Mrs. Vu's Class Dissections

Perch, Earthworm, Arthropods

The Earthworm, Dissected

The earthworm, or Lumbricus terrestris is a primary consumer, living in mainly warm and wet climates, they eat leaves, grass, and dirt. mostly birds feed on worms when they are abundant, usually in the springtime. A worm's job is to recycle, fertilize, and mix up the dirt. They have the ability to self-reproduce and do not have eyes or formal lungs.

Objectives- discover the internal and external anatomy of the anterior end of the earthworm.

Digestive System- a worm's digestive track is relatively basic. After the food (ex. Soil) is eaten (through the mouth), it gets moved on down the esophagus to the crop, then through the gizzard and past an intestine. At this time the now digested food has been broken down and all usable nutrients have been taken out of the food and what's left is waste. The waste travels down the length of the earthworm until it reaches the anus where it is excreted and mixes with already existing soil. Wastes excreted from the earthworm are filled with new nutrients to fertilize the soil.

Earthworms Are Important!

  • There are about 2,700 different kinds of earthworm
  • There can be over 1 million earthworms in a single acre of land
  • Earthworms secrete a slime that has nitrogen in it, the nitrogen is sticky and forms clumps of dirt
  • Worms are cold-blooded
  • Worms are not born live, they hatch

Worms in the News?

In Guinea, river blindness and worm disease are part of the 17 tropical diseases that the World Health Organization wants to stress and bring more importance to. Guinea is currently attempting to eradicate the worms and inform their people of the potential dangers of these animals and to find a way to be in contact with a healthcare professional.

Perch, An Aquatic Dissection

The Perch

Perch, or Perca flavescens, are dominantly freshwater fish and live in areas such as the Atlantic coast, southern Hudson bay, and on the northern half of the Mississippi drainage. Perch have no eyelids and have five types of fins. Perch, like many aquatic animals, have a special organ called a swim bladder. A swim bladder is an enclosed pocket of air above the gizzard and below the kidney. The swim bladder aids the fish in suspending in water and swimming. On their external, fish have a hard flap called the operculum, this flap is designed to protect the gills from damage.

Objectives-examine a perch's external and internal anatomy, define the organs, define the fins.

Circulatory system- Perch have a closed circulatory system with a two-chambered heart, this heart is separated into two parts: Atrium and Ventricle. The Atrium's job is to collect the blood and bring it to the ventricle, the Ventricle's job is to pump the blood through the body. The blood travels on a loop; deoxygenated blood is taken to be oxygenated by the gills, from the gills the oxygen-rich blood is sent on it's loop through the body, after that the now oxygen-depleted blood is sent back to the heart to be pumped through the loop again.

Did You Know?

  • perch feed on insect larvae
  • female perch mature between ages 2 and 3
  • females can produce between 5,000 and 109,000 eggs in their lifetime
  • yellow perch can live up to 13 years
  • the largest recorded perch weighed 3 lbs and 5 oz.

Various Arthropods

Crayfish and Grasshoppers

Grasshoppers and Crayfish (Crawfish) come from phylum Arthropoda but are reserved to separate classes. Crayfish are both terrestrial and aquatic, grasshoppers are terrestrial. Crawfish feed on dead insects, worms, and leftovers on the bottom of rivers and lakes, grasshoppers eat grasses. Crayfish are found in rivers and brooks that do not freeze over in the cold weather, while grasshoppers live in almost all climates that provide food for them.

Objectives-examine the exoskeleton and similarities between the grasshopper and crayfish

Exoskeleton-the arthropod exoskeleton is a tough outer shell, the exoskeleton is segmented, there are three regions: head, body, tail. The shell is made to protect the internal organs and give shape to the animal. Because of the exoskeleton, arthropods do not have bones.

Want to Know More?

Crayfish

  • can be called crawdad or crawfish
  • have similar family genes to that of the lobster
  • eyes have the ability to wander and perceive a large visual spectrum
  • crayfish tend to feed at night
  • they use their tentacles to smell food
Grasshoppers

  • make music by rubbing legs together
  • can jump 20x their body length
  • over 18,000 species
  • three stages of development: egg, nymph, adult
  • life span is about 1 year