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Nematocyst (dinoflagellate)
A nematocyst is a subcellular structure or organelle containing extrusive filaments found in two families of athecate dinoflagellates (a group of unicellular eukaryotes), the Warnowiaceae and Polykrikaceae. It is distinct from the similar subcellular structures found in the cnidocyte cells of cnidarians, a group of multicellular organisms including jellyfish and corals; such structures are also often called nematocysts (alternatively, ''cnidocysts'' or ''cnidae''), and cnidocytes are sometimes referred to as nematocytes. It is unclear whether the relationship between dinoflagellate and cnidarian nematocysts is a case of convergent evolution or common descent, although molecular evidence has been interpreted as supporting an endosymbiotic origin for cnidarian nematocysts. In polykrikoids the nematocyst is found associated with another extrusive organelle called the taeniocyst, a complex that has been described as synapomorphic for the genus '' Polykrikos''. The full range of f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polykrikos Kofoidii
''Polykrikos kofoidii'' is a species of phagotrophic marine pseudocolonial dinoflagellates that can capture and engulf other protist prey, including the toxic dinoflagellate, '' Alexandrium tamarense''. '' P. kofoidii'' is of scientific interest due to its status as a predator of other dinoflagellates, a behavior that is significant in the control of algal bloom An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in fresh water or marine water systems. It is often recognized by the discoloration in the water from the algae's pigments. The term ''algae'' encompass ...s. It has a complex life cycle of both vegetative (asexual) and sexual reproduction complicated by its pseudocolonial structure. References Protists described in 1914 Gymnodiniales Dinoflagellate species {{dinoflagellate-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coral
Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral reef, reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton. A coral "group" is a colony of very many cloning, genetically identical polyps. Each polyp is a sac-like animal typically only a few millimeters in diameter and a few centimeters in height. A set of tentacles surround a central mouth opening. Each polyp excretes an exoskeleton near the base. Over many generations, the colony thus creates a skeleton characteristic of the species which can measure up to several meters in size. Individual colonies grow by asexual reproduction of polyps. Corals also breed sexually by spawning: polyps of the same species release gametes simultaneously overnight, often around a full moon. Fertilized eggs form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prey
Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the host) and parasitoidism (which always does, eventually). It is distinct from scavenging on dead prey, though many predators also scavenge; it overlaps with herbivory, as seed predators and destructive frugivores are predators. Predation behavior varies significantly depending on the organism. Many predators, especially carnivores, have evolved distinct hunting strategies. Pursuit predation involves the active search for and pursuit of prey, whilst ambush predators instead wait for prey to present an opportunity for capture, and often use stealth or aggressive mimicry. Other predators are opportunistic or omnivorous and only practice predation occasionally. Most obligate carnivores are specialized for hunting. They may ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polykrikos
''Polykrikos'' (from Greek “poly” - many, and “krikos” – ring or circle) is one of the genera of family Polykrikaceae that includes athecate pseudocolony-forming dinoflagellates. ''Polykrikos'' are characterized by a sophisticated ballistic apparatus, named the nematocyst-taeniocyst complex, which allows species to prey on a variety of organisms. ''Polykrikos'' have been found to regulate algal blooms as they feed on toxic dinoflagellates. However, there is also some data available on Polykrikos being toxic to fish. History of knowledge ''Polykrikos'' was first seen in 1868 by Uljanin and was mistakenly considered as a metazoan larva of a turbellarian flatworms. In 1873 Butschili re-examined the specimen and concluded that the cell was an unusual ciliate, and Bergh later, in 1881, clarified ''Polykrikos'' dinoflagellate affinities. Morphology ''Polykrikos'' is a colony of zooids (units of a colonial organism) that carry out simultaneous functions of a whole cell. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus (biology)
Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. '' Panthera leo'' (lion) and '' Panthera onca'' (jaguar) are two species within the genus '' Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants of an ancestral taxon are grouped together (i.e. phylogenetic analysis should clearly demonstrate both monophyly and validity as a separate lineage). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synapomorphic
In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have evolved in their most recent common ancestor. ) In cladistics, synapomorphy implies homology. Examples of apomorphy are the presence of erect gait, fur, the evolution of three middle ear bones, and mammary glands in mammals but not in other vertebrate animals such as amphibians or reptiles, which have retained their ancestral traits of a sprawling gait and lack of fur. Thus, these derived traits are also synapomorphies of mammals in general as they are not shared by other vertebrate animals. Etymology The word —coined by German entomologist Willi Hennig—is derived from the Ancient Greek words (''sún''), meaning "with, together"; (''apó''), meaning "away from"; and (''morphḗ''), meaning "shape, form". Determining apom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endosymbiotic
An endosymbiont or endobiont is an organism that lives within the body or cells of another organism. Typically the two organisms are in a mutualistic relationship. Examples are nitrogen-fixing bacteria (called rhizobia), which live in the root nodules of legumes, single-cell algae inside reef-building corals, and bacterial endosymbionts that provide essential nutrients to insects. Endosymbiosis played key roles in the development of eukaryotes and plants. Roughly 2.2 billion years ago an archaeon absorbed a bacterium through phagocytosis, that eventually became the mitochondria that provide energy to almost all living eukaryotic cells. Approximately 1 billion years ago, some of those cells absorbed cyanobacteria that eventually became chloroplasts, organelles that produce energy from sunlight. Approximately 100 million years ago, a lineage of amoeba in the genus '' Paulinella'' independently engulfed a cyanobacterium that evolved to be functionally synonymous with traditiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Descent
Common descent is a concept in evolutionary biology applicable when one species is the ancestor of two or more species later in time. According to modern evolutionary biology, all living beings could be descendants of a unique ancestor commonly referred to as the last universal common ancestor (LUCA) of all life on Earth. Common descent is an effect of speciation, in which multiple species derive from a single ancestral population. The more recent the ancestral population two species have in common, the more closely they are related. The most recent common ancestor of all currently living organisms is the last universal ancestor, which lived about 3.9 billion years ago. The two earliest pieces of evidence for life on Earth are graphite found to be biogenic in 3.7 billion-year-old metasedimentary rocks discovered in western Greenland and microbial mat fossils found in 3.48 billion-year-old sandstone discovered in Western Australia. All currently living organisms on Earth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergent Evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is Cladogram#Homoplasies, homoplasy. The recurrent evolution of flight is a classic example, as flying pterygota, insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are ''analogous'', whereas ''homology (biology), homologous'' structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions. The opposite of convergence is divergent evolution, where related species evolve different trai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jellyfish
Jellyfish, also known as sea jellies or simply jellies, are the #Life cycle, medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals, although a few are anchored to the seabed by stalks rather than being motile. They are made of an umbrella-shaped main body made of mesoglea, known as the ''bell'', and a collection of trailing tentacles on the underside. Via pulsating contractions, the bell can provide propulsion for animal locomotion, locomotion through open water. The tentacles are armed with cnidocyte, stinging cells and may be used to capture prey or to defend against predators. Jellyfish have a complex biological life cycle, life cycle, and the medusa is normally the sexual phase, which produces planula larvae. These then disperse widely and enter a sedentary #Life cycle, polyp phase which may include asexual budding before reaching sexual maturity. Jellyfish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
