Phylum Porifera Flashcards
What are sponges?
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
Phylum Porifera?
First multicellular animals
Basal members of phylogenetic tree
Organization very distinct from other animals
Placed into diff grade (parazoa)–>beside animals
How to classify sponges?
3 classes based on spicules: calcarea, demospongiae, hexactinellida
Types of canal systems?
Asconoid, syconoid, leuconoid
Asconoid?
Most simple organization
Small and tube shaped members grow in groups attached to stolon
Water through porocytes
Water into flagellated spongocoel
Syconoid?
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
Leuconoid?
Most complex Permits increase in sponge size Form large masses with many oscula Clusters of flagellated chambers No spongocoel
Types of sponge cells?
Pinacocytes, porocytes, choanocytes, archaeocytes (amoebocytes)
Pinacocytes?
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.
Porocytes?
Tubular cells piercing body wall of Asconoid sponges
Permit water flow
Choanocytes?
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
Archaeocytes?
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
Cell types?
Sclerocytes, spongocytes, collencytes –> skeletal components
Sclerocytes?
Secrete mucus
Spongocytes?
Secrete spongin fibres
Collencytes?
Secrete fibrillar collagen
Sponge skeletons?
Skeletons give structural support
Prevent collapse of canals and chambers
What are sponge skeletons composed of?
Collagen fibrils occur throughout intercellular matrix (members of class demospongiae secrete spongiae)
Spicules add additional support
Siliceous–> demospongiae and hexactinellida
Calcium carbonate–> calcarea
Feeding of sponges?
All filter feeders
Phagocytosis of suspended particles
Inter acellular digestion (archaeocytes)
Respiration and osmoregulation?
No respiratory or excretory organs
All done through diffusion
Contractile vacuoles in archeocytes and choanocytes of freshwater sponges
Locomotion?
Some capable of crawling behavior
Sponge reproduction?
All capable of both asexual and sexual reproduction
Asexual?
Usually by fragmentation or external budding
Some form internal buds (gemmules)
Dormant masses of encapsulated archaeocytes (formed during unfavourable conditions)
Sexual?
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
