Tuesday, May 28, 2019
Fishes :: essays research papers
thither are two classes of fishlike creatures in the Chordate Phylum. The first is Chondrichthyes Class, which comprises mainly of Sharks and Rays. The seconds is the common adenoidal fishes of the class Ostechithyes. The apparent similarities between each speech are only skin deep. They cod similar dapperly solely because of convergent evolution and non because of all(prenominal) close evolution connection. There paired fins squeeze out identify class Chrondrichthyes, which comprises namely of sharks and rays, their completely cartilaginous skeletons and biting jaws characteristic of the group. Chrondrichthyes are mainly carnivorous, and the sharks have highly adept senses for vision, olfaction, and hearing. They even posses a system of microscopic organs which can detect changes in water pressure around the shall. Sharks do not possess gills dither like a fish so a shark must continuously move in order to obtain luxuriant oxygen to survey. The large teeth of a shark are e volutionarily derived from jagged skin scales. Which are apparent on shark&8217s ancestor&8217s Placodermi class. The digestion system of a shark contains a &8220spiral valve intestinal system, which increases the surface area and lengthens the time food is digested in the unusually short gut system of a shark. Sharks sexually reproduce. Unlike a shark, rays have flattened bodies so they can hide themselves in the sand at the bottom of any shallow water area and wait for a meal. Rays also have a whiplike tail for defense and jaws, which it uses to crush mollusks and crustaceans. Class Osterrichhthyes has the most appropriate species of any vertebrate class. Unlike their oceanic cosines Bony fish have a skeleton made from calcium phosphate and a slimy skin covered by bony armorlike scales. Fish of the Osterrichhthyes class have gill flaps call an operculum. On the side of there head which have flaps that move while the fish is stationary drawing in water which the fish can convert into oxygen. An unusual characteristic of bony fish is that they can control their density and this control their buoyancy by means of a unique swim bladder. Fish system of flexible fins in another adaption the fish have made. Unlike sharks bony fishes fertile externally and even in the Osterrichhthyes Class there is great variation in reproductive techniques. There are two distinct subclasses of fishes, Ray finned and fleshy finned, each has a common ancestor. Though divergent evolution the ray finned fish have die a separate class from the fleshy finned.