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Fat is not present in the body of sharks, which are marine cartilaginous fish that breathe with gills.
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Gill. Sharks are fish that breathe with gills. Sharks belong to the subclass of vertebrate phylum Chondrothyla, plate-gill subclass, and a few species enter freshwater, which is a group of medium and large marine fish that swim fast.
The endoskeleton of the shark is composed entirely of cartilage, often calcified, but without any true bone tissue, the exoskeleton is not very developed or degenerate, the body is often covered with skin teeth (scales), the teeth are diverse, and there is hard muscle. <
1. Sharks are fish that breathe with gills. Sharks belong to the subclass of vertebrate Pyptimen chondritalia plate-gills, marine, a few species enter freshwater, and are a group of medium and large marine fish that swim fast. The endoskeleton of the shark is composed entirely of cartilage, often calcified, but without any true bone tissue, the exoskeleton is not very developed or degenerate, the body is often covered with skin teeth (qualitative scales), the teeth are diverse, and there is hard muscle, but the membranous bone never exists, and the brain is seamless.
The upper forehead is composed of palatal cartilage, and the lower forehead is composed of Mei's cartilage.
2. The indiscriminate fishing and killing of sharks by humans is the most important reason for the decline of shark populations. Human hunting is mainly used for both edible and medicinal purposes, and it is a symbol of wealth and status, and it is also extremely expensive.
Three species of whale sharks, basking sharks (also known as elephant Jiaoxiancha) and man-eating sharks have been listed in Appendix II of the International Convention on Endangered Species of Wild Fauna and Flora (CITES), and social activities are strictly prohibited. In 2001, the relevant departments of Guangdong Province listed whale sharks and basking sharks as key protected species of aquatic wildlife. The United States, Canada and other countries have implemented shark conservation programs.
Since 2004, more than 60 countries have banned the production of shark fins (fins), and Ecuador, a major exporter of shark fins, has also terminated the activity.
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Sharks use gills to breathe.
Sharks breathe with their gills. Sharks have five to seven gill cleft on each side, and oxygen is obtained by flowing in from the mouth and out of the gill slit as they swim. The shark's breathing action relies on the contraction of the gill muscles, which causes the opening and closing of the mouth, the dizzy expansion of the gill arch, and the contraction of the base bonds, so as to promote the entry and outflow of water.
The body of the shark is spindle-shaped, with cleft gills on both sides of the head, and it is a marine fish. Sharks under 80 percent are under length, and the vast majority of sharks are small fish, with the largest shark being the whale shark and the smallest being the broad-tailed little horn shark. Shark teeth evolved from shield scales and are composed of dentine, bone dentine and enamel.
The species of sharks are abundant, divided into eight orders and 25 families, there are about 250 to 300 species in the world, of which there are 130 species in China, and the more common sharks are great white sharks, red-tailed sharks, tiger sharks, rainbow sharks, etc.
Exterior features
The body is spindle-shaped, with cleft gills on both sides of the head, but resembles a common fish. With a few exceptions, the typical shark** is hard, dull gray in color, with tooth-like scales that make ** appear rough. tail strong and powerful, asymmetrical, upturned; Fins are pointed; The snout is appointed, anteriorly protruding, with a crescent-shaped mouth and triangular fangs under the snout.
Sharks have no swim bladder and need to swim constantly to avoid sinking to the bottom.
There are 80 species of sharks with less than the total body length, and the vast majority of sharks are small and intelligent fish. The largest shark is the whale shark, also known as the whale pattern, up to 20m, weighing 7000-8000kg, which can be described as the king of fish, the smallest is the broad-tailed small horn shark (also known as the small sperm shark), the mature male is 15cm, the female is 20cm, and the difference in size of different species of sharks can reach more than 100 times.
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1.It is a fish so it breathes with gills.
2.However, the hail does not have its swim bladder and cannot stay in any water layer, and the mountain needs to swim non-stop.
3.Although sharks breathe with gills, they are different from other fish.
4.Because most sharks are almost always swimming.
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Summary. Dear is happy to answer for you, dear, sharks breathe with gills. Sharks are fish, so it breathes with gills.
The gill is the main respiratory organ of sharks, located in the pharynx, and leads from the pharyngeal cavity to the outside of the body called the gill slit, the gill slit of bony fishes, which is protected by the gill cover on the outside. The anterior and posterior epidermis of the source fissure forms a number of horizontal wrinkled skirts called gill filaments, which are filled with microvessels.
Dear is happy to answer for you, dear, sharks breathe with a few fingers and gills. Sharks are fish, so it breathes with gills. The gill swim is the main respiratory organ of the shark, located in the pharynx, and is called the gill slit from the pharyngeal cavity to the outside of the tubular paddle, which is protected by the gill cover on the outside.
The anterior and posterior epidermis of the source fissure forms a number of horizontal wrinkled skirts called gill filaments, which are filled with microvessels.
Sharks are one of the overlords of the sea, and all of their organs have evolved to quickly catch prey in the ocean, they have sharp teeth, an old tail, and a perfect streamlining and camouflage color. However, such a powerful shark has no eyelids, no swim bladder can not float, and no seawater can be swallowed independently. The shark wheel fish does not have a swim bladder, so the physical strength stores a lot of fat to increase buoyancy, because it cannot float, so the shark must swim constantly to ensure that it does not sink.
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