Introduction to invertebrates

Question 1

What is Homology

Answer 1

• shared ancestor

Question 2

What is anology

Answer 2

• convergent evolution (morphological similarity, different tissues)

Question 3

What was the starting point

Answer 3

• Protozoan ancestor
• An archaea engulfed an eubacterium for food

Question 4

List the characteristics
sponges (phylum Cnidaria)

Answer 4

• Simple open body plan
• No true tissue or organs
• Acelomate
• Multicellular
• Suspension feeders
• Gelatinous noncellular mesophyll sandwiched between layers
• Cells can move between layers
• diploplastic - true tissue
• radial symmetry
• gas exchange (diffusion)
• body forms (medusa and polyp)
• Phopalia - statocyst ( sense of gravity and light)

Question 5

What are the 2 phylum Porifera cell types?

Answer 5

• chanocytes
• amebocytes

Question 6

What are the 3 main differences between Phylum Porifera and Phylum Cnidaria?

Answer 6

• Porifera
• no nervous system
• No true tissue
• no symmetry
• Cnidaria
• radial symmetry
• 2-layer tissue (diploblastic)
• simple nervous system

Question 7

What are the 3 body cavities?

Answer 7

• none
• diploblastic (2)
• troploblastic (3)

Question 8

What are the 3 body cavities

Answer 8

• acoelomate (no true body cavity)
• coelom (true body cavity)
• pseudocoelomate (between the body cavity and no body cavity)

Question 9

What are the 3 types of symatry

Answer 9

• none
• bilateral
• radial

Question 9

What is the coelom cavity in a worm good for

Answer 9

• hydroskeleton (fluid or air-filled)
• supports muscles to pull against
• supports the digestive tract
• transports food and waste
• storage of gametes during maturation