Porifera Flashcards
1
Q
introduction
6 points
A
- isolated phylum
- multicellular
- sessile
- ancient lineage (appeared 540mya)
- benthic
- all depths
2
Q
classification
A
kingdom: metazoa (multicellular)
phylum: porifera
Class:
Calcarea
Hexactinellida
Demospogiae
3
Q
Key characteristics
7 points
A
- metazoa - without true tissues or organs
- asymmetrical
- totipotent cells (give rise to any cell type)
- body formed of monolayer of cells surrounding a secreted matrix
- choanocytes driving aquiferous system???
- adults sessile filter feeders
- larval stages motile and lecithotrophic
4
Q
Body structure
Outer surface
A
- (pinacoderm) made up of pinacocytes
- can be simple externam sheet with ostia
- not present in hexactinellida (thin dermal layer)
5
Q
Body structure
inner surface
A
- (choanoderm) made of choanocytes
2. simple and continuous or folded and subdivided
6
Q
body structure
separation of inner and outer surface
A
separated by mesohyl (made of mesenchyme)
varies in thickness
vital roles
7
Q
body structure
aquiferous system
A
- brings water into sponge
- water pulled in via ostia
- driven across choanoderm by beating of choanocyte flagella
- choanocytes pump large volumes of water through body at low pressures = water current
- water flows close to cells responsible for food gathering and gas exchange
- excretory and fdigestive wastes and reproductive products expelled via osculum
8
Q
morphological diversity
A
- Asconoid - simple and continuous choanoderm
- syconoid - simple folding of pinacoderm and choanoderm
- Leuconoid - folding and subdivision of choanoderm
9
Q
Feeding
A
- filter feeders
- aquiferous system
- size selective particle feeders - series of sieves of decreasing mesh size 5-50um down to 2-5 um
- intracellular digestion
- archaeocytes transport nutrients throughout mesonchyme
10
Q
Reproduction
Sexual
A
- Hermaphrodites (produce eggs and sperm different times)
- produced by choanocytes and released via aquiferous system
- oviparous and viviparous species
- larval ecology split by habitat (littoral/subtidal)
11
Q
Reporduction
Asexual
A
- fragmentation
- budding
- asexual larvae
12
Q
Class hexactinellida
A
- glass sponges
2. spicules 6-rayed (hexactinal) and siliceous
13
Q
class demospongiae
A
- 95% living species
2. spicules siliceous but not hexactinal
14
Q
class calcarea
A
- calcareous sponges (shallow)
2. rayed spicules (1,3,4) composed of calcium carbonate
15
Q
distribution
calcareous and coralline demosponges
A
- abundant in shallow water (less than 200m)
2. need firm substrate
