Cnidaria

Question 1

What are the defining characteristics of a cnidarian?

Answer 1

1. Have stinging cells called cnidocytes.
2. diploblastic.
3. Tissue-level organization-muscular and nervous tissue.
4. Radial Symmetry
5. Incomplete gut
6. Extracellular digestion in gastrovascular cavity followed by intracellular digestion.
7. Polymorphism with a polyp (sessile) and medusa (free-swimming) stage.
8. Dioecious. Both asexual and sexual reproduction.
9. Mostly marine, some freshwater

Question 2

What are the advancements shown by cnidarians over sponges. Can you associate these advancements in structure with functions?

Answer 2

1. Presence of an extracell
2. Able to catch own food (gastrovascular cavity) rather than just filter feeding
3. Contain actual tissues instead of just a loose combination of cells (diploblastic), complete with muscular and nervous tissue

Question 3

Polyp vs. Medusa

Answer 3

Polyps are sessile and attached to various formations,
medusa are free-floating.
Polyps tend to be asexual
medusa tend to be sexual.

Question 4

What are coral? Why do you find them only in the tropics? What’s coral bleaching?

Answer 4

It is an anthozoan cniderian. Unicellular protists and algae, which live within the corals in a mutualistic relationship, need light for photosynthesis, limiting reefs to shallow waters of the tropics.

Coral bleaching is when algae dies and leaves whites spots.