closely related but different species.

King Squid

Other names: Giant Squid, Giant Octopus, Giant Squid, King Squid, Ruler Squid

The largest squid in the world is the King Squid. They generally live in the depths of the ocean, rest in the deep sea during the day and swim to the shallow sea for food at night. Generally, the juvenile king squid is 3-5 meters long, and the adult king squid can be 17-18 meters long.

The king squid lives in the deep sea. There are legends of siren in the maritime civilization of many countries. They all look very similar to squid. Modern people also have some fragmented understanding of the king squid. When some seamen were on the night shift at sea, they once saw squid tentacles as long as more than 2 meters sweeping across the deck, and all the objects that could be caught were swept into the sea. The next day, people found iron drums bitten by rows of teeth hanging on the ship's side. During World War II, a destroyer weighing thousands of tons in the United States Navy suddenly found its speed slowed down during the night flight, but no fault was found. When people sent it to the dock for repair, they found that its propeller had been bitten through dozens of holes by sharp teeth. (Of course, this can only be a story, and no matter how powerful the sea monster is, it is impossible to bite through the rotating propeller.) Until today, when deep-sea diving is developed, people really took a real photo of the king squid.

since ancient times, there have been terrible stories about trolls in the sea among fishermen and sailors all over the world. According to legend, these sea monsters are often huge and grotesque, even with seven or nine heads. One of the most famous is the "Norwegian Sea Monster" described by Bishop Pompidan of Bergen in Norwegian Natural History in 1752. It is said that "its back, or the upper part of its body, looks like an island for about a mile and a half. ..... Later, a few shiny tips or horns appeared, sticking out of the water and reaching higher and higher. Some of them were as tall as the masts of medium-sized ships. These things were probably the arms of monsters, and it was said that the largest warships could be pulled down to the bottom of the sea.

since the 19th century, with the development of modern zoology, the absurd legend of sea monsters has gradually disappeared. However, there are still some reports that deserve our attention:

On November , 1861, the French warship "Aryton" was on its way from Cadiz, Spain, to Tenerife Island, when it met a sea monster that was only 5-6 meters long and had two meters long tentacles. Captain Ciel later wrote: I think that is the big octopus that has caused a lot of controversy and many people think it is fictional. Ciel and the crew put it in the middle with a harpoon, and put a rope around its tail. But the monster waved wildly and broke the harpoon and fled. Only a piece of meat weighing about 4 pounds was left on the rope.

On November 2, 1978, three fishermen in Newfoundland, Canada, found a huge marine animal stranded on the beach because of low tide. The fishermen said that it was 7 meters long, some horned hands were more than 11 meters long, and the sucker on the horned hands was 1 cm in diameter, with eyes as big as a face. Fishermen hooked it with hooks, and the monster struggled for a while and soon died.

Belgian zoologist Heifflmans collected and analyzed 587 reports of finding sea monsters from 1639 to 1966, and excluded 358 cases that might be wrong, deliberately deceptive and unclear, and found them credible.

He entered all the details in these reports into the computer for analysis, and got nine different sea monsters. Although there are still exaggerated elements in these reports, at least one of them has been confirmed by the sea troll that people thought was "impossible": the king squid.

In the 197s, there were several cases where the remains of the giant squid were washed ashore on the coast of Canada, and at least one of them was still alive. With the help of these entities, people finally learned something about the giant squid.

Squid King lives in the deep waters of the Pacific Ocean and the Atlantic Ocean. It is about 2 meters long and weighs about 2-3 tons. It is the largest invertebrate in the world. Its temperament is extremely fierce, it feeds on fish and invertebrates, and it can fight giant whales. There are often reports abroad that the king squid fights with the sperm whale. According to records, once people witnessed a king squid clinging to a sperm whale with its thick horn hand and sucker, and the sperm whale tried its best to bite the tail of the king squid. Two behemoths in the sea rolled violently, stirring up the turbid waves, and then both sank to the bottom of the water, and they did not know where to go. Most of this kind of struggle is that the sperm whale wins, but there have also been cases where the king squid pinches the whale's nostrils with his hands and suffocates the whale.

In this way, the sea monsters that people encountered in 1861 and 1878 mentioned above are definitely the king squid. How big is the biggest king squid? This question is difficult to answer. People once measured a squid with a length of 17.7 meters, and the diameter of the sucker on its horn hand was 9.5 cm. However, from the captured sperm whale, sucker scars with a diameter of more than 4 cm have been found.

Therefore, it is speculated that the king squid who fought with this whale may be more than 6 meters long. If there is such a big king squid, it is not far from the legendary Norwegian sea monster. However, such a big sucker scar may have been left by the sperm whale when it was young, and then it became bigger as the sperm whale grew up, so it is not certain that there is such a huge squid.

Sepia

, also known as cuttlefish and cuttlefish, is the most outstanding smoke expert among cephalopods.

Sepia officinalis, a kind of squid. Sepioidea) marine cephalopod mollusk, closely related to octopus and squid. Characterized by a thick calcareous inner shell (cuttlefish bone, cuttlefish bone or cuttlebone). There are about 1 species with a body length of 2.5? 9 cm (1? 35 inches), slightly flat, with narrow fleshy fins on both sides. * * * has 1 wrists, 8 short wrists, and two long wrists for predation, and can be retracted into two capsules; There is a sucker at the top of the wrist and the wrist. Living in shallow waters along tropical and temperate coasts, it often moves to deeper waters in winter. Common squid breeds in spring and summer, producing about 1? 3 eggs. Sepia species mainly eat crustaceans, small fish or eat each other. The main enemy is large aquatic animals. The meat is edible, the ink bag can be used to make ink, and the inner shell can be fed to caged birds to supplement calcium. The modern squid appeared in the Miocene 21 million years ago, and its ancestors were arrow stones.

commonly known as cuttlefish, the fishing catch is large, the meat is delicious and nutritious, which is the general name of sepiidae animals. Living in the warm ocean, swimming fast, mainly feeding on crustaceans, but also preying on fish and other mollusks. (There are giant squid, cuttlefish, cuttlefish (commonly known as squid), etc.) Common squid in China are cuttlefish and needleless squid.

[ Edit this paragraph] Taxonomic status

mollusca

Cephalopoda

Dibranchia

Decapoda.

◆ The front end of the head

is spherical, with a mouth at its top, an oral membrane around it and five pairs of wrists around it. There are a pair of developed eyes on both sides of the head, and the structure is complex. There is an oval pit under the back of the eye, called olfactory trap, which is the olfactory organ, equivalent to osphradium of Gastropoda, and is a chemoreceptor.

squid in the sea ◆ Foot

has been specialized into wrist and funnel. There are 1 wrists, which are symmetrically arranged left and right, with the first pair in the center of the back and 2-5 pairs to the ventral side in turn. The fourth pair of wrists is particularly long, and its end is tongue-shaped, which is called a tentacular arm. It can prey and contract into the wrist capsule. There are 4 rows of sucker with handle on the inner side of each wrist, and only 1 rows of small sucker on the inner side of the tongue-shaped part at the end of the wrist, which is called the tactile club. The middle sucker of the fifth wrist on the left side of the male degenerates, and it is specialized as the reproductive wrist or hectocotylized arms. It can transport sperm pods into the female body and play the role of mating device. According to the stem wrist, male and female can be distinguished.

On the ventral side of the funnel head, the base is wide and hidden in the lumen of the jacket, and there is an oval cartilage depression on both sides of its ventral surface, which is called an adhering groove. It is matched with the adhering ridge on the left and right sides of the ventral part of the mantle, such as a snap button, and is called an adhering apparatus, which can control the opening and closing of the mantle hole. The front end of the funnel is a simple water pipe, which is exposed outside the mantle. There is a tongue in the water pipe to prevent water from flowing backwards.

When the locking device is opened, the muscular cuff expands, and seawater flows into the cuff cavity from the cuff hole; Fasten the locking device, close the sleeve hole, the sleeve shrinks, and the pressurized water is sprayed from the water pipe of the funnel. This is the motive force of squid movement.

◆ The trunk

is bag-shaped, with a slightly flat back and abdomen, behind the head. The tunica with well-developed muscles outside is the visceral mass inside. There are fins on both sides of the trunk, which are separated at the end of the trunk and play a balance role in swimming. Because there are pigment cells under the skin on the back of the body, the skin can change the depth of color.

according to the living condition of squid in water, the head end is front, the trunk end is back, the side with funnel is abdomen, and the opposite side is back. However, according to the comparison between the mollusk system and the morphology of the squid, the front end should be ventral, because the foot gives way to the ventral side, the back end is the back, the back side is the front and the ventral side is the back, which is the morphological position of the squid, but the former positioning is often used for observation and narration.

[ Edit this paragraph] Structure and function

◆ The body wall

is composed of upper skin, muscles, etc., and has an endoskeleton. The epithelium is a single layer of cells, under which many chromatophore are flat, with elastic cell membranes and radial muscle fibers around them. Due to the contraction of muscle fibers, the pigment cells expand into a star shape, the muscle fibers relax, and the pigment cells return to their original state, which can change the depth of skin color. There is also an iridocyste under the epidermis, which makes the body surface shiny.

◆ endoskeleton

consists of an inner shell and cartilage. The inner shell is located in the shell capsule under the skin on the dorsal side of the body, which is very developed, with a long oval front end and a pointed protrusion at the end. The shell is calcareous, hard on the back, loose on the ventral side, with many gaps. The inner shell can not only increase the firmness of the body, but also reduce the specific gravity of the body, which is beneficial to swimming and helps to maintain balance. Cartilage is developed, and its structure is similar to that of vertebrates, but the cells have long branches. The main cartilage is cephalic cartilage, which surrounds the central nervous system and the balance capsule, and has holes on it, from which the nerves can extend. There are also cervical cartilage, wrist cartilage and so on.

◆ Digestive system

The digestive tube of squid is U-shaped. At the front of the mouth, in the center of the oral membrane, there is a muscular oral cavity, called mouth ball, which has a pair of parrot-beak-like jaws, one on the back and the other on the abdomen, which can chop up food. Mouth ball has a toothed tongue at the bottom to help swallow food. There are anterior and posterior salivary glands in the mouth. The pre-saliva is single, and the saliva tube opens on both sides of the tooth tongue, which can secrete mucus; A pair of posterior salivary glands, located at the back of the front end of esophagus, have a catheter leading to the entrance ball, which secretes venom and can kill and paralyze captured animals. Mouth ball is connected with a slender esophagus, which is connected with the hilum of the stomach. The stomach is located at the top of visceral sac, with a long saccular shape and a muscular wall. On the left side of the stomach is a blind sac with folded inner wall and cilia. The intestine is short and thick, turning from the pylorus of the stomach to the front, slightly arching, ending in the rectum, with the anus opening in the jacket cavity and behind the base of the funnel. There are a pair of anal valves on both sides of the anus, the function of which is unknown.

A pair of livers, very large, are yellow glands, occupying the first half of visceral sac and located on both sides of esophagus. The front end is round and the back end is pointed. A pair of hepatic ducts run backward along both sides of the intestine, and the latter two ducts meet and pass through the blind sac of human stomach. The gland branched on the hepatic duct is the pancreas. The liver can secrete enzymes and input them into the stomach for digestion. The hepatic duct contracts rhythmically and can absorb nutrients from the blind sac and stomach, so it has the function of storing nutrients. Pancreas secretes amylase and protease into the stomach. The digested food is absorbed in the blind sac, and the residue is excreted from the anus. At the end of the rectum near the anus, there is a catheter connected with a pear-shaped capsule, ink sac, which is located at the back end of the visceral mass. It is actually a very developed rectal blind sac. The gland in the capsule can secrete ink, which is discharged from the anus through the catheter, and the surrounding sea water becomes dark, so as to hide from the enemy, from which the name of squid comes.

◆ respiratory organs

a pair of pinnate gills, located on both sides of the front end of the outer lumen. Each gill has a gill axis with gill leaves on both sides, and the gill leaves are composed of many gill filaments. The gill is densely covered with microvessels, and water flows through the gill to complete gas exchange. There are gill glands on the back edge of gill axis, which are rich in blood vessels, which may be related to the nutrition of gill.

◆ circulatory system

the circulatory system of squid is basically closed tube, and there are still some blood sinuses. The heart consists of a ventricle and two auricles, which are located in the central pericardial cavity near the rear end of the body. The ventricle is rhombic, asymmetrical, with thick wall, long saccate atrial appendage and thin wall. An anterior aorta extends forward from the ventricle and branches to the head, tunica vaginalis, digestive tract, etc. A posterior aorta extends backward from the ventricle to the tunica vaginalis, rectum, gonad and other organs. Blood flows into the main vein through the microvascular network, and the main vein branches into a renal vein and enters the kidney; The renal vein and the external vein behind the body enter the branchia heart at the base of the gill (the wall of the branchial heart is spongy and can be contracted), enter the gill from the branchial vein, then enter the left and right auricles from the outlet branchial vein, and return to the ventricle. In blood circulation, metabolites are excreted in the kidney and oxygen-carbon exchange is carried out in the gills. Cephalopods have a very high blood pressure, which can exceed that of vertebrates.

◆ Excretion system

A pair of kidneys are saccular structures, including a dorsal chamber and two abdominal chambers. The ventricles are located on both sides of the back of rectum, and are symmetrical left and right. A pair of renal foramen are opened in the tunica cavity on both sides of the rectal end. The pericardial cavity extends into the abdominal cavity with a pair of catheters, and its opening is the renal orifice. The kidney can collect metabolites from the pericardial cavity. There are spongy vein glands around the vein of the kidney, and their branches are hollow and communicate with the vein. These glands have a layer of glandular epithelium with excretory function, which can absorb metabolites from the blood and discharge them into the renal capsule. The dorsal chamber of the kidney is located on the dorsal side of the abdominal chamber, and there is a hole communicating with the abdominal chamber. The excrement of squid does not contain uric acid but guanin.

◆ nervous system

the nervous system of squid is developed, which consists of central nervous system, peripheral nervous system and sympathetic nervous system. The structure is complicated.

The central nervous system is composed of three pairs of ganglia, including the cranial nerve ganglion, the visceral ganglion and the foot ganglion around the esophagus, surrounded by a cartilaginous shell. The dorsal side of esophagus is a pair of cranial nerve ganglia, and the ventral side is a pair of foot ganglia and a pair of visceral ganglia, which are arranged in front of each other. There is also a pair of carpal ganglia, which are located in the anterior part of the foot nerve and connected with it. A pair of mouth ball's ganglia are located in front of the brain. The peripheral nervous system consists of nerves extending from the central nervous system. The cranial nerve ganglion sends out the optic nerve and divides the olfactory nerve, etc. The visceral ganglion extends out of the sheath nerve, and its outer branches form a pair of stellate ganglion on both sides of the funnel base, and its inner branches branch out the cutaneous nerve and fin nerve. It also divides into infundibulum nerve, constrictor nerve, etc.

Two branches of sympathetic nerve branch from the back center of mouth ball's inferior ganglion, along the esophagus.