Phylum Cnidaria

Question 1

What are the key features of Cnidaria?

Answer 1

• Radial Symmetry - no distinct head, diffuse nerve net
• Two tissue layers: Ecto- and Endoderm with mesoglea in between
• Nematocysts: stinging organelles
• Body plan: sac + tentacles - “stomach” called gastrovascular cavity
• Many are colonial

Question 2

What are the two main body plans seen in Cnidaria?

Answer 2

• Polyps