PHYLUM PORIFERA

Question 1

What are the key traits of the metazoa?

Answer 1

Fully multicellular
Ability to move
Collagen
Heterotrophy (able to consume large-bodied organisms)

Question 2

How is the Phylum Porifera different from the rest of the Metazoans?

Answer 2

Cellular level of organization (no true tissues)
No mouth/gut
No organs/organ system
No circulatory system
No clear axes of symmetry

Question 3

What is the name of the sub-kingdom for the Phylum Porifera?

Answer 3

Parazoa

Question 4

Defining traits of the Phylum Porifera:

Answer 4

1) water canal system

2) mesohyl

Question 5

What are the parts of the water canal system of the Phylum Porifera?

Answer 5

ostia (many incurrent pores)
Oscula (large excurrent pores)
Spongocoel

Question 6

How are the three body plans of the sponges?

Answer 6

Ascon type: single flagellated pumping cavity
Sycon type: many flagellated canals radiate from the spongocoel
Leucon: many flagellated chambers connect by passive canals

Question 7

What are pinacocytes and why are they not considered as true epithelium?

Answer 7

For the pinacoderm. Inner and outer body covering. Not considered as true epithelium because they lack

1) basal lamina
2) intercellular junctions
3) apical-basal polarity
4) ability as a layer to regulate ion levels

Question 8

What are archaeocytes?

Answer 8

Amoeboid cells that can transform into any cell type (totipotent). Special amoebocytes make spicules and spongin fibers (collagen) some may transport food and eggs

Question 9

What are myocytes?

Answer 9

Contractile cells that encircle the oscula and flagellated chambers. Can open and close the oscula in response to the environment stimuli

Question 10

What are choanocytes?

Answer 10

Collar cells. Form the choanocyte layer. Function in pumping and feeding: a ring of microvilli surrounds the flagellum. The flagellum has a vane like the choanoflagellates flagellum.

Question 11

What are porocytes?

Answer 11

A tubular cell. Forms the ostia in some group

Question 12

How does the choanocyte feed?

Answer 12

Phagocytize very tiny particles
Microvilli traps the particles
Pinocytes and amoebocytes may also phagocytize food particle
Some are predatory and hook spicules acts like velcro

Question 13

How do sponges reproduce?

Answer 13

Both asexual (budding and fragmentation) and sexual

Question 14

What are the three classes of Porifera and differentiate them.

Answer 14

Calcarea: has calcareous spicules, no spongin, small
Demospongiae: silica spicules, some have spongin, most successful of the three classes
Hexactinellida: “glass sponges”, mostly found in deep sea. Has an odd “modified leucon” canal system