Invertebrates: hydra, earthworm and seastar

Question 1

What is a blastula? How is it formed

Answer 1

a blastula is a hollow ball of cells

formed when a zygote mytotically divides without cell growth, then rearranges themselves to form the blastula

Question 2

What is an an antecheron? What is a blastopore?

Answer 2

An antecheron is a hollow tube formed when a region of the blastula moves towards the sphere’s cavity (blastocoel)

a blastopore is the opening to the exterior

Question 3

What does the blastopore develop into?

Answer 3

the mouth and the anus

Question 4

dipoblastic vs tripoblastic

Answer 4

dipo has the two germ
layers ecto and endoderm

tripo has a mesoderm lying in between the ecgo and endoderm

Question 5

what does the endoderm give rise to?

Answer 5

lining of digestive tract

some phyla- lungs and digestive organs (liver and pancreas)

Question 6

what does the mesoderm give rise to?

Answer 6

notochord, the lining of the body cavity (coelom), skeleton (bone or cartilage), muscles, kidneys, gonads and circulatory system.

Question 7

what is the defining feature of cnidaria?

Answer 7

having cnidocytes which are a specialized type of cell used for protection or for immobilizing prey

Question 8

body plan of freshwater hydras (polyp form)

Answer 8

cylindrical column (body), with a sticky basal (pedal) disc at the aboral end and a mouth at the opposite (oral) end. Tentacles extend from low mount of cells by the mouth, the hyptosome