Basal animals: Parazoa Phylum Porifera

Question 1

Basal Animals

Answer 1

• Parazoa
• Radiata

Question 2

Parazoa
Phylum Porifera:

Answer 2

Sponges

Question 3

Radiata
Phylum Cnidaria:

Answer 3

Hydroids, jellyfish, sea anemones, corals

Question 4

Radiata
Phylum Ctenophora:

Answer 4

Comb jellies

Question 5

Characteristics of the sponges

Answer 5

• Include freshwater and marine species
• no obvious or consistent body symmetry
• no hox genes
• no body cavity- water flows through sponge body
• cellular plasticity
• choanocytes- “collar cells” with flagellum for pumping water and suspension feeding

Question 6

Choanocytes

Answer 6

pumping water and suspension feeding

Question 7

Choanoflagellates

Answer 7

• protists (unicellular eukaryotes)
• aquatic, mostly marine
• filter feed on bacteria
• most are unicellular, some are “colonial”
• collare of cells processes surrounding flagellum
• once considered animals, now animal precursors

Question 8

Choanoflagellates

Answer 8

• Similar collar cells discover in other animal groups ( cnidaria, flatworm, rotifers, echinoderms), not in multicellular organism (like fungi, plants or microbes)
• analyses nuckear and mitochondrial genes from choanoflagellates and animals- support placement of choanoflagellates as sister group of metazoa
• signaling and adhesion genes preiously known only from metazoa

Question 9

phylum porifera:

Answer 9

• tube sponge pumping water dye through sponge
• simple sponge (asconoid)
• interneduate soinge (syconoid)
• complex sponge (leuconoid)

Question 10

sponge skeletons

Answer 10

• Spicules
• Spongin fibers