Earthworm Dissection Lab

By:Arlenn Maldonado PAP Guzman Biology P.7

Backround Information of my pink-ish buddy

The reddish-gray-colored common earthworm,is often called a night crawler in the United States, . They are indigenous to Europe, but are now abundant in North America and western Asia.

Typically only a few inches (7 or 8 centimeters) in length, some members of this species have been known to grow to a serpentine 14 inches (35 centimeters). Earthworms’ bodies are made up of ring-like segments called annuli. These segments are covered in setae, or small bristles, which the worm uses to move and burrow.

Night crawlers are so named because they are usually seen feeding above ground at night. They burrow during the day—typically keeping close to the surface—capable of digging down as deep as 6.5 feet (2 meters).

The worm’s first segment contains its mouth. As they burrow, they consume soil, extracting nutrients from decomposing organic matter like leaves and roots. Earthworms are vital to soil health because they transport nutrients and minerals from below to the surface via their waste, and their tunnels aerate the ground. An earthworm can eat up to one third its body weight in a day.

Night crawlers also mate on the surface. . Following mating, each worm forms a tiny, lemon-shaped cocoon out of a liquid secreted from its clitellum, the familiar-looking bulge seen near the first third of the earthworm’s body. The sperm and egg cells are deposited inside the cocoon, and it is buried. After a two- to four-week gestation period, the baby worms emerge.

Earthworms are a source of food for numerous animals, like birds, rats, and toads, and are frequently used in residential composting and as bait in commercial and recreational fishing. Their numbers are strong throughout their range—they’re even considered agricultural pests in some areas—and they have no special status.

Fun Facts

A worm has no arms, legs or eyes.

• There are approximately 2,700 different kinds of earthworms.

• Worms live where there is food, moisture, oxygen and a favorable temperature. If they don’t have these things, they go somewhere else.

• In one acre of land, there can be more than a million earthworms.

• The largest earthworm ever found was in South Africa and measured 22 feet from its nose to the tip of its tail.

• Charles Darwin spent 39 years studying earthworms more than 100 years ago.

• Worms are cold-blooded animals.

• Baby worms are not born. They hatch from cocoons smaller than a grain of rice.

• The Australian Gippsland Earthworm grows to 12 feet long and can weigh 1-1/2 pounds.

• If a worm's skin dries out, it will die.

The squiggly's Digestive system

The digestive system is partitioned into many regions, each with a certain function. The digestive system consists of the pharynx, the esophagus, the crop, the intestine and the gizzard. Food such as soil enters the earthworm’s mouth where it is swallowed by the pharynx. Then the soil passes through the esophagus, which has calciferous glands that release calcium carbonate to rid the earthworm’s body of excess calcium. After it passes through the esophagus, the food moves into the crop where it is stored and then eventually moves into the gizzard. The gizzard uses stones that the earthworm eats to grind the food completely. The food moves into the intestines as gland cells in the intestine release fluids to aid in the digestive process. The intestinal wall contains blood vessels where the digested food is absorbed and transported to the rest of the body.

Objectives

I will learn about the external and internal anatomy of an earthworm.I will also focus on the organs, structures, and functions of the digestive system.