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 "Bryozoa", from Ernst Haeckel's Kunstformen der Natur, 1904
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Stenolaemata |
Bryozoans are tiny colonial animals that generally build stony skeletons of calcium carbonate, superficially similar to coral (although some species lack any calcification in the colony and instead have a mucilaginous structure. Ernst Heinrich Philipp August Haeckel ( February 16, 1834 — August 9, 1919)also written von Haeckel, was an eminent German Kunstformen der Natur ( German: Art Forms of Nature) is a book of lithographic and Autotype prints by German biologist The Lophotrochozoa (ləˌfɒtroʊkəˈzoʊə "crest-bearing animals" are one of three major groupings of Protostome animals Stenolaemata are a class of marine Bryozoans with tubular zooids with strongly calcified walls Gymnolaemata is a class of the phylum Bryozoa. Gymnolaemata typically live under seawater and grow on surfaces of rocks Kelps and even in some cases on animal species In Biology, the skeleton is a strong and often a rigid framework that supports the body of an animal holding it upright and giving it shape and strength (Also skeletal Calcium carbonate is a Chemical compound with the Chemical formula Ca[[Carbon C]] O 3 Corals are Marine organisms from the class Anthozoa and exist as small Sea anemone –like Polyps typically in colonies of many ) Bryozoa are also known as moss animals or moss animacules (which is the literal Greek translation of bryozoa) or as sea mats. They generally prefer warm, tropical waters, but are known to occur worldwide. There are about 8,000 living species, with several times that number of fossil forms known. In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank.
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Ecology
Most species of Bryozoan live in marine environments, though there are about 50 species which inhabit freshwater. In their aquatic habitats, bryozoans may be found on all types of hard substrates: sand grains, rocks, shells, wood, blades of kelp, pipes and ships may be heavily encrusted with bryozoans. Sand is a naturally occurring Granular material composed of finely divided rock and Mineral particles Wood is hard fibrous lignified structural tissue produced as secondary Xylem in the stems of Woody plants notably trees but also shrubs Kelp are large Seaweeds ( Algae) belonging to the Brown algae and classified in the order Laminariales Some bryozoan colonies, however, do not grow on solid substrates, but form colonies on sediment. Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of While some species have been found at depths of 8,200 m (27,000 ft), most bryozoans inhabit much shallower water. The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International A foot (plural feet or foot; symbol or abbreviation ft or sometimes &prime – the prime symbol) is a non-SI unit Most bryozoans are sessile and immobile, but a few colonies are able to creep about, and some non-colonial bryozoans live and move about in the spaces between sand grains. One remarkable species makes its living while floating in the Southern Ocean. The Southern Ocean, also known as the Great Southern Ocean, the Antarctic Ocean and the South Polar Ocean, comprises the southernmost waters of Fossil bryozoans are common throughout the world in sedimentary rocks representing shallow marine habitats, especially in rocks of post-Cambrian Paleozoic age. FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system. Sedimentary rock is one of the three main rock types (the others being igneous and Metamorphic rock) The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with The Paleozoic or Palaeozoic Era (from the Greek palaio (παλαιο "old" and zoe (ζωη "life" meaning "ancient life"
Bryozoans are also colony-forming animals. Many millions of individuals can form one colony. The colonies range from millimeters to meters in size, but the individuals that make up the colonies are tiny, usually less than a millimeter long. In each colony, different individuals assume different functions. Some individuals gather up the food for the colony (autozooids), others depend on them (heterozooids). Some individuals are devoted to strengthening the colony (kenozooids), and still others to cleaning the colony (vibracula). There is only a single known solitary species, Monobryozoon ambulans, which does not form colonies.
Anatomy
Bryozoan skeletons grow in a variety of shapes and patterns: mound-shaped, lacy fans, branching twigs, and even corkscrew-shaped. Their skeletons have numerous tiny openings, each of which is the home of a minute animal called a zooid. In Biology, the skeleton is a strong and often a rigid framework that supports the body of an animal holding it upright and giving it shape and strength (Also skeletal They also have a coelomate body with a looped alimentary canal or gut, opening at the mouth and terminating at the anus. By the broadest definition a body cavity is any fluid filled space in a Multicellular organism. The mouth, buccal cavity, or oral cavity is the first portion of the Alimentary canal that receives food and begins digestion by mechanically breaking up The anus is an opening at the opposite end of an Animal 's Digestive tract from the Mouth. They feed with a specialized, ciliated structure called a lophophore, which is a crown of tentacles surrounding the mouth. A cilium (plural cilia) is an Organelle found in eukaryotic cells Cilia are tail-like projections extending approximately The lophophore (ˈlɒfəfɔər is a characteristic feeding organ possessed by three major groups of animals the Brachiopoda, Bryozoa, and Phoronida. Tentacles can refer to the elongated flexible organs that are present in some animals especially Invertebrates and sometimes to the hairs of the leaves of some insectivorous Their diet consists of small microorganisms, including diatoms and other unicellular algae. Diatoms ( Greek: (dia = "through" + (temnein = "to cut" i Algae ( sing. alga are a large and diverse group of simple typically Autotrophic organisms ranging from Unicellular to Multicellular forms In turn, bryozoans are preyed on by grazing organisms such as sea urchins and fish. Sea urchins are small globular spiny sea cat animals composing most of class Echinoidea. Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two Bryozoans do not have any defined respiratory, or circulatory systems due to their small size. However, they do have a simple nervous system and a hydrostatic skeletal system. Several studies have been undertaken on the crystallography of bryozoan skeletons, revealing a complex fabric suite of oriented calcite or aragonite crystallites within an organic matrix - see for example Hall et al. Calcite is a carbonate mineral and the most stable polymorph of Calcium carbonate ( Ca[[carbon C]] O 3 Aragonite is a Carbonate mineral, one of the two common naturally occurring polymorphs of Calcium carbonate, Ca[[carbon C]] O 3 (2002).
The tentacles of the bryozoans are ciliated, and the beating of the cilia creates a powerful current of water which drives water together with entrained food particles (mainly phytoplankton) towards the mouth. A cilium (plural cilia) is an Organelle found in eukaryotic cells Cilia are tail-like projections extending approximately The gut is U-shaped, and consists of a pharynx which passes into the esophagus, followed by the stomach, which has three parts: the cardia, the caecum, and the pylorus. The pharynx (plural pharynges) is the part of the Neck and Throat situated immediately Posterior to (behind the Mouth and Nasal The esophagus or oesophagus (see American and British English spelling differences) sometimes known as the gullet, is an organ in In Human anatomy, the stomach is a J-shaped hollow muscular organ of the Gastrointestinal tract involved in the second phase of Digestion, following The cardia (also known as Z-line or esophagogastric junction or gastroesophageal junction) is the anatomical term for the junction orifice of The cecum or caecum (from the Latin caecus meaning Blind) is a pouch connected to the Ascending colon of the Large The pylorus (from Greek πυλωρος = "gate guard" is the region of the Stomach that connects to the Duodenum. The pylorus leads to an intestine and a short rectum terminating at the anus, which opens outside the lophophore. The rectum (from the Latin rectum intestinum, meaning straight intestine) is the final straight portion of the Large intestine in some Mammals The lophophore (ˈlɒfəfɔər is a characteristic feeding organ possessed by three major groups of animals the Brachiopoda, Bryozoa, and Phoronida. In some groups, notably some ctenostomes, a specialized gizzard may be formed from the proximal part of the cardia. The gizzard, also referred to as the ventriculus, gastric mill, and gigerium, is an organ in the digestive tract found in Birds Reptiles Gut and lophophore are the principal components of the polypide. The polypide in Bryozoans encompasses most of the organs and tissues of each individual zooid Cyclical degeneration and regeneration of the polypide is characteristic of marine bryozoans. After the final polypide degeneration, the skeletal aperture of the feeding zooid may become sealed by the secretion of a terminal diaphragm. Septa (singular septum) are thin walls or partitions between the internal chambers ( Camerae) of the shell of a Cephalopod, namely Nautiloids In many bryozoans only the zooids within a few generations of the growing edge are in an actively feeding state; older, more proximal zooids (e. g. in the interiors of bushy colonies) are usually dormant.
Because of their small size, bryozoans have no need of a blood system. Blood is a specialized Bodily fluid that delivers necessary substances to the body's cells such as nutrients and oxygen—and transports Waste products Gaseous exchange occurs across the entire surface of the body, but particularly through the tentacles of the lophophore.
Bryozoans can reproduce both sexually and asexually. All bryozoans, as far as is known, are hermaphroditic (meaning they are both male and female). A hermaphrodite is an organism having both male and female reproductive organs Asexual reproduction occurs by budding off new zooids as the colony grows, and is the main way by which a colony expands in size. Asexual reproduction is a form of reproduction which does not involve Meiosis, Ploidy reduction or Fertilization. If a piece of a bryozoan colony breaks off, the piece can continue to grow and will form a new colony. A colony formed this way is composed entirely of clones (genetically identical individuals) of the first animal, which is called the ancestrula. Cloning in Biology is the process of producing populations of genetically-identical individuals that occurs in nature when organisms such as Bacteria, Insects
One species of bryozoan, Bugula neritina, is of current interest as a source of cytotoxic chemicals, bryostatins, under clinical investigation as anti-cancer agents. Cytotoxicity is the quality of being toxic to cells Examples of toxic agents are a Chemical substance, an Immune cell or some types of Venom Bryostatins are a group of Macrolide Lactones first discovered in the late 1960s in a species of Bryozoan, Bugula neritina.
Fossils
Fossil bryozoans are found in rocks beginning in the early Ordovician. FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system. The Early Ordovician, also called the Lower Ordovician by Geologists is the first subdivision of the Ordovician period and marked a great diversification They were often major components of Ordovician 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. Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of The benthic zone is the ecological region at the lowest level of a Body of water such as an Ocean or a Lake, including the sediment surface and some sub-surface During the Mississippian (354 to 323 million years ago) bryozoans were so common that their broken skeletons form entire limestone beds. Limestone is a Sedimentary rock composed largely of the Mineral Calcite ( Calcium carbonate: CaCO3 Bryozoan fossil record comprises more than 1,000 described species. It is plausible that the Bryozoa existed in the Cambrian but were soft-bodied or not preserved for some other reason; perhaps they evolved from a phoronid-like ancestor at about this time. The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with Phoronids (' Phoronida') commonly known as horseshoe worms, are a relatively small animal Phylum: twenty species are known in two genera
Bryozoans are important members of sclerobiont (organisms which dwell on hard substrates such as shells and rocks) communities in the fossil record and in the Recent. For a review of sclerobiont evolution, history and ecology, see Taylor & Wilson (2003).
Most fossil bryozoans have mineralized skeletons. The skeletons of individual zooids vary from tubular to box-shaped and contain a terminal aperture from which the lophophore is protruded to feed. The lophophore (ˈlɒfəfɔər is a characteristic feeding organ possessed by three major groups of animals the Brachiopoda, Bryozoa, and Phoronida. No pores are present in the great majority of Ordovician bryozoans, but skeletal evidence shows that epithelia were continuous from one zooid to the next. In biology and medicine epithelium is a tissue composed of cells that line the cavities and surfaces of structures throughout the body
With regard to the bryozoan groups lacking mineralized skeletons, the statoblasts of freshwater phylactolaemates have been recorded as far back as the Permian, and the ctenostome fossils date only from the Triassic. The Permian is a geologic period and system that extends from 299 The Triassic is a geologic period and system that extends from about 251 to 199 Ma (million years ago
One of the most important events during bryozoan evolution was the acquisition of a calcareous skeleton and the related change in the mechanism of tentacle protrusion. The rigidity of the outer body walls allowed a greater degree of zooid contiguity and the evolution of massive, multiserial colony forms.
Classification
The Bryozoans were formerly considered to contain two subgroups: the Ectoprocta and the Entoprocta, based on the similar bodyplans and mode of life of these two groups. Entoprocta (Gr εντος entos inside + προκτος proktos anus is a phylum of small aquatic Animals ranging in size from 0 (Some researchers also included the Cycliophora, which are thought to be closely related to the Entoprocta. Symbion is the name of a Genus of aquatic animals less than ½ mm wide found living attached to the bodies of cold-water lobsters ) However, the Ectoprocta are coelomate (possessing a body cavity) and their embryos undergo radial cleavage, while the Entoprocta are acoelemate and undergo spiral cleavage. By the broadest definition a body cavity is any fluid filled space in a Multicellular organism. In Embryology, cleavage is the division of cells in the early Embryo. In Embryology, cleavage is the division of cells in the early Embryo. Molecular studies are ambiguous about the exact position of the Entoprocta, but do not support a close relationship with the Ectoprocta. For these reasons, the Entoprocta are now considered a phylum of their own. [1] The removal of the 150 species of Entoprocta leaves Bryozoa synonymous with Ectoprocta; some authors have adopted the latter name for the group, but the majority continue to use the former.
References
- Hall, S. R. , Taylor, P. D. , Davis, S. A. and Mann, S. , 2002. Electron diffraction studies of the calcareous skeletons of bryozoans. Journal of Inorganic Biochemistry 88: 410-419. [1]
- Taylor, P. D. and Wilson, M. A. , 2003. Palaeoecology and evolution of marine hard substrate communities. Earth-Science Reviews 62: 1-103. [2]
- Sharp, J. H. , Winson, M. K. and Porter, J. S. 2007. Bryozoan metabolites: an ecological perspective. Natureal Product Reports 24: 659-673.
- ^ James W. Valentine (2004). On the origins of phyla. University of Chicago Press.
See also
External links
- Index to Bryozoa Bryozoa Home Page, was at RMIT; now bryozoa. The International Bryozoology Association ( IBA) is a Professional association with international membership specialising in Research of the Phylum net
- Other Bryozoan WWW Resources
- International Bryozoology Association official website
- Bryozoan Introduction
- The Phylum Ectoprocta (Bryozoa)
- Phylum Bryozoa at Wikispecies
- Bryozoans in the Connecticut River
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