|
Gonozooid
A gonozooid is any of the reproductive individuals of tunicate, Bryozoa, bryozoan, or Hydrozoa, hydrozoan colonies that produce Gamete, gametes. Gonozooids may play a role in Division of labour, labour division or in alternation of generations. A gonozooid typically has hardly any other function than reproduction, amounting to little more than a motility, motile gonad. The production of gonozooids amounts to one aspect of certain classes of alternation of generations. In biological terms the various forms are examples of Evolutionarily stable strategy, evolutionary strategies and are largely Convergent evolution, analogous rather than Homology (biology), homologous; the gonozooid phases of tunicates and bryozoans, for instance, did not originate from a common ancestor. Examples of species with gonozooids ''Hydractinia symbiolongicarpus'' Polyps from the cnidarian ''Hydractinia symbiolongicarpus'' form colonies where labour is divided between reproduction (gonozooids), feeding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bryozoa
Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic animal, aquatic invertebrate animals, nearly all living in sedentary Colony (biology), colonies. Typically about long, they have a special feeding structure called a lophophore, a "crown" of tentacles used for filter feeder, filter feeding. Most Marine (ocean), marine bryozoans live in tropical waters, but a few are found in oceanic trenches and polar waters. The bryozoans are classified as the Stenolaemata, marine bryozoans (Stenolaemata), Phylactolaemata, freshwater bryozoans (Phylactolaemata), and Gymnolaemata, mostly-marine bryozoans (Gymnolaemata), a few members of which prefer brackish water. 5,869living species are known. Originally all of the crown group Bryozoa were colonial, but as an adaptation to a mesopsammal (interstitial spaces in marine sand) life or to deep-sea habitats, secondarily solitary forms have since evolved. Solitary species have been described i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tunicate
Tunicates are marine invertebrates belonging to the subphylum Tunicata ( ). This grouping is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one time called Urochordata, and the term urochordates is still sometimes used for these animals. Despite their simple appearance and very different adult form, their close relationship to the vertebrates is certain. Both groups are chordates, as evidenced by the fact that during their mobile larval stage, tunicates possess a notochord, a hollow dorsal nerve cord, pharyngeal slits, post-anal tail, and an endostyle. They resemble a tadpole. Tunicates are the only chordates that have lost their Myomere, myomeric segmentation, with the possible exception of the seriation of the gill slits. However, Doliolida, doliolids still display segmentation of the muscle bands. Some tunicates live as solitary individuals, but others replicate by budding and be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrozoa
Hydrozoa (hydrozoans; from Ancient Greek ('; "water") and ('; "animals")) is a taxonomy (biology), taxonomic class (biology), class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline water. The colony (biology), colonies of the colonial species can be large, and in some cases the specialized individual animals cannot survive outside the colony. A few genus, genera within this class live in freshwater ecosystem, freshwater habitats. Hydrozoans are related to jellyfish and corals, which also belong to the phylum (biology), phylum Cnidaria. Some examples of hydrozoans are the freshwater jelly (''Craspedacusta sowerbyi''), freshwater polyps (''Hydra (genus), Hydra''), ''Obelia'', Portuguese man o' war (''Physalia physalis''), chondrophores (Porpitidae), and pink-hearted hydroids (''Tubularia''). Anatomy Most hydrozoan species include both a polyp (zoology), polypoid and a medusa (biology), medusoid stage in their Biological ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Variance
Genetic variance is a concept outlined by the England, English biologist and statistics, statistician Ronald Fisher in his Fisher's fundamental theorem of natural selection, fundamental theorem of natural selection. In his 1930 book ''The Genetical Theory of Natural Selection'', Fisher postulates that the rate of change of fitness (biology), biological fitness can be calculated by the genetic variance of the fitness itself. Fisher tried to give a statistical formula about how the change of fitness in a population can be attributed to changes in the allele frequency. Fisher made no restrictive assumptions in his formula concerning fitness parameters, mate choices or the number of alleles and locus (genetics), loci involved. Definition Phenotypic variance, usually combines the genotype variance with the environmental variance. Genetic variance has three major components: the additive genetic variance, dominance variance, and epistatic variance. Additive genetic variance involves ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metamorphosis
Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some insects, jellyfish, fish, amphibians, mollusks, crustaceans, cnidarians, echinoderms, and tunicates undergo metamorphosis, which is often accompanied by a change of nutrition source or behavior. Animals can be divided into species that undergo complete metamorphosis (" holometaboly"), incomplete metamorphosis (" hemimetaboly"), or no metamorphosis (" ametaboly"). Generally organisms with a larval stage undergo metamorphosis, and during metamorphosis the organism loses larval characteristics. Etymology The word ''metamorphosis'' derives from Ancient Greek , "transformation, transforming", from ('), "after" and ('), "form". Hormonal control In insects, growth and metamorphosis are controlled by hormones synthesized by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sterility (physiology)
Sterility is the physiological inability to effect sexual reproduction in a living thing, members of whose kind have been produced sexually. Sterility has a wide range of causes. It may be an inherited trait, as in the mule; or it may be acquired from the environment, for example through physical injury or disease, or by exposure to radiation. Sterility is the inability to produce a biological child, while infertility is the inability to conceive after a certain period. Sterility is rarely discussed in clinical literature and is often used synonymously with infertility. Infertility affects about 12-15% of couples globally. Still, the prevalence of sterility remains unknown. Sterility can be divided into three subtypes natural, clinical, and hardship. Natural sterility is the couple's physiological inability to conceive a child. Clinical sterility is natural sterility for which treatment of the patient will not result in conception. Hardship sterility is the inability to take adv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Celleporella Hyalina
''Celleporella hyalina'' is a species of bryozoans belonging to the family Hippothoidae. It has almost cosmopolitan distribution In biogeography, a cosmopolitan distribution is the range of a taxon that extends across most or all of the surface of the Earth, in appropriate habitats; most cosmopolitan species are known to be highly adaptable to a range of climatic and en .... The species has numerous subspecies, eg: * ''Celleporella hyalina'' subsp. ''hyalina'' * ''Celleporella hyalina'' subsp. ''marcusi'' (Morris, 1980) References {{Taxonbar, from=Q6402965 Bryozoans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Budding
Budding or blastogenesis 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. In hydra, a bud develops as an outgrowth due to repeated cell division of the parent body at one specific site. These buds develop into tiny individuals and, when fully mature, detach from the parent body and become new independent individuals. Internal budding or endodyogeny is a process of asexual reproduction, favored by parasites such as '' Toxoplasma gondii''. It involves an unusual process in which two daughter cells are produced inside a mother cell, which is then consumed by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asexual Reproduction
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 and thus the newly created individual is genetically and physically similar to the parent or an exact clone of the parent. Asexual reproduction is the primary form of reproduction for single-celled organisms such as archaea and eubacteria, bacteria. Many Eukaryote, eukaryotic organisms including plants, animals, and Fungus, fungi can also reproduce asexually. In Vertebrate, 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. Some Monitor lizard, monitor lizards, including Komodo dragons, can reproduce asexually. While all prokaryotes reproduce without the fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Egg Cell
The egg cell or ovum (: ova) is the female Reproduction, reproductive cell, or gamete, in most anisogamous organisms (organisms that reproduce sexually with a larger, female gamete and a smaller, male one). The term is used when the female gamete is not capable of movement (non-motile). If the male gamete (sperm) is capable of movement, the type of sexual reproduction is also classified as oogamous. A nonmotile female gamete formed in the oogonium of some algae, fungi, oomycetes, or bryophytes is an oosphere. When fertilized, the oosphere becomes the oospore. When egg and sperm fuse together during fertilisation, a diploid cell (the zygote) is formed, which rapidly grows into a new organism. History While the non-mammalian animal egg was obvious, the doctrine ''ex ovo omne vivum'' ("every living [animal comes from] an egg"), associated with William Harvey (1578–1657), was a rejection of spontaneous generation and preformationism as well as a bold assumption that mammals als ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Doliolum Nationalis
''Doliolum'' is a genus of tunicates, the members of which move via jet propulsion. A detailed description can be found in the article, "On the anatomical structure of the trophozooid of Doliolum denticulatum." Species The World Register of Marine Species lists the following species: World Register of Marine Species. Retrieved 2011-11-17. *'' Doliolum denticulatum
''Doliolum'' is a genus of tunicates, the members of which move via jet propulsion. A detailed description can be found in the article, "On the anatomical structure of the trophozooid of Doliolum denticulatum."
Species
The World Register of Mar ... ...
[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydractinia Symbiolongicarpus
''Hydractinia symbiolongicarpus'' is one of the 30 + '' Hydractinia'' species known worldwide. This saltwater animal, from here on referred to as ''Hydractinia'', is at the base of the Cnidaria phylum and in many ways, is similar to the freshwater '' Hydra''. In the wild, ''Hydractinia'' feed on smaller invertebrates found in the shallow mud, however in laboratory environments they are fed brine shrimp. ''Hydractinia symbiolongicurpus'' and its sibling species, '' Hydractinia echinata'', are the two species from the genus ''Hydractinia'' on which most work has been published. Description ''Hydractinia'' consist of a network of gastrovascular canals embedded in a plate of tissue called the mat. When gastrovascular canals extend outside of the mat, they are called stolons. The stolon tips on the outer edge of the colony secrete SIF (Stolon Inducing Factor) allowing for the creation of branching stolons In the field, colonies exhibit morphologies that range from highly stolon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
