Porifera Flashcards
Where in the phylogeny by Brusca et al. are the sponges located?
basal lineage within Metazoa, separate from
Eumetazoa which includes cnidarians and bilaterians.
What are the synapomorphies of sponges? (4)
Aquiferous system
Choanocytes
Lack of true tissues
Composed of spicules
What are the 4 classes of sponges?
Hexactinellida (Glass sponges)
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Demospongiae (Demosponges)
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Homoscleromorpha
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Calcarae
What are the characteristics of Calcarae? (4)
Spicules made of calcium carbonate
Typically small (<10 cm)
All 3 body plans present
Exclusively marine
What are the characteristics of Hexactinellida? (4)
Syncytial tissues (cells share cytoplasm)
Siliceous spicules (six-rayed)
Mostly deep sea, marine
Lack contractile pinacocytes
What are the characteristics of Demospongiae? (4)
Spicules of silica and/or spongin
Leuconoid body plan only
Includes the bathe sponges
Includes most sponge species (80%)
What are the characteristics of Homoscleromorpha? (4)
Spicules absent or siliceous
Distinct basal membrane
Previously classified under Demospongiae but now considered a separate class
Mostly marine, shallow water
How are the 4 sponge classes related? (4)
Calcarea is the most distinct due to its calcareous spicules
Demospongiae and Hexactinellida are more closely related
Homoscleromorpha is now recognized as separate from Demospongiae
Some molecular studies suggest that sponges may
What body plans do sponges exhibit?
Asconoid
Syconoid
Leuconoid
What is an asconoid shape?
Simple tube-like body, small size due to insufficient water flow
What is a syconoid shape?
Folded walls increase surface area for filtration.
What is a leuconoid shape?
Most complex, with multiple flagellated chambers for efficient water
filtration (found in most large sponges).
What are the 6 types of cells found in sponges?
Choanocytes
Pinacocytes
Porocytes
Amoebocytes
Sclerocytes
Spongocytes
What do choanocytes, pinacocytes, and porocytes do>
Choanocytes
Generate water flow, capture food particles
Pinacocytes
Flattened cells forming the sponge;s outer layer
Porocytes
Tubular cells forming ostia (pores)
What do amoebocytes, sclerocytes, and spongocytes do?
Amoebocytes (Archaeocytes)
Mobile, multipurpose cells involved in digestion, transport, and spicule
production.
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Sclerocytes
Produce spicules
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Spongocytes
Produce spongin fibers
How do sponges eat?
Sponges are filter feeders. Choanocytes trap food particles (bacteria, plankton)
and transport them to amoebocytes for digestion.
How do sponges breathe?
No specialized organs; oxygen diffuses from water into cells.
How do sponges expel waste?
Wastes are expelled by diffusion.
How do sponges reproduce?
Sponges reproduce asexually and sexually. Aseually by budding, fragmentation,
or gemmules and sexually most sponges are hermaphroditic, producing sperm and
eggs at different times.
What are the larval stages?
Larval stages: Parenchymella larva (Demospongiae), Amphiblastula larva
(Calcarea)
How do larval sponges live?
Larvae are free swimming before settling to become sessile adults.
What are spicules, and what are they made of?
Spicules are microscopic, rigid structures that serve as the skeletal elements of
sponges.
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Made with Calcium carbonate, silica, spongin
Five types of spicules
Monaxon: needle-like, straight or curved
Triaxon: Y-shaped (three rays)
Tetraxon: Four rays
Hexactine: Six rayed (found in glass sponges)
Polyaxon: Star-like or multi rayed
Function of spicules (4)
Helps sponges maintain their shape
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Sharp spicules deter predators
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Spicules are used to classify sponges
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Contribute to ocean sediments and silicon cycling
