Invertebrates (Marine) (E1)

Question 1

Sponges

Answer 1

• Eukarya, Animalia, Porifera, asymmetrical, acoelomates, hermaphrodites, sessile
• Lack tissues (no germ layers)
• Filter feed by choanocytes eat by phagocytosis, amoebocytes use pseudopodia to digest and carry nutrients through the sponge
• Make both sperm and eggs, releasing into water

Question 2

Cnidarians

Answer 2

• radial symmetry, no brains, hydrostatic skeleton
• Polyps are cylindrical forms fixed to a substrate
• Medusa is a flat mouth-down version of the polyp, moves by contraction
• Both use tentacles in a ring around the mouth to eat
• The gastrovascular cavity acts as a hydrostatic skeleton (mouth closes, contraction causes the animal to change shape)

Question 3

Medusozoan

Answer 3

• all cnidarians produce a medusa part of this clade
  Ex. Jellyfish (scyphozoan), box jellyfish (cubozoan), hydrozoans

Question 4

Anthozoans

Answer 4

Ex. sea anemones and corals
Occur only as polyps, and have an exoskeleton