 | This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations .(March 2016) |
Gemmules are internal buds found in sponges and are involved in asexual reproduction. It is an asexually reproduced mass of cells, that is capable of developing into a new organism i.e., an adult sponge.
Asexual reproduction in sponges occurs via budding, either by external or internal buds. The internal buds are called gemmules. Only endogenous types of buds develop into new sponges.
Gemmules are resistant to desiccation (drying out), freezing, and anoxia (lack of oxygen) and can lie around for long periods of time. Gemmules are analogous to a bacterium's endospore and are made up of amoebocytes surrounded by a layer of spicules and can survive conditions that would kill adult sponges. When the environment becomes less hostile, the gemmule resumes growing.
Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the full set of genes of their single parent. Asexual reproduction is the primary form of reproduction for single-celled organisms such as archaea and bacteria. Many eukaryotic organisms including plants, animals, and fungi can also reproduce asexually. In vertebrates, the most common form of asexual reproduction is parthenogenesis, which is typically used as an alternative to sexual reproduction in times when reproductive opportunities are limited.
Sponges, the members of the phylum Porifera, are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells.
Parazoa are a taxon with sub-kingdom category that is located at the base of the phylogenetic tree of the animal kingdom in opposition to the sub-kingdom Eumetazoa; they group together the most primitive forms, characterized by not having proper tissues or that, in any case, these tissues are only partially differentiated. They generally group a single phylum, Porifera, which lack muscles, nerves and internal organs, which in many cases resembles a cell colony rather than a multicellular organism itself. All other animals are eumetazoans, which do have differentiated tissues.
Budding is a type of asexual reproduction in which a new organism develops from an outgrowth or bud due to cell division at one particular site. For example, the small bulb-like projection coming out from the yeast cell is known as a bud. Since the reproduction is asexual, the newly created organism is a clone and excepting mutations is genetically identical to the parent organism. Organisms such as hydra use regenerative cells for reproduction in the process of budding.
Plant propagation is the process by which new plants grow from a variety of sources: seeds, cuttings, and other plant parts. Plant propagation can also refer to the man-made or natural dispersal of seeds.
The Doliolida are an order of small marine animals of the subphylum Tunicata. They are in the class Thaliacea, which also includes the salps and pyrosomes. The doliolid body is small, typically 1–2 mm long, and barrel-shaped; it features two wide siphons, one at the front and the other at the back end, and eight or nine circular muscle strands reminiscent of barrel bands.
Demosponges (Demospongiae) are the most diverse class in the phylum Porifera. They include 76.2% of all species of sponges with nearly 8,800 species worldwide. They are sponges with a soft body that covers a hard, often massive skeleton made of calcium carbonate, either aragonite or calcite. They are predominantly leuconoid in structure. Their "skeletons" are made of spicules consisting of fibers of the protein spongin, the mineral silica, or both. Where spicules of silica are present, they have a different shape from those in the otherwise similar glass sponges. Some species, in particular from the Antarctic, obtain the silica for spicule building from the ingestion of siliceous diatoms.
Fragmentation in multicellular or colonial organisms is a form of asexual reproduction or cloning, where an organism is split into fragments. Each of these fragments develops into mature, fully grown individuals that are clones of the original organism.
Plant reproduction is the production of new offspring in plants, which can be accomplished by sexual or asexual reproduction. Sexual reproduction produces offspring by the fusion of gametes, resulting in offspring genetically different from either parent. Asexual reproduction produces new individuals without the fusion of gametes, resulting in clonal plants that are genetically identical to the parent plant and each other, unless mutations occur.
Suberites domuncula is a species of sea sponge belonging to the family Suberitidae.
Archaeocytes or amoebocytes are amoeboid cells found in sponges. They are totipotent and have varied functions depending on the species. The structure of these cells match to that of the stem cells as of containing high cytoplasmic content that helps the cells to morph according to their function.
Anheteromeyenia argyrosperma is a freshwater sponge found across North America.
Spongilla lacustris is a species of freshwater sponge from the family Spongillidae. It inhabits freshwater rivers and lakes, often growing under logs or rocks. Lacustris is a Latin word meaning "related to or associated with lakes". The species ranges from North America to Europe and Asia. It is the most common freshwater sponge in central Europe. It is the most widespread sponge in Northern Britain, and is one of the most common species of sponges in lakes and canals. Spongilla lacustris have the ability to reproduce both sexually and asexually. They become dormant during winter. The growth form ranges from encrusting, to digitate, to branched, depending upon the quality of the habitat.
Euplectella is a genus of glass sponges which includes the well-known Venus' Flower Basket. Glass sponges have a skeleton made up of silica spicules that can form geometric patterns. These animals are most commonly found on muddy sea bottoms in the Western Pacific and Indian Oceans. They are sessile organisms and do not move once attached to a rock. They can be found at depths between 100 m and 1000 m but are most commonly found at depths greater than 500 m.
Suberites ficus is a species of sponge in the family Suberitidae. It is sometimes known as the sea orange sponge.
Statoblasts are a means to reproduce asexually by a method that is unique among bryozoans and enables a colony's lineage to survive the variable and uncertain conditions of freshwater environments. Statoblasts are masses of cells that function as "survival pods" rather like the gemmules of sponges. Statoblasts form on the funiculus (cord) connected to the parent's gut, which nourishes them. As they grow, statoblasts develop protective bivalve-like shells made of chitin. When they mature, some types stick to the parent colony, some fall to the bottom, some contain air spaces that enable them to float, and some remain in the parent's cystid to re-build the colony if it dies. Statoblasts can remain dormant for considerable periods, and while dormant can survive harsh conditions such as freezing and desiccation. They can be transported across long distances by animals, floating vegetation, currents and winds. When conditions improve, the valves of the shell separate and the cells inside develop into a zooid that tries to form a new colony. A study estimated that one group of colonies in a patch 1 square meter (11 sq ft) produced 800,000 statoblasts.
Aplysina fistularis, also known as the yellow tube sponge, is a species of sea sponge in the order Verongiida. Aplysina fistularis is a golden or orange-brown color with a conulose surface. The animal is abundant in the Caribbean, where it is commonly found in reefs of open water areas. This sponge was first described by the Prussian zoologist Peter Simon Pallas in 1766.
Oscarella lobularis is a species of sponge in the order Homosclerophorida. It is native to the northeastern Atlantic Ocean and the Mediterranean Sea, where it forms encrusting colonies on rocks and other hard surfaces.
Oscarella tuberculata is a species of sponge in the order Homosclerophorida. It is endemic to the Mediterranean Sea, where it forms encrusting colonies on rocks and other hard surfaces.
 | This poriferan- (or sponge-) related article is a stub. You can help Wikipedia by expanding it. |
