CATDOLL : CATDOLL: What are the types of marine fish? How many ways do fish lay eggs?

1. Types of marine fish?

1. Sharks live in the ocean and are fish in the ocean. Sharks have existed on Earth 300 million years before the appearance of dinosaurs, which means they have existed for more than 500 million years. They have hardly changed in the past 100 million years.

2. Hairtail, belonging to the class of bony fishes, order of Perciformes, family of Hairtails, in the subphylum of Vertebrata under the phylum Chordata. It is mainly distributed in the western Pacific Ocean and the Indian Ocean, and in the Yellow Sea, East China Sea, Bohai Sea and even the South China Sea in China. It is known as one of the four major seafoods in China along with large yellow croaker, small yellow croaker and squid.

3. Grouper, inhabits coastal reefs, undulating and pebbly sea areas, coral reefs, shipwrecks or artificial reefs. Grouper is a typical predatory carnivorous fish. It relies on its sensitive vision and light and color perception ability to ferociously prey on fish, shrimp, crab, octopus, and even barnacles and other marine life. It especially likes to eat fresh animals. It is an endangered and precious species.

4. Cuttlefish, also known as squid, cuttlefish, eyefish, etc. It belongs to the phylum Mollusca, class Cephalopoda, order Decapoda, family Sepiidae. The "cuttlefish" or "squid" referred to in China mostly refers to the two species of Mansoni's needleless squid and golden squid, which are mainly produced in the East China Sea.

5. Flatfish are particularly suitable for bottom-dwelling life on the seabed. Because of their flat bodies, both eyes are on the side of the body facing upwards, and the color of this side matches the surrounding environment well; the side facing downwards is white. Flatfish have very fine scales on their body surface. Flatfish have only one dorsal fin, which extends almost from the head to the tail fin.

2. How many ways do fish lay eggs?

There are three types of fish reproduction: oviparous, ovoviviparous and viviparous.

1. Oviparity is the reproductive method of most fish. Fish lay eggs outside the body, and the embryonic development takes place outside the body. The embryonic development process completely relies on the nutrients in the eggs.

2. Ovoviviparous fertilized eggs develop in the female reproductive tract, mainly relying on yolk nutrition during development, and have no nutritional relationship with the mother, or the mother's reproductive tract mainly provides water and minerals, and finally the mother produces fry. Such as guppies.

3. The embryos of some viviparous elasmobranch fish are connected to the mother through blood circulation. The nutrients needed for embryonic development are not only provided by the yolk of the embryo itself, but also by the mother. There are some protrusions on the wall of the oviduct where the embryo develops, which are connected to the embryo, forming a structure similar to the placenta. The mother sends nutrients to the embryo through this structure. For example, the gray star shark.

3. What are the signs before fish spawn?

Before fish spawn, the signs vary for different fish.

Mainly, the color of the male fish will become brighter than that of the female fish (nuptial color). When the female fish reaches sexual maturity, her abdomen will be more swollen, and the male fish will constantly chase the female fish.

The reproduction method of oviparous fish is: the male and female broodstock ovulate and fertilize at the same time, and the eggs are fertilized in the water. The vast majority of fish reproduce from oviparous offspring, but due to different species, their maturity, mating, spawning process, egg characteristics, etc. are also different. Even for the same fish, the maturity period varies greatly between different genera and species. Generally, small fish can mature in a few months and can reproduce once in 2-3 weeks or a few weeks; while large fish can mature in several years or more than ten years and reproduce once a year. For female fish to lay floating eggs, male fish will first spit foam to make a nest. Some male fish will gather grass to make a nest, and the fertilized eggs will hatch in the floating nest. Some fish eggs need to hatch in the starting drift of the water flow. For female fish to lay sticky eggs, the fertilized eggs need to adhere to water plants or other objects to hatch. The fertilized eggs of sinking eggs sink into the gaps between gravel to hatch. The spawning process and the time when fertilized eggs hatch fry also vary from species to species. Water temperature, light, water quality, dissolved oxygen content, etc. will also affect the hatching of fertilized eggs. If there are any deficiencies, the incubation period will be prolonged, the hatching rate will be reduced, and even deformed seedlings will be produced. Therefore, when artificially breeding these fish, it is necessary to understand their reproductive characteristics in advance and operate carefully. Female oviparous fish may carry a large number of eggs and lay a large number of eggs, but the number of fry obtained may be small, and some may even be far less than the number of eggs laid. Due to various reasons, the eggs laid by female fish are affected in three aspects: fertilization, hatching and survival of fry.

4. In what season do fish begin to spawn?

Fish usually spawn from March to May, with the largest number of eggs laid in late spring and early summer. There are some differences due to temperature differences. The temperature in the northern region is lower, so the ovulation time is later. The condition for spawning is that the water temperature reaches above 14 degrees Celsius, preferably 18-25 degrees Celsius.

Oviparous reproduction: refers to the reproduction of fish through external fertilization. When the fish reaches sexual maturity, the female fish releases eggs and the male fish releases sperm. When the eggs and sperm meet and combine in the water, the fertilization process is completed. After a period of time, these fertilized eggs will slowly develop and become small fish.

5. What are the types of fish in the Caspian Sea?

The Caspian Sea is extremely rich in fishery resources, with the Russian sturgeon, the white sturgeon, the Persian sturgeon, the European sturgeon, the Caspian salmon, the Caspian herring and other fish of the greatest economic value. There are six species of sturgeon in the Caspian Sea, including the Russian sturgeon, the naked belly sturgeon, the Persian sturgeon, the small sterlet sturgeon, the white sturgeon and the European sturgeon, and the eggs of these fish can be processed into delicious sturgeon caviar.

6. What are the types of fish in the Democratic Republic of Congo?

There are many species of Congo goldfish, which are tropical freshwater fish distributed in the Fwa Lake basin in the Democratic Republic of Congo in Africa. They can reach a body length of 3.9 cm and live in the bottom and middle layers of water. Their living habits are unknown.

The Congo River Basin has the wettest and hottest climate in Africa, and the most extensive and densest equatorial rainforest. The Congo River has a continuous supply of rainwater all year round, and the flow is balanced, so there are many types of goldfish.

7. What is the reason for the prosperity of fish species?

“The sea is wide enough for fish to leap, and the sky is high enough for birds to fly.” The sky is the territory of birds, and the water is the world of fish. Why can fish dominate and thrive in the vast ocean and lakes? Because nature has endowed them with the ability to live in water.

Due to the influence of various environmental conditions in the water, fish have various appearances. But the fish that live the best and have the largest number have a spindle-shaped body. The streamlined spindle shape can greatly reduce the resistance when swimming in the water. The surface of a good body shape often has a layer of slippery liquid, which is the mucus secreted by the fish skin. This mucus is evenly applied to the fish scales, making the streamlined surface like a lubricant, reducing the friction between the fish body and the water during movement. There are multiple fins on the trunk of the fish, which are the fish's movement organs. There are paired pectoral fins and pelvic fins, as well as unpaired dorsal fins, anal fins and caudal fins. These fins are combined with muscle contraction and keep paddling, just like a propeller installed on the fish body, pushing the fish body forward continuously. Each fin has a division of labor. The pectoral fins and pelvic fins are responsible for the balance of the fish body and changing the direction of movement, while the caudal fin, anal fin and dorsal fin control the direction of movement and prevent the fish body from swaying left and right. The underwater world is not a peaceful world. Sometimes there are strong winds and surging waves; sometimes the temperature rises and falls, and the temperature is uncertain; sometimes there are "sneak attacks" and "robberies" from other species. Fish have their own instincts to deal with these. There is a special sensory organ on both sides of the fish's body. The sensory organ communicates with the outside world through the small holes on the scales. Many small holes on the scales are distributed along the sensory organ on both sides of the fish's body, arranged in a line. This line composed of the arrangement of scale holes is called the lateral line. Through this lateral line, fish can feel the direction of the water flow, the fluctuation of the water, the high and low water temperature and the sound waves in the water. Once the wind blows and the "water" moves, the lateral line immediately notifies the fish body, and the fish immediately prepares for emergencies.

Nature has given fish "18 martial arts", so it is no wonder that fish can be found in almost all waters around the world and grow and expand their ranks, making fish the largest family among vertebrates.

8. What kind of fish does salmon migrate to spawn?

Salmon, also known as salmon, is a species of salmon that lives in the Bering Sea area of ​​the North Pacific Ocean. During the migration season, several species of salmon, including Chinook salmon and Sockeye salmon, will enter the Yukon River in North America and swim upstream for more than 3,000 kilometers to the upper tributaries of the Yukon River at the border between the United States and Canada to spawn and reproduce.

9. What are the types and representative species of fish scales?

There are four basic types of fish scales. Most bony fish have bony scales that overlap and are arranged in a shingled pattern just below the epidermis. Sharks have scutes, tooth-like structures embedded in the skin that create a sandpaper-like surface. Coelacanths have four layers of tooth scales, while long-snouted scleractinians have diamond-shaped scales. Some fish, such as catfish, have no scales at all.

10. Which species does not belong to migratory fish?

There are more than 30,000 species of fish in the world, and except for migratory fish, all other fish do not migrate.

There are many migratory fish, such as hairtail, large yellow croaker, small yellow croaker, black carp, grass carp, silver carp, bighead carp, salmon, eel, etc. They have different ways of migration, some swim from one sea area to another, some swim from the ocean back to fresh water, and some swim from fresh water to the sea. The purpose of migration is also different, some are for reproduction, some are for finding food, and some are for wintering.