ch. 33 parazoa

Question 1

invertebrates

Answer 1

animals that lack a backbone
- comprise more than 95% of known animal species

Question 2

phylum of subkingdom parazoa

Answer 2

phylum porifera (sponges)

Question 3

phylum porifera characteristics

Answer 3

• sponges
• lack tissues
• multicellular w/ several types of cells
• no symmetry
• adults sessile, larvae free swimming

Question 4

how do sponges feed

Answer 4

filter feeds - capture food particles suspended in water that passes through their body

Question 5

process of filter feeding in sponges

Answer 5

water drawn in through pores into cavity called spongocoel and out through opening called osculum

Question 6

ostium

Answer 6

opening into a vessel or body cavity

Question 7

osculum

Answer 7

main opening at aboral end of sponge
- Latin origin - mouth

Question 8

porocytes

Answer 8

cells that create openings in the sponge

Question 9

different types of cells in sponges

Answer 9

• choanocytes
• amoebocytes

Question 10

choanocytes in sponges

Answer 10

flagellated collar cells that generate a water current through the sponge to ingest suspended food

Question 11

layer between cell layers in sponge

Answer 11

gelatinous noncellular mesohyl layer

Question 12

amoebocytes in sponges

Answer 12

totipotent stem cells found in mesohyl that aid in digestion and manufacture of skeletal fibers
- absorb food from choanocytes, digest it, and carry to other cells
- move by pseudopodia in mesohyl

Question 13

choano

Answer 13

funnel

Question 14

spicules

Answer 14

structural support; mesohyle

Question 15

reproduction of sponges

Answer 15

sexual and asexual

Question 16

sexual reproduction of sponges

Answer 16

• hermaphrodites (first one sex then other) producing eggs and sperm
• fertilization occurs in mesohyle
• larvae exits through osculum

Question 17

where are gametes derived from in sponges

Answer 17

amoebocytes or choanocytes

Question 18

asexual reproduction of sponges

Answer 18

fragmentation - small fragment/bud may detach and form new sponge