Headpiece
Certain headpiece
Headpiece or Cephalopoda is a well-organized class of invertebrates that is found only in the ocean. This category belongs to the association of mollusca. The number of known living tribes of this class is approximately 150. The well-known examples of this class are octopus, squid, and cuttlefish. The number of extinct creatures of Cephalopoda is higher than living ones. Many species of this class were found in palaeozoic and mesozoic times. Notable examples of the extinct creatures are Ammonite and Belemnite.
General compositions of cephalopoda are similar to those of other organisms of Molaska Union. Their visceral organs are long and covered with mantle. The secretion of the shell is caused by an incision. The middle and the middle of the armor is called the mantle cavity. The gills hang in this cave. There is a special type of rasping tongue or redula in the diet vessel.
Cephalopoda's head and legs are so approximate that the mouth is located in the middle of the feet. The free ends of the feet make many appendages (hands and tangents). Most living creatures have fins and shells. The shells of these creatures are either less developed or regenerated. The average size of the creatures of this class is quite large. The lineage called architeuthis is the largest living invertebrate. The total length of the specimen, called the princeps, of this lineage (including the tentacles) is 52 feet. Cephalopoda is eaten exclusively by whales, crustacea and some fish.
External body and general organization
nautiloids and ammonites probably lived near the sea in shallow water. To protect her, calcium shell was on top of her body. The speed of their movement was probably negligible. All these possibilities are found in the life of the present nautilus. Diibranchia is a sharp swim in contrast. Some of the main characteristics of their external organization are as follows. Internal body
All cephalopoda covers the inner cartilage above the main ganglion of the nervous system. This diaphragm in the dibracnia subclass has developed into a cortical structure. In this subclass, the skeletal base of the muscles in addition to karoti-like composition is also on wings, cervical, gill hands etc. They provide greater mobility to the creatures. Internal organ
In the dietary system of cephalopoda, the muscular cavity consists of a pair of jaws and karat jihwa, grasika, salivary gland, stomach, blindness, liver, and Andhra. The work of efficient chanting is done by powerful jaws and sandal jiva teeth. Satin jihwa is not in any cephalopoda. Nearly all the organisms of diabrancıca have a diverticulum of the intestinal near the rectum, in which a type of thick liquid called capsa (Sepia) or ink is segregated. Deep embarrassment is generated in water by its immersion by the creatures. This creates a defense against its enemy. Circulation and respiratory system
These systems are most developed in cephalopoda. Hematarsis flow through specific vessels. Circulation and oxygenation are particularly centralized in diabeticia. In it, there are two gills and two onions in place of four gills and four auricles, like nautilus. Water flow through the flow of contraction and proliferation of respiration in diabeticia, above the water flow. On the gill of Cephalopoda are like feathers. Renal organ
Nitrogen emission is excreted by renal. The liver, which also acts as an excretion in digestion along with digestion in other molasses, it only serves digestion. Nautilus has two kidneys and two in dibracnica. the nervous system
Cephalopoda's main follicle is located in the center and the follicles are very approximated. This kind of condensation is found in the central nerve. Cephalopoda's senses are eyes, Rhinophore or dirt limbs, balance belt (neural-control-limbs) and tantric compositions. Diabeticia's eyes are complex and functionally similar to the eyes of the vertebrae. Germic system
Sexism is found in Cephalopoda. Bisexual animals are not found in this category. Sexual dimorphism develops. In pelagic octopoda, males are much smaller than females. The male of cuttlefish is identified with a long tail similar to his wing. Approximately one or two pairs of almost all Cephalopoda males are converted into 'sex organ'. The male germ mechanism is more complex than the female. The male transfers the socrates into a tube-like composition or spermatophore. They are located in the special sacrosanct. These tubes are located near the mouth of the female, in nitils, sepia, loligo etc. or with the help of orphans, deposits are deposited in Parva cave, like in the octavat. The free end of an appendage of the octogenarian becomes transformed into a simple spoon-like composition and the ligam creates the limb. Different types of changes are found from Decapoda. These organs can be converted into one or more epigraphic organs. Color change and flame
In addition to the skin's permanent color, there is a cutaneous mechanism of contractile cells in diabeticia. These cells are called chromatophore. These cells contain pigment. The skin color changes temporarily by the spread and contraction of these cells.
In some decapoda, especially those found in deep water, light organ is found. These organs are found in various parts of the body, arm and head. Additions
Unlike other molasses, their seagation is limited to one end of the egg and the egg is found in the extraordinary language of all cephalopoda eggs. The development of the embryo is also at the same end. External skin is formed from one end of the chest. Later, a sheet of cells is formed under this outer skin. This sheet starts to be formed from the end of the outer skin, from which the anus is formed. After this, the cells going from the outer skin to the inside are produced from the mesoderm. It is noteworthy that the mouth is not surrounded by first hand rudiments. In the form of the outgrowth of the arm, the hand flows from the lateral and posterior end of the fundamental embryonic area. These angles continue to grow towards the mouth till they reach the mouth and surround it. The funnel is made from a pair of antioxidants. After making changes in cephalopoda, germlayers, there are different types of different organisms. During the addition, no lalval stage like other mollusca is found. Caste & Development
Due to short knowledge of the composition of soft organs of fossil cephalopoda, the claim of first incidence of the symbion in this class is based on the study of the shell. Thus, the two subclasses of this class are based on the composition of the gland of nautilus and the specifications of the intrinsic symptom, the division of diabrenaccia and tetrabranchia. This part has very little connection with the compositions of proton nitloid and ammonide. Similarly, the knowledge of the development of the Okopoda, which contains armor-absorbent and acaalcium, is a kind of solution in the absence of verifiable fossils.
It is necessary to mention the story of Nautilus's armor to know the history of the evolution of cellulosa released by geological records. Due to his general organization, he is the most primitive living photophobia. This armor is divided into several closed and horizontal chambers. The creature resides in the last cell. In this mechanism of cells, a central tube or siphon is found from the first chamber to the last cell. The first cephalopoda was found in the Cambrian rocks. In orthoceras, the nostalgia is found in the bracket shell and middle siphon; However this armor was straightened and not straightened. Later in the form of Nautilus, coiled armor was also found. Coiled armor has been found in Silurion Offidaseras (Ohidoceras). Similar armor has been found in the tricolor rocks with the current Nautilus shell. But the present Nautilus's armor was not found until the beginning of the tertiary period.
This brief outline indicates the first stage of the development of phalopoda. If we assume that Mollusca is a homogeneous group, then it would not be unreasonable to estimate that the origin of Cephalopoda was in Molasska. There was a similar shell of ordinary cap. Cephalopoda has been developed by which particular causes or methods, it is not clearly known. First of all, its longevity started due to limestone deposits on the head of a similar shaped shell. With each progressive increase, septum was released from the last part of the intersection. Thus there was fear of the formation of nautiloid armor. Gastropoda became horizontal for armor to avoid these losses. In present gastropoda, coiled armor is found only.
The modern squid, octangular and cuttlefish of the dibracineta subclass have internal and hearted armor. On this basis, they are differentiated from nautiloid. The amount of spirula in this fountain is such a creature that has partial external shell. The special condition of the diabrancaya armor is often due to the high growth of armor and the construction of secondary sheath around the armor. In the end, the other cover of this cover is larger than the armor. Due to the active swimming nature, the armor gradually disappeared and the outermost protective shell was replaced by the powerful prairie muscles. These types of muscles received special facility to swim animals. At the same time, due to the new orientation, there is also a need for reproduction of the gravitational center of the creatures because heavy and incomplete intersections are obstructing horizontal motion.
In the surviving octoblees, there is a special granularity of the armor. The shell is in the form of a microscopic cartilagenous stylet or feather base called 'cirreta'. These compositions are considered to be the remains of armor. Although it can not be said faithfully, it is the remains of the armor. Actually there is no definite information available for the ancestral tradition of this group. Distribution and natural history
All creatures of Cephalopoda are found only in the sea. There is no encouraging evidence to be found in the existence of these beings or in salt water. Although sometimes these tissues reach the estuaries, they can not tolerate low salinity.
As far as geographical distribution is concerned, some descendants and castes are found everywhere. A small creature called Cranchiascabra is found in the Atlantic, Indian and Pacific oceans. Common European octopus vulgaris and octopus macropus are also found in the Far East. Normally it can be said that the distribution of the tribes and castes is the same as in the larger sections of other sea creatures. Many Mediterranean tribes are found in the Southern Atlantic and Indopassic areas.
Small brittle crankshaasbra lives like plasques in adulthood i.e. it keeps moving around irregularly with the stream of water. Octopodas mainly crawl on the ocean floor or some float above the floor. Some species are found not only confined to the sea level but also in the middle depth. Although the total of octopodas are found mainly in shallow water but some are also found in very deep water.
There is a special effect on the delivery of these animals in the gene. Normal cuttle fish (Cepia officinalis- Sepia officinalis) come in shallow coastal waters for breeding in spring and summer. This type of migration is also found in other animals.
The method of coping of Cephalopoda is not particularly known. In relation to cepia, loligo, etc. it is said that their light organ performs gender demonstration. Sexual dimorphism is found on a regular basis.
Most cephalopoda eggs are given at coastal locations. These eggs are alone or in clusters. The method of laying eggs in pelagic organisms is almost unknown except some organisms.
Most cephalopoda are carnivores and survive mainly on crustacea. Small fish and other mollusca are also part of their diet. Some species of decapoda also eat small copepoda and pteropoda etc. Cephalopoda; Whales, porpoises, dolphins, etc. are eaten. Economic use
Cephalopoda is an important organism for humans. They are eaten by some species of humans. Cephalopoda is used as a fodder for catching fish in some parts of the world. Regularly nothing can be said about people eating these creatures, but they are eaten occasionally by most carnivores. An important item called cuttle bone was removed from Cephalopoda and was used by the primitive species for diseases of the leprosy and cardiac.
The first study of Cephalopoda was started by Aristotle. He focused his attention on this group. The study of modern morphology of Cephalopoda began from the time of Cuvier. Cuvier firstly named the group of these creatures as Cephalopoda.
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