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Pseudoplankton
Pseudoplanktonic organisms are those that attach themselves to planktonic organisms or other floating objects, such as drifting wood, buoyant shells of organisms such as ''Spirula'', or man-made flotsam. Examples include goose barnacles and the bryozoan '' Jellyella''. By themselves these animals cannot float, which contrasts them with true planktonic organisms, such as ''Velella'' and the Portuguese Man o' War The Portuguese man o' war (''Physalia physalis''), also known as the man-of-war, is a marine hydrozoan found in the Atlantic Ocean and the Indian Ocean. It is considered to be the same species as the Pacific man o' war or blue bottle, which is ..., which are buoyant. Pseudoplankton are often found in the guts of filtering zooplankters. References Biological oceanography {{ocean-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jellyella
''Jellyella'' is a genus of bryozoans in the family Membraniporidae. Etymology The genus is named in honour of the Eliza Catherine Jelly (1829–1914), of Cornwall, England in honour of her contributions to the study of bryozoans. Morphology ''Jellyella'' closely resemble ''Membranipora'', and in common with other members of the family Membraniporidae has twinned ancestrular zooids. However, ''Jellyella'' can be distinguished by the presence of intricately branched processes (called spinules) projecting into the zooidal chambers. ''Jellyella'' also have a calcitic skeletal ultrastructure made up of transversely arranged, elongate spindles. Ecology ''Jellyella'' is unusual in being a pseudoplanktonic bryozoan found encrusting floating objects, both natural and artificial. ''Jellyella eburnea'' is common on shells of the squid ''Spirula'' (which become detached from the soft body of the squid after death) and on the shells of the planktonic gastropod ''Janthina''. ''Jellyella ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organism
In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fungi; or unicellular microorganisms such as protists, bacteria, and archaea. All types of organisms are capable of reproduction, growth and development, maintenance, and some degree of response to stimuli. Beetles, squids, tetrapods, mushrooms, and vascular plants are examples of multicellular organisms that differentiate specialized tissues and organs during development. A unicellular organism may be either a prokaryote or a eukaryote. Prokaryotes are represented by two separate domains – bacteria and archaea. Eukaryotic organisms are characterized by the presence of a membrane-bound cell nucleus and contain additional membrane-bound compartments called organelles (such as mitochondria in animals and plants ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planktonic
Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucial source of food to many small and large aquatic organisms, such as bivalves, fish and whales. Marine plankton include bacteria, archaea, algae, protozoa and drifting or floating animals that inhabit the saltwater of oceans and the brackish waters of estuaries. Freshwater plankton are similar to marine plankton, but are found in the freshwaters of lakes and rivers. Plankton are usually thought of as inhabiting water, but there are also airborne versions, the aeroplankton, that live part of their lives drifting in the atmosphere. These include plant spores, pollen and wind-scattered seeds, as well as microorganisms swept into the air from terrestrial dust storms and oceanic plankton swept into the air by sea spray. Though many planktonic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buoyant
Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the pressure at the bottom of a column of fluid is greater than at the top of the column. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object. The pressure difference results in a net upward force on the object. The magnitude of the force is proportional to the pressure difference, and (as explained by Archimedes' principle) is equivalent to the weight of the fluid that would otherwise occupy the submerged volume of the object, i.e. the Displacement (fluid), displaced fluid. For this reason, an object whose average density is greater than that of the fluid in which it is submerged tends to sink. If the object is less dense than the liquid, the force can keep the object afloat. This can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spirula
''Spirula spirula'' is a species of deep-water squid-like cephalopod mollusc, mollusk. It is the only extant taxon, extant member of the genus ''Spirula'', the Family (biology), family Spirulidae, and the order (biology), order Spirulida. Because of the shape of its internal shell, it is commonly known as the ram's horn squid or the little post horn squid. Because the live animal has a light-emitting organ, it is also sometimes known as the tail-light squid. Live specimens of this cephalopod are very rarely seen because it is a deep-ocean dweller. The small internal shell of the species is, however, quite a familiar object to many beachcombing, beachcombers. The shell of ''Spirula'' is extremely light in weight, very buoyant, and surprisingly durable; it very commonly floats ashore onto tropical beaches (and sometimes even temperate beaches) all over the world. This seashell is known to Conchology, shell collectors as the ram's horn shell or simply as ''Spirula''. Description ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flotsam
In maritime law, flotsam'','' jetsam'','' lagan'','' and derelict are specific kinds of shipwreck. The words have specific nautical meanings, with legal consequences in the law of admiralty and marine salvage. A shipwreck is defined as the remains of a ship that has been wrecked—a destroyed ship at sea, whether it has sunk or is floating on the surface of the water. Overview A wreck is categorized as property belonging to no apparent owner that either sinks to the seabed or floats on the surface of the water, whether it be intentionally cast overboard or as the result of an accident. The term encompasses the hull of the vessel and its fixtures as well as any other form of object on board, such as cargo and stores, and personal effects of the crew and passengers. This also encompasses the narrower definition of salvage, that is, property that has been recovered from a wreckage, or the recovery of the ship itself. There are a number of factors that contribute to the formation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Goose Barnacle
Goose barnacles, also called stalked barnacles or gooseneck barnacles, are filter-feeding crustaceans that live attached to hard surfaces of rocks and flotsam in the ocean intertidal zone. Goose barnacles formerly made up the taxonomic order Pedunculata, but research has resulted in the classification of stalked barnacles within multiple orders of the infraclass Thoracica. Biology Some species of goose barnacles such as ''Lepas anatifera'' are pelagic and are most frequently found on tidewrack on oceanic coasts. Unlike most other types of barnacles, intertidal goose barnacles (e.g. ''Pollicipes pollicipes'' and '' Pollicipes polymerus'') depend on water motion rather than the movement of their cirri for feeding, and are therefore found only on exposed or moderately exposed coasts. Spontaneous generation In the days before it was realised that birds migrate, it was thought that barnacle geese, ''Branta leucopsis'', developed from this crustacean through spontaneous gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buoyancy
Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the pressure at the bottom of a column of fluid is greater than at the top of the column. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object. The pressure difference results in a net upward force on the object. The magnitude of the force is proportional to the pressure difference, and (as explained by Archimedes' principle) is equivalent to the weight of the fluid that would otherwise occupy the submerged volume of the object, i.e. the displaced fluid. For this reason, an object whose average density is greater than that of the fluid in which it is submerged tends to sink. If the object is less dense than the liquid, the force can keep the object afloat. This can occur only in a no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Velella
''Velella'' is a monospecific genus of hydrozoa in the Porpitidae family. Its only known species is ''Velella velella'', a cosmopolitan free-floating hydrozoan that lives on the surface of the open ocean. It is commonly known by the names sea raft, by-the-wind sailor, purple sail, little sail, or simply ''Velella''. This small cnidarian is part of a specialised ocean surface community that includes the better-known cnidarian siphonophore, the Portuguese man o' war. Specialized predatory gastropod molluscs prey on these cnidarians. Such predators include nudibranchs (sea slugs) in the genus ''Glaucus''Gosliner, T.M. (1987). ''Nudibranchs of Southern Africa'' page 127, and purple snails in the genus ''Janthina''.Branch, G.M., Branch, M.L, Griffiths, C.L. and Beckley, L.E. (2010). ''Two Oceans: a guide to the marine life of southern Africa.'' Cape Town:Struik Nature. page 188. . Each apparent individual is a hydroid colony, and most are less than about 7 cm long. They are us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portuguese Man O' War
The Portuguese man o' war (''Physalia physalis''), also known as the man-of-war, is a marine hydrozoan found in the Atlantic Ocean and the Indian Ocean. It is considered to be the same species as the Pacific man o' war or blue bottle, which is found mainly in the Pacific Ocean. The Portuguese man o' war is the only species in the genus ''Physalia'', which in turn is the only genus in the family Physaliidae. The Portuguese man o' war is a conspicuous member of the neuston, the community of organisms that live at the ocean surface. It has numerous venomous microscopic nematocysts which deliver a painful sting powerful enough to kill fish, and has been known to occasionally kill humans. Although it superficially resembles a jellyfish, the Portuguese man o' war is in fact a siphonophore. Like all siphonophores, it is a colonial organism, made up of many smaller units called zooids. All zooids in a colony are genetically identical, but fulfill specialized functions such as feeding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zooplankton
Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by currents in the ocean, or by currents in seas, lakes or rivers. Zooplankton can be contrasted with phytoplankton, which are the plant component of the plankton community ("phyto" comes from the Greek word for ''plant''). Zooplankton are heterotrophic (other-feeding), whereas phytoplankton are autotrophic (self-feeding). This means zooplankton cannot manufacture their own food but must eat other plants or animals instead — in particular they eat phytoplankton. Zooplankton are generally larger than phytoplankton, most are microscopic, but some (such as jellyfish) are macroscopic and can be seen with the naked eye. Many protozoans (single-celled protists that prey on other microscopic life) are zooplankton, including zooflagellates, fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
