Phylum Porifera

Question 0

What are sponges?

Answer 0

No true tissues
Filter feeders
99% of species are marine
Like clearer waters
Murky waters may clog pores so can’t get nutrition and oxygen
Brightly coloured due to dermal cell pigmentation
Either alone, branched, encrusting, hole-boring

Question 1

Phylum Porifera?

Answer 1

First multicellular animals
Basal members of phylogenetic tree
Organization very distinct from other animals
Placed into diff grade (parazoa)–>beside animals

Question 2

How to classify sponges?

Answer 2

3 classes based on spicules: calcarea, demospongiae, hexactinellida

Question 3

Types of canal systems?

Answer 3

Asconoid, syconoid, leuconoid

Question 4

Asconoid?

Answer 4

Most simple organization
Small and tube shaped members grow in groups attached to stolon
Water through porocytes
Water into flagellated spongocoel

Question 5

Syconoid?

Answer 5

Layer folded back and forth to make radial canals that are lined with choanocytes (flagellated canals).
Water first moves into incurrent canals and then into radio canals via prosopyles
Filtered water goes through apopyles into spongocoel lined with epithelial like cells

Question 6

Leuconoid?

Answer 6

Most complex
Permits increase in sponge size
Form large masses with many oscula
Clusters of flagellated chambers 
No spongocoel

Question 7

Types of sponge cells?

Answer 7

Pinacocytes, porocytes, choanocytes, archaeocytes (amoebocytes)

Question 8

Pinacocytes?

Answer 8

Cells of external epithelium
Cell bodies extend into mesohyl
Somewhat contractile- help regulate surface area
Can be modified as contractile mycocytes that come around the oscula/pores to regulate water flow.

Question 9

Porocytes?

Answer 9

Tubular cells piercing body wall of Asconoid sponges

Permit water flow

Question 10

Choanocytes?

Answer 10

Flagellated cells lining canals/chambers
Flagellum surrounded by collar
The micro villi of these collars act to strain incoming food particles by trapping in secreted mucus.
Slide down to base of cell to perform phagocytosis

Question 11

Archaeocytes?

Answer 11

Ameboid cells moving through mesohyl
Phagocytize particles at epithelium and receive particles for digestion from choanocytes
Can differentiate into any of the other cell types

Question 12

Cell types?

Answer 12

Sclerocytes, spongocytes, collencytes –> skeletal components

Question 13

Sclerocytes?

Answer 13

Secrete mucus

Question 14

Spongocytes?

Answer 14

Secrete spongin fibres

Question 15

Collencytes?

Answer 15

Secrete fibrillar collagen

Question 16

Sponge skeletons?

Answer 16

Skeletons give structural support

Prevent collapse of canals and chambers

Question 17

What are sponge skeletons composed of?

Answer 17

Collagen fibrils occur throughout intercellular matrix (members of class demospongiae secrete spongiae)
Spicules add additional support
Siliceous–> demospongiae and hexactinellida
Calcium carbonate–> calcarea

Question 18

Feeding of sponges?

Answer 18

All filter feeders
Phagocytosis of suspended particles
Inter acellular digestion (archaeocytes)

Question 19

Respiration and osmoregulation?

Answer 19

No respiratory or excretory organs
All done through diffusion
Contractile vacuoles in archeocytes and choanocytes of freshwater sponges

Question 20

Locomotion?

Answer 20

Some capable of crawling behavior

Question 21

Sponge reproduction?

Answer 21

All capable of both asexual and sexual reproduction

Question 22

Asexual?

Answer 22

Usually by fragmentation or external budding
Some form internal buds (gemmules)
Dormant masses of encapsulated archaeocytes (formed during unfavourable conditions)

Question 23

Sexual?

Answer 23

Most are monoecious (both male and female sex cells found in individual)
Sperm and oocytes develop from transformed choanocytes or archaeocytes (sperm released into water and taken up by canal system to be carried through mesohyl by carrier cells)
Can be oviparous (release both oocytes and sperm)

Adult sponges stationary but zygotes motile 
Ciliates larva (parenchymula) swim to new location

Question 24

Types of sponges?

Answer 24

Class calcarea, hexactinellida, demospongiae

Question 25

Class calcarea?

Answer 25

Chalk sponges
Spicules composed of calcium carbonate, all 3 canal systems possible
Often small sponges

Question 26

Class hexactinellida?

Answer 26

Glass sponges
Skeleton made of 6 rayed siliceous spicules
Body made of single continuous syncytial tissue-trabecular reticulum
Bilayered into primary and secondary reticulum containing cellular elements but also choanablasts?
Nearly all deep sea

Question 27

Class demospongiae?

Answer 27

Skeleton made of siliceous spicules and/or spongin
Only leuconoid canal system
80% of all sponge species
Larger sponges