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Saturday, March 21, 2009
The Nautiloids are a group of marine animals of Phylum Mollusca in the subclass Nautiloidea, and are thus closely related to ammonites. Nautiloids were particularly abundant during the early Paleozoic era when they were primary predators and evolved a large diaversity of shell morphologies. More than 2,500 species of nautiloids are known from the fossil record, though extant nautiloids species are few in number. All extant cephalopods are believed descended from Paleozoic nautiloids.Three key shell features, internal chambers, the siphuncle and the sutures, are shared by all nautiloids. Thin walls between the internal chambers (i.e., camerae) of the shell are called septa. As the nautiloids grew, they would detach their bodies from the walls of the shell, slide forward, and secrete a new septum to the rear. Each new septum added a new camera in the shell. The body of the animal itself occupied only the last added chamber of the shell. The septa were perforated by the siphuncle, a tissue tube running through all of the internal chambers of the shell. Surrounding the were structures made of Aragonite, a polymorph of Calcium Carbonate that during fossilization was readily converted to Calcite. Nautiloids are considered to be a paraphyletic group united by shared primitive features absent in other cephalopods. They are believed to be ancestors of both ammonoids and coleoids, specifically, nautiloids of Order Bactritida, that descended from straight-shelled nautiloids of Order Orthocerida. The earliest Nautiloids in the fossil record are from the late Cambrian, Fengshan Formation in northeast China. These early forms appeared to have died out, leaving but a single family, the Ellesmeroceratidae that survived to the early Ordovician and gave rise to all subsequent cephalopods. Nautiloids apparently diversified during the Early and Middle Ordovician, possibly due to new ecological niches opened by the extinction of the predatory anomalocarids at the end of the Cambrian. Nautiloids remained diverse and widespread through the Ordovician, Silurian, and Devonian periods, exhibiting a wide variety of straight, curved and coiled shell morphologies. Nautiloids began to decline during the Devonian, possibly because of competition with their Ammonoids and Coleoids descendants and relatives the, with only Order Nautilida with tightly coiled shells apparently able to flourish. Nautilids were much less affected by the Permian-Triassic extinction event than the ammonoids. Nonetheless, only a single genus, Cenoceras, with a shell resembling the modern nautilus, survived the extinction event ending the Triassic Period. Nautiloids radiated again during the Mesozoic, as evidenced by 24 genera that are known from the Cretaceous, and were not as impacted by the extinction event at the end of the Cretaceous as the ammonoids which had no survivors. Three families and at least five genera of nautilids are known to have survived the extinction, enabling resurgence during the Paleocene, Eocene, and Miocene.Wednesday, March 18, 2009
Seahorse is fish type living in sea from gender hippocampus and set of relatives syngnathidae. The size varying between 16 mm (for species hippocamus denise) to 35 cm is detectable in middle and tropical water territory in the world. Sea-horse is the only its masculine species earns pregnancy. Dorsal fin at seahorse lays in underside while its pectoral fin lays in part of head at elbow gill. Some sea horse specieses is having colour transparant partly, so that not in evidence. Population of threatened seahorse because abundant arrest. Seahorse exploited at traditional herbologi at Tiongkok and 20 million seahorse have been catched every year. Imported seahorse export arranged in cities since 15 mays 2004
Vertebrate is creature in earth capable to run quickest, fastest swims is best and flies farthermost. These all because existence of framework made from hard material in their body. For example is bone which sturdy. Functioning bone as strong pop for tense muschels and lax, what does continuous movement passed articulation which hinged. Spineles animal of periopatetic back with lower speed compared to veterbrate. These because of body structure they which is bony not. Even is conceived of fish, cutting is including spineles of animal of back that isn't has bone in its body. But they have ability of extraordinary motion blessing of existence of a real unique system at its body. Cuttle slack body closed over by thick jacket layer. Below water inhalled and given of exit by strong muscles, causing makes it can go backward. Mechanism at very complicated cuttle.Tuesday, March 17, 2009
Sea surface temperatures give scientists information about ocean currents, climate, climate change and how a hurricane may evolve. Now, NASA has a web page that provides frequent updates on changing ocean temperatures. There are two primary types of sea surface temperature data that scientists use. The first is the actual temperature readings from the ocean water surface. The second is called a sea surface temperature anomaly that compares present temperatures to the long-term average. Visualizers at NASA's Scientific Visualization Studio at NASA's Goddard Space Flight Center, Greenbelt, Md. have created two products. The first is a daily update of actual sea surface temperatures. Whenever clouds in the satellite data block the sea surface, the product interpolates the data. Interpolation is a calculation method for estimating data in regions that fall between points of actual measurement. The second product is a 10-day average of sea surface temperatures over specific areas. This 10-day average helps to show or calculate the temperature anomaly. "Climate and weather are great dances between the oceans and the global atmosphere," says Bill Patzert, climatologist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Sea surface temperature changes control whether these dances are slow and graceful, as with climate, or stormy and violent, as with wild hurricanes and winter storms. Floods, droughts, hurricanes or balmy weather can often be foretold by shifting sea surface temperatures. Sea surface temperatures are a crystal ball that helps us see and plan for the future."
Deep sea fish is a term for fish that live below the photic zone of the ocean. Examples include the lantern fish, flashlight fish, cookie cutter shark, bristlemouths, anglerfish, and viperfish. Because the photic zone typically extends only a few hundred meters below the water, about 90% of the ocean volume is invisible to humans. The deep sea is also an extremely hostile environment, with pressures between 20 and 1,000 atmosphere (between 2 and 100 megapascal), temperatures between 3 and 10 degrees Celsius, and a lack of oxygen. Most fish that have evolved in this harsh environment are not capable of surviving in laboratory conditions, and attempts to keep them in captivity have led to their deaths. For this reason little is known about them, as there are limitations to the amount of fruitful research that can be carried out on a dead specimen and deep sea exploratory equipment is very expensive. As such, many species are known only to scientists and have therefore retained their scientific name.
The benthic and abyssal zones are where the cold, dark, deep waters of the ocean are found. These zones are the largest part of the ocean biome covering more than 80% of the vast ocean. The intertidal zone where the water meets land and the pelagic zone, or open ocean, make up a much smaller portion of the total area of the ocean, yet an abundance of ocean life is found in these zones because sunlight penetrates the water. To get an idea of how vast the ocean's depths are, consider that 79% of the entire volume of the earth's biosphere consists waters with depths greater than 1,000 m. Until recently, the deep sea was largely unexplored. But advances in deep sea submersion and image capturing and sampling technologies are increasing the opportunities for marine biologists to observe and uncover the mysteries of the deep ocean realm.
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