Annelida Questions

Question 1

What is the concentration of nervous tissue in the head end of an organism called?

Answer 1

This concentration is known as cephalization.

Question 2

What is a group of nerve cells called?

Answer 2

“Ganglia” refers to a group of nerve cells.

Question 3

What is an organism that has both male and female sex organs called?

Answer 3

A hermaphrodite.

Question 4

Name the 3 classes that make up the phylum Annelida and give an example.

Answer 4

Phylum Annelida consists of the classes Oligochaeta (earthworms), Hirudinea (leeches)
and Polychaeta (marine worms).

Question 5

Name of the body cavity found in earthworms.

Answer 5

Earthworms possess a true coelom as they are coelomates.

Question 6

what does an earthworm need to reproduce.

Answer 6

For respiration to take place the earthworm must be moist.

Question 7

What is the function of nephridia?

Answer 7

Nephridia are excretory structures similar to kidneys. They filter/remove cellular
metabolic wastes from the organism’s blood.

Question 8

What is the function of the clitellum?

Answer 8

The clitellum is the band of thickened segments on the earthworm. The clitellum
produce a ball of mucus into which the eggs and sperm are released .

Question 9

Give three agricultural benefits of the earthworm.

Answer 9

Three agricultural benefits earthworms possess are they act as natural composers which
transform dead organic matter into fertile soil, cycle nutrients through the soil, and keep
the soil structure open helping drainage.

Question 10

What does a leech release during a feeding? Why?

Answer 10

During feeding leeches release an anti-clotting enzyme into the blood prevents and even
dissolves blood clots. This allows for the continuous flow of blood from host to leech and
prevents the blood from clotting in the leech’s stomach.

Question 11

Where are the suckers of a leech located? What are the functions of each?

Answer 11

At each end of a leech are powerful suckers. The posterior sucker is used to anchor/attach to the host while the anterior sucker is used to feed and suck up blood.

Question 12

How is the nematode’s circulatory system different from an earthworm?

Answer 12

Annelids have a complete circulatory system, while nematodes don’t have a circulatory
system.

Question 13

Describe the structures involved with an earthworm’s movement.

Answer 13

Earthworms move by using longitudinal muscles along their body to move. When these
muscles contract the worm shortens and vice versa. This alternate contraction movement allow
worms to move through a wiggling motion

Question 14

Compare and contrast the body cavities (coelom) of the 3 worms Phyla
(flatworms, roundworms, and segmented worms)

Answer 14

Segmented worms (Annelida) have a true coelom with lining, flatworms
(Platyhelminthes) have no coelom, and roundworms (Nematode) have a false coelom known as
a pseudocolor.

Question 15

Name the structures of the circulatory system. Describe the pathway of blood circulation
throughout the earthworm.

Answer 15

1) Dorsal blood vessel - Carry blood to the front of the body
2) Aortic arches (Hearts) - 5 hearts pump blood into blood vessels; these structures connect
both dorsal and ventral blood vessels
*not numbered - Ventral blood vessel – Carries blood in the posterior direction

Question 16

List 4 characteristics of the Nematoda phylum.

Answer 16

Members of Phylum Nematoda are pseudocoelomates, they possess a ONE WAY
digestive tube with a mouth and an anus. They do not possess true respiratory or
circulatory systems. Strictly sexual reproduction with separate sexes (male and
female). Roundworms also exhibit cephalization with several ganglia!

Question 17

Compare and contrast the digestive system of Nematoda to Platyhelminthes.

Answer 17

Platyhelminthes have an incomplete digestive system (two-way). As in food enters
and leaves the same opening. Flatworms possess a gastrovascular cavity. Nematodes have a complete one way digestive system with two openings.

Question 18

In what ways are nematodes beneficial to the environment?

Answer 18

Nematodes are decomposers that recycle bacteria, fungi, and decaying organic matter
back into the soil. This is important for energy production and the recycling of
nutrients.

Question 19

What are the major differences in structure between flatworms and roundworms?

Answer 19

Major differences between flatworm and roundworm structures are:
Flatworms are acoelomates, roundworms are pseudocoelomates.
Flatworms have one opening (two-way digestive system).
Roundworms have two openings (one-way digestive system).
Flatworms are hermaphrodites where as Roundworms have separate
sexes.

Question 20

list 4 characteristics of the nematoda phylum

Answer 20

They are free-living organisms.
They reproduce sexually. …
They have a nervous system.
They are parasites of both plants and animals.

Question 21

compare and contrast the digestive system of nematodes to Platyhelminthes

Answer 21

Platyhelminthes have an incomplete gut whereas nematodes have a complete one.

Question 22

in what ways are nematodes beneficial to the environment

Answer 22

regulate the populations of other soil organisms

Question 23

what are the major differences in structure between flatworms and roundworms

Answer 23

A flatworm has a thin, dorsoventrally flattened body. Roundworms are more cylindrical in shape and tapered to a fine point at one end.