Chapter 7 Invertebrates

Question 1

radial symmetry

Answer 1

organisms have several ways in which they can be sectioned in half, and still have two equal halves, each being a mirror image of the other.

Question 2

Bilateral Symmetry

Answer 2

There is only one way in which the animal can be divided in half to make two equal halves with each half being a mirror image of the other

Question 3

Asymmetric

Answer 3

In these organisms, there is no way in which it can be divided into two equal halves which are mirror images. They have an irregular shape.

Question 4

Monecious

Answer 4

one individual has both male and female sex organs (“one-house”)

Question 5

Dioecious

Answer 5

two separate sexes. Each individual is either a male or a female (“two houses”)

Question 6

Asexual

Answer 6

new individuals develop without gametes; either by “budding” or by “regeneration.”

Question 7

Oral

Answer 7

mouth end

Question 8

aboral

Answer 8

end opposite of the mouth

Question 9

distal (terminal)

Answer 9

end of appendage opposite to where it is attached.

Question 10

basal (proximal)

Answer 10

end of appendage to where it is attached

Question 11

anterior

Answer 11

front end (i.e. the direction it moves)

Question 12

dorsal

Answer 12

back

Question 13

lateral

Answer 13

side

Question 14

ventral

Answer 14

belly

Question 15

posterior

Answer 15

rear end

Question 16

cross section

Answer 16

cut upon a segmented worm vertically and it is the middle portion.

Question 17

median longitudinal cross section

Answer 17

cut a worm horizontally into long sections

Question 18

Phylum: Cnidaria (polyp - sea anemone, medusa - jellyfish, and coral).

What are the three characteristics?

Answer 18

• gastrovascular cavity
• tentacles
• stinging cells

Question 19

3 Classes of sponges

Answer 19

1. Bath sponge: contain “spongin” which are elastic fibers.
2. Calcareous sponges: contain calcium carbonate making them hard like tiny needles.
3. Glass sponges: contain silica (glass-like) spicules.

Question 20

Phylum: Platyhelminthes

What are the three classes?

Answer 20

1. Free-living (i.e. planarians)
2. Tapeworms - intestinal parasite in humans or other vertebrates.
   - have segments
   - each segment has both female and male sex organs
   - has scolex, suckers, and spines which allows it to attach to the wall of the hosts intestines.
3. Flukes
   - look similar to freeliving flat worms
   - have complex life cycle

Question 21

Phylum: Nematoda (Ascaris, Hookworm, Pinworm)

What are some characteristics?

Answer 21

• contain roundworms
• they have no circulatory system
• they have no hair
• have a flat, non-muscular digestive tract

Question 22

Why do Ascaris produce so many eggs?

Answer 22

Because the life cycle is complex so by producing many eggs it ensures at least 1 will survive.

Question 23

Phylum: Annelida

Answer 23

-bodies composed of many, similar, ring-like segments; thus, they are commonly called the segmented worms.
-usually have hairs, or at least a few short bristles.
-contain a muscular digestive tract
-contain circulatory system with blood
Ex: Earthwords (Class: Oligochaeta), Leeches (Class: Hirudinea).

Question 24

Mollusca

Answer 24

snails; bivalves; chitons; and cephalopods

• soft body and hard shell
• muscular foot and mantle

Question 25

Echinodermata

Answer 25

starfish; sea urchins; brittle stars; sand dollars

-tube feet; spiny skin; pentra-radial symmetry; water-vascular system