CATDOLL : CATDOLL: How do fish embryos develop? Discuss the process of fish embryo development?

1. How do fish embryos develop?

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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.

2. Discuss the embryonic development process of fish?

The embryonic development of fish can be divided into two periods: pre-embryonic development and post-embryonic development, with the period before and after the embryo hatches as the boundary. It is also called early development.

Pre-embryonic development takes place within the egg membrane, gradually developing from a fertilized egg into an active larva, and finally breaking the egg membrane to hatch. This period is often called hatching.

Post-embryonic development refers to the period from hatching to the ability to begin to ingest external nutrients or the differentiation of major organs.

1. Pre-embryonic development

It takes place inside the egg membrane and uses the yolk as nutrition.

Three major stages: cleavage stage, embryo formation stage, organ differentiation stage

(I) Temperature and incubation speed

Within the suitable temperature range, the lower the water temperature, the slower the development.

The four major fish species are sensitive to temperature changes around the blastopore closure period.

2. Hatching

Hypoxia often causes the embryo to hatch early, while increasing oxygen saturation inhibits hatching.

Within the range of normal oxygen content, the higher the oxygen content, the more normal embryos will hatch.

3. What is fish developmental biology?

Developmental biology is one of the important basic branches of biological sciences. Its research content is interpenetrating and interconnected with many other disciplines, especially genetics, cell biology, and molecular biology. It uses modern scientific technology and methods to study and analyze the processes and mechanisms of organisms at the molecular level, submicroscopic level, and cellular level.

A discipline that studies the mechanism of individual development using the methods of molecular biology and cell biology. It was developed from experimental embryology. Experimental embryology studies the relationship and properties of the various parts of the developing embryo, and how they affect each other. Developmental biology investigates the essence of this relationship, what substances (or substances) are at work, how the substances that work make embryonic cells differentiate in a certain direction, how the differentiating cells form tissues or organs to ensure the development of tissues and organs, how the normally developing embryo grows, matures, and becomes a growing individual, why the latter gradually ages after developing to a certain stage, and how to complete the entire development of the individual in a specified time and space sequence.

4. Summarize the types of fish fertilization, reproduction and development?

Fertilization in fish can be external or internal; reproduction can be oviparous, viviparous, or ovoviviparous.

Oviparous: fertilized and developed outside the body. Some species are fertilized inside the body, but the fertilized eggs are hatched outside the body, so they are still oviparous, such as the medaka.

Ovoviviparous: Fertilization and hatching inside the body, the young fish are expelled from the mother as lively ones, but they do not use the mother's nutrition, so it is called ovoviviparous, such as guppy.

Pseudoviviparity: The oviduct of some cartilaginous fish has developed into a structure similar to the uterus of mammals, and is connected to the embryo by blood circulation through a "yolk placenta" structure, supplying nutrients for embryonic development.

The developmental stages of fish: embryonic stage - larvae stage - juvenile stage - young fish stage - adult stage - aging stage.

Development includes embryonic development and post-embryonic development.

5. What animal doesn’t look like a fish but is a fish?

The lancelet is known as the least fish-like fish.

Amphioxus, also known as Bai's lancelet, slug fish, double-pointed fish or sea hair, is a precious marine animal. Due to its extremely special morphological structure, it has the characteristics of both invertebrates and vertebrates. It is a typical representative of the transitional type from invertebrates to vertebrates. Therefore, it is highly valued by the biological community at home and abroad.

The appearance of lancelet is very strange and interesting. It has a very small body, flattened on the left and right sides, pointed and thin ends, and a spindle-shaped body. It is generally only 4 to 5 cm long.

6. What type of fish is tilapia?

Tilapia - native to Africa, it is a tropical fish. The genus Tilapia includes more than 100 species, including subspecies. Tilapia has the characteristics of fast growth, high yield, omnivorous diet, few diseases and strong reproductive capacity.

7. Fish characteristics?

The shape, body temperature, bones and skin of fish are different from those of other animals. In addition, fish have an organ that other animals do not have - the swim bladder. The existence of the swim bladder is also the reason why fish can float in the water.

1. Shape

Fish have a variety of shapes, sometimes quite different, but in general most fish are elongated and streamlined. Generally speaking, fish that swim fast in the water have elongated bodies, while fish that swim slowly or live at the bottom of the water are relatively flat. But some fish have very strange shapes, such as seahorses. The smallest fish is less than 1 cm, and the largest fish (whale shark) can reach 18 meters.

2. Body temperature.

Fish are cold-blooded animals. The body temperature of some tunas and sharks (especially sharks of the family Carcharhinidae) is higher than the temperature of the surrounding environment. Bluefin tuna is the only warm-blooded fish.

3. Bones

The skeleton of a fish is made of cartilage (cartilaginous fish) or bone (bony fish). There are four to seven gills on both sides of the skull, of which the front one has evolved into the zygomatic bone. The spine of a fish is connected to the skull, the ribs in the chest are connected to the spine, and there are long spines extending from the spine on the back, tail and abdomen.

4. Skin

Fish have two layers of skin: the outer layer contains glands that secrete mucus, and the inner layer contains many connective tissues, scales and pigment cells. The outer layer of mucus helps fish reduce drag when swimming. Cartilaginous fish do not have mucus, but the tiny, tooth-like protrusions on their skin have a similar function.

5. Fish bladder

The swim bladder is an inflatable sac-like organ in the fish's body. Its main function is not breathing. Fish rely on the swim bladder to adjust their specific gravity. Fish can use the swim bladder to slowly rise or descend without moving. Most bony fish have a swim bladder, an organ for regulating buoyancy.

8. Cold-resistant fish?

All fish species in northern China are cold-resistant, such as the common carp, crucian carp, silver carp, bighead carp, grass carp, black carp, sturgeon, black carp, loach, yarrow, schizothorax and so on.

9. Marine fish?

A: There are many kinds of marine fish. Common ones include shark, yellow croaker, horseface fish, eel, ox tongue fish, Spanish mackerel, snapper, silver pomfret, turbot, hairtail, etc. These fish contain a lot of vitamins, collagen and unsaturated fatty acids, which are good for the body. Not only can they supplement nutrition, but they can also improve skin quality, and they are low in fat and will not make you fat.

10. Unpopular fish?

Freshwater perch is commonly known as perch, also known as flower perch. It tastes delicious, has few fine bones, tender and white meat, and basically has no fishy smell.

Eel is also called eel. It contains calcium, vitamin A and other nutrients.

Catfish is also called bearded fish. It is rich in protein and fat, with few bones, tender meat and rich flavor.

Bighead carp has a big and fat head.

Northeastern flatmouthed goby.

Stream flatnose goby.

Pseudohylidium trilineatum