PHYLUM BRYOZOA
Bryozoans hardly move. They attach to a hard surface. They live in colonies.
Zooids – small animals that make up the whole Bryozoa.
Despite being made up of small animals, Bryozoans can actually reach up to 3 feet in
length.
General Characteristics
• Bilaterally symmetrical
• Mostly colonial organisms
• Triploblastic body (3 germ layers: endoderm, ectoderm, mesoderm)
• True coelom body cavity (parts of the system is surrounded by body fluids)
• U-shaped gut
• With tissues and organs but absence of organ systems
• Has a central ganglion (simple nervous system)
The basis of its symmetry is not immediately seen as its colony. It is best seen under a
microscope since each bryozoan is very small (0.5 – 1 mm).
The lophophores seem to flutter while feeding.
Reemergence of the tentacles take a while.
Distinct Characteristics
• BODY PARTS
o Lophophore – a ciliated ring of tentacles centered on the mouth used as
filter feeding device
o U-shaped gut – a long stomach in which ingested particles are mixed
thoroughly with vigorous peristaltic contractions.
o Funiculus – a thin cord of tissue loosely joining the end of the gut to the
colony wall; the site of statoblast production and spermatogenesis.
o Orifice – a single opening where the lophophore protrudes
o Operculum – a door-like structure which closes the orifice when the
lophophore is extracted.
Cnidaria-Bryozoa Similarities Table
CNIDARIA SIMILARITIES BRYOZOA
• radial symmetry • colonial • bilateral symmetry
• diploblastic body • aquatic habitats • triploblastic body
• nerve net • sexual and asexual • central ganglion
• stinging tentacles reproduction • lophophore
• true coelom
, Mode of Life
• MOVEMENT
o most bryozoans are sessile and attached to a solid substrate.
o a few colonies are able to creep about.
o a few species of non-colonial bryozoans live and move about in the
species between sand grains.
• HABITAT
o Marine – mostly in shallow seas and nearshore.
o Freshwater – organisms of class phylactolaemata.
• FEEDING MECHANISM – filter feeding
• REPRODUCTION: ASEXUAL
o Budding of more zooids in a bryozoan colony (zoarium)
o In freshwater bryozoans, formation of statoblasts
o Statoblast – masses of cells surrounded by chitinous valves known; can
remain dormant and when conditions are favorable, germinates, and
forms a new zooid.
o Hermaphroditic – individuals containing both ovaries and testes however
may not be the same state of maturity at the same time.
o Some species shed both eggs and sperm directly into the water where
they fertilize.
o Most species brood eggs within the zooecium and capture free-swimming
sperm to fertilize the eggs.
o Gives rise to a new parent animal (ancestrula) that would later establish a
colony of its own.
Anatomy and Structure
• Hard Parts
o Zooecium – exoskeleton; calcareous or siliceous
o Three kinds of Zooecia within a Zooarium: Autopores, Mesopores,
Acanthopores
o Autopores – houses the individual zooids; large diameter; with short
horizontal dividing walls.
o Mesopores – small diameter; adjacent to autopores.
o Acanthopores – scattered tiny thick-walled tubes; located at junction
between the autopores and mesopores.
• Soft Parts
o Lophophore – a ring of tentacles used for food-getting.
o U-shaped gut – composed of esophagus, stomach, and intestine.
Basis of Classification
Bryozoans hardly move. They attach to a hard surface. They live in colonies.
Zooids – small animals that make up the whole Bryozoa.
Despite being made up of small animals, Bryozoans can actually reach up to 3 feet in
length.
General Characteristics
• Bilaterally symmetrical
• Mostly colonial organisms
• Triploblastic body (3 germ layers: endoderm, ectoderm, mesoderm)
• True coelom body cavity (parts of the system is surrounded by body fluids)
• U-shaped gut
• With tissues and organs but absence of organ systems
• Has a central ganglion (simple nervous system)
The basis of its symmetry is not immediately seen as its colony. It is best seen under a
microscope since each bryozoan is very small (0.5 – 1 mm).
The lophophores seem to flutter while feeding.
Reemergence of the tentacles take a while.
Distinct Characteristics
• BODY PARTS
o Lophophore – a ciliated ring of tentacles centered on the mouth used as
filter feeding device
o U-shaped gut – a long stomach in which ingested particles are mixed
thoroughly with vigorous peristaltic contractions.
o Funiculus – a thin cord of tissue loosely joining the end of the gut to the
colony wall; the site of statoblast production and spermatogenesis.
o Orifice – a single opening where the lophophore protrudes
o Operculum – a door-like structure which closes the orifice when the
lophophore is extracted.
Cnidaria-Bryozoa Similarities Table
CNIDARIA SIMILARITIES BRYOZOA
• radial symmetry • colonial • bilateral symmetry
• diploblastic body • aquatic habitats • triploblastic body
• nerve net • sexual and asexual • central ganglion
• stinging tentacles reproduction • lophophore
• true coelom
, Mode of Life
• MOVEMENT
o most bryozoans are sessile and attached to a solid substrate.
o a few colonies are able to creep about.
o a few species of non-colonial bryozoans live and move about in the
species between sand grains.
• HABITAT
o Marine – mostly in shallow seas and nearshore.
o Freshwater – organisms of class phylactolaemata.
• FEEDING MECHANISM – filter feeding
• REPRODUCTION: ASEXUAL
o Budding of more zooids in a bryozoan colony (zoarium)
o In freshwater bryozoans, formation of statoblasts
o Statoblast – masses of cells surrounded by chitinous valves known; can
remain dormant and when conditions are favorable, germinates, and
forms a new zooid.
o Hermaphroditic – individuals containing both ovaries and testes however
may not be the same state of maturity at the same time.
o Some species shed both eggs and sperm directly into the water where
they fertilize.
o Most species brood eggs within the zooecium and capture free-swimming
sperm to fertilize the eggs.
o Gives rise to a new parent animal (ancestrula) that would later establish a
colony of its own.
Anatomy and Structure
• Hard Parts
o Zooecium – exoskeleton; calcareous or siliceous
o Three kinds of Zooecia within a Zooarium: Autopores, Mesopores,
Acanthopores
o Autopores – houses the individual zooids; large diameter; with short
horizontal dividing walls.
o Mesopores – small diameter; adjacent to autopores.
o Acanthopores – scattered tiny thick-walled tubes; located at junction
between the autopores and mesopores.
• Soft Parts
o Lophophore – a ring of tentacles used for food-getting.
o U-shaped gut – composed of esophagus, stomach, and intestine.
Basis of Classification
