BIOL 2003 Lecture Notes - Lecture 4: Choanocyte, Osculum, Calcium Carbonate
Phyla, Porifera and Placozoa
September 18, 2015
Phylum Porifera:
• What are Sponges?
o Sac-like bodies perforated by many pores
o Sessile filter feeders
o Use flagellated collar cells (choanocyte) to move water
▪ Body is efficient aquatic filter (aquiferous
system)
o ~5-8,000 species of sponge (mostly marine)
• The Aquiferous System:
o For every 1cm3 of sponge filters 20L of
water per day
• The Choanocyte
o Flagellated collar cell
o THE cell of the sponge
o Interestingly, very similar to the protist
o Help create current of water
• Canal Systems
o Asconoid (choanocyte-lined spongocoel)
▪ Simplest and smallest
▪ Only in class Calcarea
o Synconoid (choanocyte-lined canals)
▪ Still relatively small and tubular
▪ Folder inner layer creates canals
▪ Also only seen in class Calcarea
o Leuconoid (choanocyte-lined chambers)
▪ Increase in size
▪ No spongocoel (just osculum)
▪ In all classes
• What makes a sponge, a sponge?
o Choanocytes – water currents and feeding
o Archaeocytes – totipotent amoeboid cells in meohyl
▪ Can become cells that…
• Phagocytosize (injest)
• Make spicules
• Make sponging
• Make collagen
• Are used for reproduction
• Sponge skeletons
o Collagen fibres in all sponges
▪ Some have specific collagen fibres called sponging
o Siliceous spicules (silia) aka glass in some sponges
o Calcium carbonate can also be present
o Used to deter predators (spicules)
Incurrent
pores
(Ostia)
Excurrent
pores
(Oscula)
Spongocoel
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Incurrent pores (ostia: flagellated collar cell, the cell of the sponge. Interestingly, very similar to the protist: help create current of water, canal systems, asconoid (choanocyte-lined spongocoel) Simplest and smallest: only in class calcarea, synconoid (choanocyte-lined canals) Folder inner layer creates canals: also only seen in class calcarea, leuconoid (choanocyte-lined chambers) In all classes: choanocytes water currents and feeding, archaeocytes totipotent amoeboid cells in meohyl, can become cells that , phagocytosize (injest, make spicules, make sponging, make collagen, are used for reproduction. Sponge (cid:498)skeletons(cid:499: collagen fibres in all sponges. Some have specific collagen fibres called sponging: siliceous spicules (silia) aka glass in some sponges, calcium carbonate can also be present, used to deter predators (spicules) Class calcarea: calcareous sponge (calcium carbonate spicules, the only class with all three canal systems, usually small. Class hexactinellida: 6-ray silica spicules (glass lattice) Spicules are non-distinct: used to be within demospongiae, cellular distinctions (pinacoderm is formed completely different from epithelium, distinct skin.
