Worm Dissection (Remake) || If You Cut a Worm in Two [EDU]

Summary

This educational video explores the anatomy of an earthworm, a member of the phylum Annelida. It covers the external features like segmented body and setae for movement, and internal structures including the clitellum for egg cocoons. The dissection reveals the brain, nerve cord, five aortic arches for circulation, and reproductive organs. Earthworms lack lungs, breathing through their skin, and their castings enrich soil for plants.

Takeaways

• 🐛 Worms are invertebrate animals with various types including earthworms, roundworms, and flatworms.
• 📐 Earthworms belong to the phylum Annelida, characterized by their segmented bodies.
• 🦿 The setae, or tiny hairs, on the underside of earthworms aid in movement by acting as anchors in the soil.
• 💧 The clitellum on earthworms secretes fluid to form cocoons for their eggs and helps in orienting the worm's anterior and posterior ends.
• 🧠 Earthworms have a small brain with two lobes and a ventral nerve cord running the length of their body.
• 🍽️ The pharynx is the starting point of the earthworm's digestive system, acting as a suction pump for drawing food into the mouth.
• 🌱 Earthworms are hermaphrodites, possessing both male (seminal vesicles) and female (seminal receptacles) reproductive organs.
• ❤️ Earthworms have five aortic arches that function as hearts, pumping oxygenated blood throughout their body.
• 🌿 Earthworms lack lungs; they breathe through their skin, requiring moisture to facilitate gas exchange.
• 💩 Earthworm droppings are rich in nitrogen and other nutrients, making them excellent natural fertilizers for plant growth.
• 🔍 Worms have no eyes, ears, or nose but can detect light, touch, vibrations, and chemicals through their skin and nerve receptors.

Q & A

What is the general term for a large group of invertebrate animals that includes earthworms, roundworms, and flatworms?

The general term for this group of invertebrate animals is 'worm'.

What phylum do earthworms belong to and what does the name of the phylum mean?

Earthworms belong to the phylum Annelida, which means 'ringed' and refers to the series of ringed segments that make up the body of a worm.

What are the tiny hairs on the underside of an earthworm called and what is their function?

The tiny hairs on the underside of an earthworm are called setae, which help the worm move by acting as anchors when the muscles along the worm extend.

What is the function of the clitellum on an earthworm?

The clitellum secretes a viscous fluid that forms a cocoon for the worm's eggs.

How can you determine the anterior and posterior ends of an earthworm?

The part closer to the clitellum is the anterior end (head), and the other end is the posterior end (towards the rear).

What is the purpose of pinning an earthworm during dissection and where should the pins be placed?

Pinning an earthworm during dissection prevents it from moving around. The pins should be placed diagonally across the dissection tray at the head and at the end of the tail.

What is the function of the septum in an earthworm?

The septum are flaps attached to the skin that divide the worm into segments.

What is the role of the earthworm's brain and ventral nerve cord?

The brain is located near the head of the earthworm and has two lobes. The ventral nerve cord runs the length of the body, connecting to the brain and allowing the worm to move and respond to stimuli.

How many hearts do earthworms have and what are they called?

Earthworms have five hearts, known as aortic arches, which are arch-shaped and pump blood throughout the body.

What is the function of the gizzard in an earthworm's digestive system?

The gizzard has a thicker muscle lining and grinds up the food. Since worms don't have teeth, they swallow little bits of rock or sand to help break down the food.

How do earthworms breathe and what is necessary for this process?

Earthworms breathe through their skin, as air dissolves on the mucus of their skin. They must stay moist to breathe; if they dry out, they suffocate.

What is the significance of earthworm droppings for plant growth?

Earthworm droppings are rich in nitrogen and other nutrients beneficial for plant growth, making earthworms a great natural fertilizer for soil.