How many ways do sharks reproduce? What are the characteristics of each?

There are three ways in which sharks reproduce

1.Oviparous: Generally adopted by large sharks. Shark eggs are large and nutritious. The discharged egg bundle is inside a flat cushion sheath, which is where the egg passes through the fallopian tubes.

The outer skin of the sheath hardens when it enters the water, and each corner of the sheath has a short, hollow horn from which seawater can enter, allowing the eggs to obtain oxygen. There is a limited number of ovulations at a time. The eggs are in the shape of a cloth bag or spiral, and after they are laid, they are fixed in coral reefs, seabed plants or rock crevices.

Washed. 2.Ovoviviparous.

Non-placental viviparity):

The fertilized egg develops in the uterus to form a yolk sac.

or eggs that are discharged from the ovaries into the uterus are nourishing** and do not form a placenta in the uterus. Whale.

It can produce more than 300 tails each time.

3.Viviparous (placental viviparity): Fertilized eggs with horny shells develop in the uterus, and the nutrients needed for growth are obtained from the yolk sac placenta until the young sharks are almost fully formed, giving birth to dozens of eggs at a time.

Most sharks in the ocean are viviparous. Most sharks breed seasonally each year, with some large sharks breeding every other year. Most sharks have a gestation period of 8-9 months, and the gestation period of the white horn shark can be as high as 24 months.

In general, large sharks produce more small sharks at a time, while small sharks do the opposite. Sharks also grow unusually slowly, not becoming sexually mature until they are 5-10 years old.

So in general, sharks are oviparous

Habits:1Entering the shack and sleepy food:

Sharks feed on injured marine mammals, fish, and carrion, culling weaker members of the animal.

In addition, some sharks also hunt a variety of marine mammals, fish, and animals such as turtles and crabs.

2.Camouflage: Great white sharks are not as agile as other sharks due to their large size.

But the great white shark is an excellent hunter because it can always surprise you.

Its upper body is dark, and its lower body is bright and bright, and they can use this protective color to sneak close to their prey.

3.Sleep: According to the Florida Museum of Natural History, whitetip sharks and tiger sharks actually sleep, sleeping during the day and moving out of the dust at night.

Sharks generally have three modes of reproduction, which are oviparous and ovoviviparous.

and viviparous. Oviparous are the most peculiar, and their size and shape vary from species to species. The largest egg is 30 cm, 14 cm wide and 9 cm high, making it the largest egg of a live fish.

The smallest eggs are 63 mm long and 37 mm wide. Most species have a rectangular shell with extended tendrils at the corners that are used to wrap the seaweed.

Stones and other objects are incubated. <>

Most shark fertilized eggs develop into fetuses in the mother's womb and eventually lay larvae. The number of fetuses produced varies from a few dozen to 2-3.

Close relationship with the fetus. The uterine wall of the mother shark and the yolk sac of the fetus.

The yolk sac placenta is formed, and nutrients and oxygen from the mother shark enter the fetus through the yolk sac placenta. <>

The lifespan of a shark varies from species to species. Most sharks have a lifespan of 20 to 30 years. White-spotted horn sharks can live for more than 100 years. Whale.

The lifespan may also exceed 100 years. Greenland sharks.

With a lifespan of 400 years, it is the longest-lived vertebrate known on Earth.

The main reason for their longevity is that this animal grows very slowly. It grows only about 1 cm per year, and reaches sexual maturity at the age of 150.

According to radiocarbon dating, the average age of a shark in Greenland is about 272 years, and the maximum lifespan must be more than 400 years. <>

When the bait is sufficient and the temperature and other ecological factors are suitable, freshwater sharks.

Growth is rapid, and body weight and length can increase exponentially. Growth is mainly influenced by temperature, feed, age and physiological conditions. The growth pattern is that juvenile fish grow faster in body length and gain weight more slowly.

When the body length increases to a certain length, the growth rate begins to slow down, while the weight increases rapidly. The data shows that during the suitable growing season from June to October, freshwater sharks generally grow at an average rate of more than 15 grams per day. Freshwater sharks that have been raised for 2 years can grow to more than 2 kilograms.

Sharks reproduce by spawning, and in this way they can reproduce offspring, and sharks are also very capable of reproduction.

The mode of reproduction of sharks is sexual reproduction, but the mating process of sharks is very complex, and sharks reproduce in the body.

Just like humans reproduce and then have children like humans, sharks are viviparous, and sharks are ferocious animals in the ocean.

There are three main methods of shark reproduction, which are oviparous, ovoviviparous, and viviparous, and sharks are fertilized in vivo.

Oviparous poly-initiation is a method used by large sharks, with a peculiar egg shell, which is laid by sharks, and most species have a rectangular egg shell with extended tendrils at the four corners, and the eggs will be wound around seaweed, stones, and other objects to hatch. Ovoviviparity is the development of a fertilized egg into a fetus in the mother's womb and finally laid. The viviparous type is when the fetus has a close connection with the mother, and the final birth is born.

Sharks belong to the subclass Plategill of the Vertebrate phylum Chondritalia, marine life, a few species enter freshwater, and are a group of medium to 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.

The current state of shark conservation

The shark is an ancient fish, and its fossils appear hundreds of millions of years before the dinosaurs, judging from the fragments of shark teeth and spines that have been excavated.

In this long history, sharks have disappeared through natural selection, and some species have disappeared and become extinct, but there are still some vulnerabilities of species in the more than 300 species that survive today, such as slow growth, late sexual maturity, and reproduction is also once every two years, and the reproduction rate is also very low.

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.

In 1999, three species of whale shark, basking shark (also known as elephant jiao) and man-eating shark were 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 wild animals.

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.