INTRODUCTION TO BRYOZOA

1. INTRODUCTION TO BRYOZOA

2. 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 formcolonies • Commonly found attached to the rocks and seaweeds on the seacoast.

3. 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)

4. 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

5. “Colonial” -refers to a life style or habit where members of the same species live together. • Colonial animals include corals , hydroids andgraptolites as well as bryozoans. • the entire complex is called a “colony” • Individual members of a bryozoan colony are called “zooids”

6. (~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

8. 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

9. There are at least two kinds of zooid - the flower-shaped feeding lophophores and these translucent cylindrical forms. 

10. 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.

12. 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 

13. 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)

14. 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.

15. 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

16. 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.

17. When feeding, the zooid extends the lophophore outwards; • when resting it is withdrawn into the mouth to protect it from predators.

18. 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.

19. 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- CambrianPaleozoic 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

20. 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.

21. 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.

22. 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. The PennsylvanianSeptopora exemplifies the branching form of some bryozoan colonies. This specimen is from the Kansas City Formation, Jackson County, Missouri.