Invertebrate evo

Question 1

What are the two forms of Cnidaria, what are their key characteristics? Give an example

Answer 1

1. Polyp
   - form of sessile organisms
   - has opening on top
   eg. coral, anemones
2. Medusa
   - form of mobile organisms
   - has opening on bottom
   eg. jellyfish

Question 2

Which invertebrate phylum has radial symmetry and diploblastic tissue?

Answer 2

Cnidaria

Question 3

In which phylum do we see the beginning of a nerve net?

Answer 3

Cnidaria

Question 4

Which invertebrate phylum is an acoelomate?

Answer 4

Platyhelminthes

Question 5

What is the ancestral colonial flagellate that gave rise to invertebrates?

Answer 5

Metazoa

Question 6

In which phylum of invertebrate do we begin to see the development of muscle tissue?

Answer 6

Platyhelminthes

Question 7

Which phylum of invertebrate has a mantle? What is a mantle, and do all the species in the phylum have a mantle?

Answer 7

Mollusca.
A mantle is a water-filled cavity that secretes calcium carbonate which creates shells.
Not all mollusca have a shell, but all mollusca have a mantle.

Question 8

What are the 3 parts of a Mollusca body plan?

Answer 8

1. muscular foot
2. visceral mass (contains the organs)
3. mantle (secretes calcium carbonate)

Question 9

In which phylum do we start to see a closed circulatory system?

Answer 9

Annelida

Question 10

Which phylum are important decomposers?

Answer 10

Annelida

Question 11

What are the three worm phylums, how are they different, how are they similar?

Answer 11

1. Platyhelminthes
   -acoleomates (incomplete digestive tract)
   -no circulatory system
2. Annelida
   -coelmates (complete digestive tract)
   -yes circulatory system
   -fused segmented rings
3. Nematoda
   -psuedocoleomates (complete digestive tract)
   -no circulatory system
   -tough outer cuticle
   Similar: all are protostomes
   all have bilateral symmetry
   all are triploblastic

Question 12

Which phylum has a parasitic relationship with plants and animals?

Answer 12

Nematoda

Question 13

Which invertebrate phylum is the most successful phylum?

Answer 13

Arthropoda

Question 14

What kind of skeleton do arthropods have, what is it made of?

Answer 14

Exoskeleton, chitin

Question 15

What are the 3 major reasons arthopods have done so well?

Answer 15

1. Rigid exoskeleton
   - protection
   - relatively impenetrable by water
   - provides points of attachment for the muscles
2. 2+ pairs of jointed appendages
   - specialized functions: eating, mating, defense etc
3. Segmented bodies
   - well developed anterior sense organs
   - division of labour among segments

Question 16

Which invertebrate phylum are psuedocoelomates?

Answer 16

Nemotoda

Question 17

Which invertebrate phylum are dueterostomes?

Answer 17

Echinodermata

Question 18

What kind of skeleton do Echinodermatas have?

Answer 18

endoskeleton, covered by thin epidermis

Question 19

What kind of symmetry do echinodermatas have; does it look this way?

Answer 19

Bilateral. It doesn’t look this way because most adults have radial symmetry, but as larvae they have bilateral symmetry.