Krausz Marine Biology
Ch. 7: Marine Animals without a Backbone
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General Characteristics:
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Kingdom Animalia
Heterotrophic- cannot make own food
97% of all animal species are invertebrates
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7.1 Sponges
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Phylum- Poriferia “pore bearers”
Aggregation of specialized cells
o Cells are independent from each other & do not form true tissues & organs
o Simplest multicellular animals
Nearly all are marine
o Sessile
o Variety of color, shape, and sizes
o Ostia (tiny pores) allow water to enter and circulate through series of canals where plankton and
organic particles are filtered & eaten
o Flexible skeletal frame gives the spongy texture
o If cells separated can even regroup and form new sponge
Outer surface covered with flat cells called pinacocytes & pore cells (porocytes) which allows water to
enter
Water pumped into larger feeding chamber lined with collar cells (choanocytes)
Each choanocytes has flagellum the creates currents and a thin collar that traps food particles, which is
ingested by body of cell
Water leaves through osculum, large opening at top of sponge
Type of suspension feeders that actively filter food particles (filter feeders)
Marine sponges show more complex arrangement with collar cells are restricted to chambers connected to
outer pores by a network of channels
Marine sponges have single osculum but have several oscula which serves as exit from many canals
o Helps meet higher demands for water flow for larger sponges
Large sponges have spicules that are transparent made of siliceous or calcareous supporting structures of
different shapes and sizes
Skeleton made of protein sponging
o Some may spicules, spongin, or both
o Wandering cells, amebocytes, secret spicules and sponging, transport and store food particles, and
transform into other types ifcells to quickly repair damage to the sponge
Reproduce asexually
o If piece breaks off, it can form new sponge
Reproduce sexually
o Specialized collar cells or amebocytes can turn into gametes
o Large nutrient rich egg and smaller sperm cell with flagellum
Most are hermaphrodites
Some have separate male and female organisms
Typically broadcast spawning
Egg retained inside of body until fertilization
Early development takes place inside
Flagellated sphere of cells (larva) is called parenchymula larva is planktonic & drifts with currents
Settles & metamorphosis into juvenile
Live from the poles to tropics
o Largest number of species in shallow tropical waters
o Branching tubular, volcano-like masses
o Encrusting sponges are thin brightly colored growths on rocks
Glass sponges live anchored in deep water sediments & have siliceous spicules (lace-like)
Boring sponges bore thin channels through calcium carbonate such as oysters shells and corals
Sclerosponges (coralline sponges) calcium carbonate skeleton forms beneath body of sponge
Some bath sponges are harvested in Gulf of Mexico and eastern Mediterranean
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The spongin are the fibers that remain after the death of a sponged