In natural sea areas, seahorses usually like to live in the slow current of coral reefs. Because they are not good at swimming, they often use their tail, which is suitable for grasping, to tightly outline coral branches and seaweed leaves and fix their bodies so as not to be washed away by rapids. Most species of sea dragons grow at the junction of the estuary and the sea, so they can adapt to different concentrations of seawater and even survive in fresh water.
Seahorses and sea dragons have small mouths and are only suitable for feeding on live bait, while those who are not good at swimming can't prey quickly. Although they are deeply loved by marine aquarium lovers, this unique habit makes it difficult for them to survive in aquariums. Although shrimp, rotifer and fry are all suitable bait for them, how to make them feed fully is the key to the survival of hippocampus and sea dragon. During feeding, it is necessary to close the filtration system to create a calm and stagnant environment so that they can feed slowly and orderly. Another point is their life partners-if hippocampus, sea dragon and lively fish are kept together, then during feeding, Most of the live bait will be swallowed by those fish first ... Therefore, in order to successfully raise seahorses and sea dragons, according to my experience, it is best to keep them alone in a seaweed landscaping tank with gentle water flow and quiet environment. At the same time, Choose the small fishes with similar living habits, such as Aeoliscus Strigatus of Centriscidae and Monocentridae, and they will be good life partners for seahorses and sea dragons.
The male and female identification of seahorses and sea dragons is very simple, that is, the male fish has an abdominal sac (commonly known as a baby bag), while the female fish has no abdominal sac.
There is a small bag in the abdomen of male hippocampus, which can be used to hold small hippocampus. It can hold 2000 small hippocampus at a time. Pregnancy in hippocampus ranges from 10 to 25 days. Whenever the mating season comes, the tail of the male seahorse and the tail of the female seahorse will be intertwined, touching and poetic. More importantly, this mating action makes the female hippocampus eggs cleverly put into the male hippocampus' pouch, and the male hippocampus can also catch the eggs accurately. The "love" dance of hippocampus lasts about 8 hours. Before mating, the abdominal bag in the lower abdomen of the male hippocampus will swell and be ready to accept the eggs of the female hippocampus. The female hippocampus has a long oviposition tube, which can discharge eggs into the abdominal bag of the male hippocampus. After several weeks, these eggs will hatch into small seahorses, ready to be born. At this time, the male seahorse will hook a sturdy seaweed stem with its tail and constantly bend or stretch its body back and forth, especially when human women are in labor pains. At the same time, the mouth of their abdominal bags is slightly opened and gradually expanded. Subsequently, a little hippocampus spurted out from the opening, the male hippocampus kept convulsing, and the little hippocampus kept popping out of the abdominal bag. After the baby seahorse is born, the horse rises to the surface to inhale, so that the swim bladder in the body is filled with air. Each small hippocampus is about 1 cm long, and soon after birth, it began to feed on small creatures in the water by itself, and the male hippocampus was exhausted at this time.
The Latin scientific name of cetaceans is derived from the Greek word "sea monster", which shows the reverence of the ancients for this kind of giant living in the ocean. In fact, cetaceans vary greatly in size, ranging from a small body length of about 1 m to a maximum of more than 30 meters. Most of them live in the ocean, and only a few of them live in fresh water environment. Their bodies are very similar to those of fish, and they are streamlined and suitable for swimming, so they are commonly known as whales, but this similarity is just a convergence phenomenon in biological evolution. Because cetaceans have the characteristics of viviparous, lactation, constant temperature and breathing with lungs, they are exactly the same as fish, so they belong to mammals.
The cetaceans are characterized by constant body temperature, about 35.5℃. The skin is bare, with no body hair, only a few bristles on the snout, and no sweat glands and sebaceous glands. The fat under the skin is very thick, which can keep the body temperature and reduce the specific gravity of the body in water. The skull is developed, but the skull is small, the face is large, and the forehead bone and maxilla are significantly prolonged, forming a long snout. The neck is not obvious, the cervical vertebra is healed, and the head is directly connected with the trunk. The forelimbs are fin-shaped, the toes are not separated, there are no claws, and the joints of elbows and wrists cannot move flexibly, which is suitable for swimming in the water. The hind limbs are degenerated, but there are still remnants of pelvis and femur, showing residual bone fragments. The tail degenerates into a fin, and the skin at the end expands horizontally from left to right, forming a pair of large caudal lobes, which are not supported by bones. The spine gradually tapers in the long and narrow caudal trunk and finally disappears before entering the caudal fin. Unlike fish, the caudal fin can swing up and down and is the main organ of swimming. Some species also have dorsal fins to balance their bodies. Their bones have spongy tissues, and there is more fat in the body cavity, which can increase the volume of the body, reduce the proportion of the body and increase buoyancy.
Their eyes are very small, without lacrimal glands and transient membranes, and their eyesight is poor. There is no outer ear shell, and the external auditory canal is very thin, but the hearing is very sensitive, and it can feel ultrasonic waves, and rely on echolocation to find food, contact companions or escape from enemies. There are1-2 external nostrils, which are located on the top of the head, commonly known as jet holes. Generally, the closer the nostril position is, the higher the evolution degree is. Breathing with the lungs, there is a lung on the left and right, and there are many capillaries in it, which are elastic and can help the circulation of oxygen and adapt to the gas exchange on the water. You need to surface for air exchange every once in a while, and you can also dive for a long time. There are 20 pairs of ribs 10. The stomach is divided into four chambers. Most kidneys are tumor-shaped. The male's testicles are located in the abdominal cavity. Female animals give birth and breast-feed in water. The uterus is double-angled, with a pair of breasts, which are located in the cleavage on both sides of the reproductive fissure, and have slender nipples. The milk is rich in calcium, phosphorus and a lot of fat. The young have teeth during the embryonic period, but the teeth of whales are replaced by whiskers at birth, and the teeth of toothed whales are preserved for life.
The ancestors of cetaceans used to be animals that walked on all fours on land, probably herbivores or carnivores living mainly in coastal areas. Later, they were attracted by fish and other foods in the water, and after a long time, they returned to the ocean from land and gradually adapted to marine life. The earliest whales appeared in about 55 million? /FONT> 36 million years ago, the original whales in the middle Eocene, the original whales in the late Eocene, etc. Compared with the existing whales, their skulls are smaller, their nostrils are located in front of their heads, but they have not moved to the top of their heads. Their teeth are similar to those of ancient insectivorous and carnivorous teeth, with 44 or less teeth, and their teeth shapes and skulls are also very similar, with only a few differences, but they have adapted to living in seawater.
The baleen cetaceans are huge, and the smallest species is more than 6 meters long. There are no teeth in the mouth, only degenerated teeth can be seen during embryonic development, but there are150-400 comb-like horny whiskers on the left and right sides of the maxilla from the palate to the pharynx. The color, shape and number of whiskers vary with different species, which is one of the important basis for classification. There are two external nostrils, located on the top of the head, which can eject two water columns when breathing. The skull is extremely large, and some species can reach1/3 of the body length, which is symmetrical left and right. Cervical spine healing or separation. The sternum is small, only1-2 pairs of ribs are connected with the sternum, and the thorax is incomplete. No collarbone. The flippers generally have four fingers. There is a cecum in the digestive tract. They mainly feed on small crustaceans such as krill, and some species also eat small group fish, as well as benthic fish and shellfish. There are 3 families of baleen whales in the world, including Right Whale Family, Gray Whale Family and Fin Whale Family, with about 6 genera and 1 1 species.
The shape of toothed whales varies greatly, with the smallest species being only about 1 m and the largest being over 20 m. There are conical teeth in the mouth, but the shapes and numbers of different kinds of teeth are also very different. The least teeth are only 1 tooth, and the most are dozens, some of which are hidden in the gums and not exposed, so it is also one of the important basis for classification. There are only 1 external nostril, so only one jet of water can be ejected when breathing. The skull is asymmetrical left and right. There are five fingers on the flippers. The sternum is larger. No collarbone. No cecum. They mainly feed on squid and fish, and some can prey on large animals such as seabirds, seals and other whales. There are 8 families, about 34 genera and 72 species of toothed whales in the world, including pufferfish, physeteridae, swordfish, narwhalidae, Dolphinidae, Dolphinidae and Pilocetaceae.
Tuna, also called tuna, is a warm-water migratory fish in the ocean, mainly distributed in the low and middle latitudes, and widely distributed in the Pacific Ocean, Atlantic Ocean and Indian Ocean. The most similar to tuna is bonito, and the simplest way to distinguish it is that bonito has 4-6 black longitudinal bands in its abdomen, while other similar species, such as steering bonito and fox bonito, have dark longitudinal bands. Tuna, on the other hand, has no black spots or dark longitudinal stripes.
Tuna is spindle-shaped, torpedo-shaped, with strong muscles and crescent-shaped tail fins. The scales are degenerated into small round scales, which are suitable for fast swimming, with a maximum swimming speed of 20 meters per second. The fish is full of fat, and its cross section is slightly round. The main species of tuna are yellowfin tuna, bigeye tuna, albacore tuna and bonito, among which the first three are the main targets of longline fishing and the latter is the main target of pole fishing. Its spawning period is very long, and the spawning sea area is very wide, which makes tuna spawn in various sea areas all year round, and with strong fecundity, eaters all over the world can enjoy its delicious taste.
Because tuna must always swim fast to maintain its body supply, and it only moves in the depths of the sea, its meat is tender and delicious, and it is not polluted by the environment. It is a rare healthy food for modern people. Delicious and fresh tuna has always been one of the favorite seafood dishes in Japan and Taiwan Province, especially tuna sashimi, which is the best among sashimi. Not only the old diners get a deep taste, but even those who eat less sashimi will choose tuna sashimi to taste it in chunks.
The meat quality of tuna is very special, raw food is the best, and cooked food is also fragrant and delicious. The canned oil-soaked tuna is very delicious, commonly known as sea chicken, which is not only loved by people in Southeast Asia, but also by Europeans and Americans.
Tuna is a kind of fish with high nutritional value, which is deeply loved by consumers and has a vast market. Japan, Western Europe and the United States are the three major markets for tuna products. There is a great demand for tuna in Japan, with an annual consumption of 800,000-900,000 tons, accounting for about one third of the world's demand, especially fresh tuna, which accounts for 60% of the demand, and the annual import amount is about/kloc-0.00 billion US dollars. In today's reform and opening up, Chinese people are living better and better, eating more and more, and paying more and more attention to food and health care. They have lost their freshness for high-end seafood such as lobster, mussel and salmon. Therefore, I am now exploring the domestic market, and I will directly ship some tuna shipped to the Japanese market back to China for sale, so that Chinese people can enjoy this delicious and nutritious treasure in the sea at any time.
Tuna species
1, Yellowfin Tuna: The fish is spindle-shaped, slightly flat on the side, with a small head, a long and thin tail and pink flesh. The back of the body is blue-blue, the side is light gray, with a little yellow and a little horizontal belt. The second dorsal fin and anal fin of the adult fish and the small fin behind them are all bright yellow. The first dorsal fin and ventral fin are all yellow. Body length1-3m varies from sea area to sea area, and the weight is generally 40-60kg.
Yellow fin tuna has a wide range of feeding habits, mainly squid, surface fish and large crustaceans. As a long-distance migration, its migration is related to the seasonal change of current. In the tropical rainy season, it is far from the lighter coastal waters and swims to the high salinity sea area.
Yellow fin tuna is widely distributed in the equatorial waters of the three oceans and is a representative species in tropical waters. The common water depth of yellowfin tuna is160m, the water temperature is 20-28℃, and the maximum swimming speed is 90km/h..
Yellow fin tuna accounts for 35% of global tuna production. Most of them are used to make cans, and fresh and frozen products also continue to grow. Yellow fin tuna is now in a reasonable state of exploitation.
2. Bluefin Tuna is the largest species of tuna. A short, strong, slender body with tapered tail fins crossed; The color from the bottom to the side of the body is bright, the upper body is dark blue, the fin is dark, the small fin is yellowish, and the tail stalk ridge is black. The whole body is covered with scales, the mouth is quite large, the eyes are not big, the pectoral fin is short, and the end is less than the center of the first dorsal fin, which is the biggest feature of this species. The body length is generally1-3 meters, and the largest one is more than 3 meters long and weighs more than 700 kilograms.
Bluefin tuna usually fish in groups of 50-60, and there are fish schools with more than 1000. Habitat water layer from the surface to 50 meters deep, the most suitable water temperature10-20℃, the bait is mainly herring, sardines, mackerel, squid and crustaceans.
Average size: 200 ~ 400 kg
3. Bigeye Tuna, also known as fat tuna and paratuna, is about1.5-2.0 meters long, and the heavy tuna is above 100 kg, generally16-35 kg. The back of the body is blue-blue, and the side and abdomen are silvery white. The meat is pink and slightly soft. The pectoral fin is long, and its end is very sharp, reaching below the second dorsal fin, which is also narrow and close to the height of the first dorsal fin. The fish is gray, full of fat, short tail, and obviously larger head and eyes.
Big-eyed tuna inhabits deep water, which can reach 200-300 meters, and mature individuals inhabit the surface. Mainly feed on deep-sea fish, mainly small fish, squid and large crustaceans. The maximum swimming speed can reach 100 km/h.
At present, the catch yield of bigeye tuna is low, but the price is high, which has great development potential.
4. Longfin Tuna has a dark blue back, silvery white sides and ventral sides, and a uniform body color. Body length1-1.5 m, weight 15 kg. Large individuals can reach 45 kilograms. Pink flesh, knife-shaped pectoral fin, extremely long, longer than the head is the most remarkable feature of this species.
Albacore tuna is mainly distributed in the water layer of 90-150m in the daytime, sometimes as deep as150-200m, and in the near surface in the evening. The optimum temperature range of albacore tuna is14-20℃. The bait is mainly sardines and crustaceans.
The output of albacore tuna accounts for about 7% of the total tuna production, and most of it is used for canning.