up-and-down movements.

The tiny sail, that sticks up on top of the back is the ⚖️Dorsal Fin. It keeps the fish from rolling over in the water. It’s a stabilizer—like a keel on a boat.

🎯Look at the Anal Fin which is located on the bottom, near the back of the fish, just before the tail. Works with the dorsal fin to prevent rolling and maintain stability. 🟢 Most fish have an anal fin, but some do not—or it may look different depending on the species.

🚀Caudal Fin or the Tail Fin is very powerful fin at the very end of the fish. It provides thrust to move the fish forward. Fish have different caudal fins, depending on their style of swimming.

Can you tell if this fish is male or female? Sometimes, we can tell the difference between a male and female fish by looking at their fins, their colors, or their size. In some kinds of fish, the male has longer or more decorated fins, or brighter colors. But in others, the difference is hidden inside. Not all fish show their gender on the outside!

Part 2: The First Cut

Now we begin the dissection. We must be slow, careful, and respectful. Start near the anus from Latin anulum, 'little ring .This small opening near the tail is where waste leaves the body. Use the scalpel or scissors to cut upward along the belly, toward the head. Be very gentle! We don’t want to puncture the organs inside. As the cavity opens, a whole new world is revealed. We can also make an additional cut This will help us with the discovery of the different organs.

🧠Part 3: Discovering the Organs – One by One
Now we use tweezers to explore, gently lifting each organ. We place each one in the tray, and write its name on a label. We tell its story and how it connects to the next.

1. Here are the Intestines 🍝 from latin ntus meaning “inside”.Long, coiled, tube-like. They absorbs nutrients from food and leads to the anus and is attached to the stomach.

2. Stomach 🛢️ from Latin Stomachus meaning “gullet”. A pouch-like organ near the front. If we cut it open we may find even what the fish ate last. His function is like yours, to break down the food. It is connected to the liver and intestines. Stomachus (Latin) = “gullet”.

3. Liver🍷from Hepar (Greek) = “liver” Large reddish-brown organ. His job is to filter blood and produce bile. It is attached to intestines via the small greenish sac which is the 💚 bile sac .He is tied to the liver and opens into the intestines.

4. Once we have gently removed the intestines, stomach, and liver, we can observe what remains in the upper part of the body cavity. Look closely near the spine. Do you see this shiny, silver sac? (It might look like a soft balloon, filled with air.) This is the air bladder or swim bladder. It helps the fish stay at just the right depth in the water—without using its fins.When the fish wants to float higher, it adds gas to this sac. When it wants to sink, it releases some gas. It’s like an inner balloon the fish can control.📍(Invite the children to touch.) Can you feel how soft it is?
   Above the swim bladder and tucked along the spine, we can now spot the next part of our journey: the kidneys. They clean the fish’s blood and help control the water and salt inside the body.Fish live in water all the time, so their kidneys are always working to keep the balance just right. Too much water? They remove it. Not enough salt? They keep it in. 🧐 I wonder… do all fish have the same kind of kidneys, even if they live in saltwater or freshwater?

5. Once we’ve explored the swim bladder and traced the kidneys along the spine, we can shift our attention forward—closer to the head.

   Just behind the gills, tucked low in the body cavity, we discover another small but powerful organ. It may not look like much—but this organ never rests. It is always working.

   It is the Heart ❤️

🧠 Part 4: The Brain – Our Final Discovery
At last, we move to the head. Carefully cut through the top of the skull, above the eyes we can find a small cavity where we find the brain meaning “inside the head” —small and soft. It's function is controls movement, senses, and balance. It directs the whole body.

Do you remember the Great River? It tells us that life flows through all living things. This fish carries different departments in its body. It shows us that each part depended on another. Each part is different and each part has a job.

🧐 I wonder… What would happen if even one of these organs stopped working? How are my organs similar to the fish’s? Do all fish look the same inside? What other animals have swim bladders?

With Montessori joy,
Vanina 😊