Transcript INTRODUCTION_TO_BRYOZOA_2

INTRODUCTION TO BRYOZOA
Phylum Bryozoa
 Bryozoa commonly known “moss animals” (not moss
plants which is Bryophyta)
Greek words, bryon (moss) and zoon (animal)
 a phylum of aquatic invertebrate animals
 species form colonies
 Commonly found attached to the rocks and seaweeds on
the seacoast.
 abundant in modern marine environments
 some that superficially resemble corals
 in places, the skeletal remains are so abundant that the
fossils become an important rock-forming material.
Pore-tubed bryozoan
(Tubulipora pulcherrima)
 Most lived in tropical waters,
but a few occur in oceanic
trenches, and others are
found in polar waters
 Over 4,000 living species and
15,000 fossil species are
known
A fresh water Bryozoan colony
 “Colonial” -refers to a life style or habit where
members of the same species live together.
 Colonial animals include corals , hydroids and
graptolites as well as bryozoans.
 the entire complex is called a “colony”
 Individual members of a bryozoan colony are called
“zooids”
 (~0.2mm) zooids.
 These zooids secrete tubes, usually
of lime (CaCO3)
 All bryozoan have a Lophophore.

ring of ten tentacles surrounding
the mouth, each tentacle covered
with cilia.
Cilia (singular cilium) are hair like
projections surrounding the
tentacle
Section of a Bryozoan
Feeding Zooid
A lateral view, of a portion of a colony, of encrusting
bryozoans.
Moss Animals - microscopic
invertebrates
Colonies of Zooids
geometric piece of natural architecture is
produced by the animal
commonly called the sea-mat and
scientifically known as a bryozoan
There are at least two kinds of zooid the flower-shaped feeding lophophores
and these translucent cylindrical forms.
 Some bryozoans built colonies that grew from the
seafloor in branching structures; these fossils look like
something like twigs. Other species erected netlike
frameworks, while some spread like a crust on shells,
rocks, plants, and even other bryozoan colonies.
 Almost all the fossils are fragments of colonies; only
rarely is an entire colony preserved.
The colonies of Tabulipora, a
bryozoan found in Kansas,
sometimes were sheetlikeand
are sometimes found on other
fossils. Tabulipora is known from
theMississippian to the Permian.
Fenestella, another bryozoan found
in Kansas rocks, is one of the
bryozoans whose colonies had a
netlike structure. This fossil genus is
also known from the Mississippian to
thePermian (drawings by Al Kamb,
KU Natural History Museum,
Invertebrate Paleontology).
Ecology
 Most marine species live in tropical waters at depths
less than 100 metres (330 ft).
 Few have been found in deep-sea trenches,
around cold seeps, and others near the poles.
 may be found on all types of hard substrates:
sand grains, rocks, shells, wood, blades of kelp, pipes
and ships
 Most bryozoans are sessile and immobile, but a few
colonies are able to creep about, and a few species of
non-colonial bryozoans live and move about in the
spaces between sand grains.
 Their diet consists of small microorganisms,
including diatoms and other unicellular algae.
 Bryozoans are preyed on by grazing organisms such
as sea urchins and fish.
 also found in lakes and ponds, rivers and streams, and
estuaries (fresh water environment)
Reproduction & Development
 Bryozoans can reproduce both sexually and asexually.
 All Bryozoans, as far as is known,
are hermaphrodite (meaning they are both male and
female).
 All members of a colony are clones
 they are genetically identical, produced by asexual
reproduction (through budding) by the parent colony.
 most species the zooids are specialised to different
functions
 Autozooids-feeding zooids
 Heterozooids- non-feeding members
 Function include: sexual reproduction,
protection, locomotion, plumbing, structural
support
Feeding
 Most species are filter feeders that sieve small particles
mainly phytoplankton (microscopic floating plants), out
of the water.
 also feeds on diatoms, green algae, cyanobacteria, non-
photosynthetic bacteria, dinoflagellates
 In turn, bryozoans are preyed on by grazing organisms
such as sea urchins and fish.
 When feeding, the zooid extends the
lophophore outwards;
 when resting it is withdrawn into the mouth
to protect it from predators.
Respiration and Circulation
 there are no respiratory organs, heart or blood vessels.
 zooids absorb oxygen and eliminate carbon
dioxide through the body wall and especially the
lophophore
 methods to share nutrients and oxygen between zooids:
some have quite large gaps in the body walls, allowing the
coelomic fluid to circulate freely; in others the funiculi
(internal "little ropes") of adjacent zooids connect via small
pores in the body wall.
Fossils
 Fossil bryozoans are found in rocks beginning in the
early Ordovician
 Abundant in the Palaeozoic era.
 common throughout the world in sedimentary rocks
representing shallow marine habitats,
especially in rocks of post- Cambrian Paleozoic age.
 Major components of seabed communities and, like
modern-day bryozoans, played an important role
in sediment stabilization and binding as well as providing
sources of food for other benthic organisms
 During the Lower Carboniferous (Mississippian) 323 to
354 million years ago, bryozoans were so common that
their broken skeletons form entire limestone beds.
 Most fossil bryozoans have mineralized skeletons.
 Skeletons of individual zooids vary from tubular to
box-shaped
 Stratigraphic
Range: Lower Ordovician to Holocene.
 One of the most important
events during bryozoan evolution
was the acquisition of a
calcareous skeleton.
 The rigidity of the outer body
walls gave protection against
predators, a greater degree of
zooid contiguity, and the
evolution of massive, multiserial
colony forms.
Bryozoan fossils in an
Upper Ordovician oil shale
(Kukersite), northern Estonia.
The Pennsylvanian Septopora exemplifies
the branching form of some bryozoan
colonies. This specimen is from the Kansas
City Formation, Jackson County, Missouri.
Bryozoan fossils from the Topeka
Limestone in Kansas. These fossils were
deposited during the Pennsylvanian
Period, about 300 million years ago, and
illustrate the branching and netlike
forms of some bryozoan colonies.