Metazoa

Question 1

what is the metazoa group?

Answer 1

major division of the kingdom of Animalia , multicellular organisms with cells differentiated into tissues and organs

Question 2

what is the eumztaeoa group

Answer 2

• clade contains all major animal groups- except sponges
• all animals form true tissues (either 2 or three germ layers)
• some formation of nerves and embryos go through gastrulation stage

Question 3

what is the bilateria group

Answer 3

• includes most animal phyla- main characteristic is bilateral symmetry
• triploblastic development- three germ layers ( endoderm, ectoderm and mesoderm)
• most have a digestive tract with two mouth openings- mouth and anus

Question 4

what is the lophotrocozoa group

Answer 4

• no unique characteristics shared by ALL members
• named after lophophore (crown of ciliated tentacles present in some members) and trochophore larva ( present in most molluscs and they are a small circle of cilia shaped like. spinning top)

Question 5

what are the deuterostomes and protostomes groups

Answer 5

Division of Bilateral based on development- 3 factors
- pattern of cleavage
- coelom formation
- blastopore

Question 6

explain deuterostome development

Answer 6

1) radial cleavage- perpendicular cells at 8 cell stage. inderminate- all cells have all genetic info/not specialised
2) coelom formed- folds of the archeninterior forms pouches
3) blastropare fate- becomes anus

Question 7

explain protostome development

Answer 7

1)spiral cleavage- cells rotated. determinate- cells at this stage or determind
2) 2 clumps of esodermal tissue migrate to interior of embryo and cavities develop to form hollow coelom opening
3) biastopare forms into mouth - mouth first

Question 8

what is the ecdysozoa group

Answer 8

• more recently added
• common to all is the fact that they moult
  most successful abundant group
• distinctive feature- exoskeleton