M14 Porifera

Question 1

Phylum Porifera

Answer 1

4.69% of Kingdom Animalia. 23,000 species.
-Oldest, simplest and most primitive of all metazoans
-Sessile apart from the tiny filter-feeding flagella located inside them, unable to move (and larvae)
-Can be 100s years old, grow to over 3.5m long.

Question 2

Sponges

Answer 2

Cellular (no tissues or organs). Cell layers are separated by mesohyl, most are unsymmetrical
-Bag, open one end, osculum, closed the other end
-Filter feeders mainly, choanocytes (unique cell type to sponges)
-Marine/ freshwater
-Asexual budding, sexual reproduction to produce larvae.

Question 3

Spicules and cell types (no tissue)

Answer 3

-Pinacocytes = plate like cells, forms outer pinacoderm.
-Choanocytes = flagellated for feeding, forms the choanoderm.
-Porocytes = pore cells, allows water into spongocoel.
-Amebocytes = transport nutrients between cells.
-Mesohyl layer = elastic matrix of collagen and fibres.
-Skeletal elements = spicules made by sclerocytes, spongin made by spongocytes
-Oocytes = egg cells for sexual repro.

Question 4

Feeding

Answer 4

-Sea water is pumped into the sponge through small inhalant openings (ostia) by the beating of flagellated choanocyte cells
-The choanocytes capture food particles from seawater, including bacteria, unicellular algae and even viruses
-From the choanocyte chambers, they are then transferred to the inner Mesohyl layer.

Question 5

Spicules (skeleton)

Answer 5

-Two categories (by size); megascleres (we can see them) and microscleres (microscopic).
-Can be calcareous, siliceous, or made of a type of collagen called spongin.
-Can be hybrid, or made literally only of spicules.

Question 6

Body plan

Answer 6

Asconoid = simple tube with pores, collar cells in spongocoel.

Syconoid = body wall is thick, pores are longer forming canals, collar cells line the canals.

Leuconoid = most complex, masses of tissue with numerous canals, result in chambers lined with collar cells.

Question 7

Systematics (Porifera classes)

Answer 7

Calcarean (calcareous sponges: made of calcite/argonite, spicules are 2-4 pointes, with high diversity. Body plan includes all the types, tend to be in shallow waters, intertidal).

Homoscleromorpha (encrusting sponges: spicules like Demospongiae, lower layer deposition of calcite/aragonite, Leuconoid only, associated with coral or hard surfaces, encrusting. Two families are Oscarelllidae and Plakinidae).

Demospongiae (demosponges: most diverse species, spicules made of collagen/spongin, silicon dioxide. Leuconoid predominantly, marine + freshwater, complex carnivorous forms, symbiosis with algae/bacteria. E.g., breadcrumb sponge, harp sponge is carnivorous).

Hexactinellida (glass sponges: spicules of silicon dioxide, 6 pointed (fused), gelatinous/protein layer inside. Syconoid and Leuconoid, mostly deepwater, reef and non-reef forming).
E.g., Venus flower basket sponge, where it grows a glass house for shrimp couples to live and breed in.

Question 8

Medical industry

Answer 8

-Rich in bioactive compounds, first medicinal drugs were isolated from sponges.
-Symbiotic communities to make bioactive compounds
-Used for anti-oxidant and anti-aging applications
-Still need to standardise processes and evaluate safety.