Porifera - Sponges

Question 1

What is are sponges skeletons made up of

Answer 1

Collagen - Spongin
Spicules - Calcium carbonate or silica

Question 2

Which is the largest of the 3 classes - Calcerea, Demospongiae or Hexactinellida

Answer 2

Demospongiae

Question 3

What is the scientific name for collar cells and what is their role/placement

Answer 3

Choanocytes
Possess flagellum that generates a water current so the collar can trap food
Choanocyte then ingests food by phagocytosis
Line inner surface of the mesophyl

Question 4

What is the amoebocytes role/placement

Answer 4

Digest food from choanocytes and distribute nutrients
Within the gelatinous mesophyl

Question 5

What is the porocytes role/placement

Answer 5

Pores called ostium allow movement of water in and out of the spongocoel
Span the body wall of the sponge

Question 6

What is the opening of the sponge called

Answer 6

Osculum

Question 7

What is the Pinacocytes role/placement

Answer 7

Epidermal cells for protection

Question 8

Give the 3 body plan types of sponges

Answer 8

Asconoid - Small vase-like structure
Synconoid - Larger with folding in body wall
Leuconoid - Largest with small flagellated chambers

Question 9

Name given for feeding in sponges and outline the process (5)

Answer 9

Filter-feeding
1. Water is drawn through ostia into spongocoel
2. Choanocyte’s flagella draws water through its collar
3. Food particles are engulfed by phagocytosis
4. Food particles are digested in choanocyte or transferred to amoebocytes
5. Water is expelled through osculum by -ve pressure

Question 10

Outline sexual reproduction in sponges (3)

Answer 10

1. Sperm from amoebocytes are released into spongocoel and carried out through the osculum
2. Eggs from choanocytes are fertilised by these sperm from another organism of the same species in the mesophyl
3. The zygote forms into free-swimming larvae which will eventually settle and grow

Question 11

What are the internal buds formed called during asexual reproduction

Answer 11

Gemmules