There are over 400 different species of sharks. So, it’s no wonder that there are so many differences between the sharks from the way they look, how they hunt, and where they live. These differences extend to reproduction as well. Not all sharks reproduce the same way.
Do sharks lay eggs? Do they have live young? Let’s get started answering these questions.
There are three main ways in which sharks reproduce: viviparity, oviparity, and ovoviviparity. In some rare cases, there are sharks that can even reproduce through asexual reproduction.
The way in which a shark reproduces depends largely on their biology and where they live. A shark that is accustomed to the open ocean is more likely to produce live young. A shark that lives closer towards shore is more likely to produce eggs.
How Do Sharks Reproduce?
Reproductive Anatomy
A shark’s reproductive organs are surprisingly similar to that of many mammals.
The male shark reproductive organs are called “claspers”. It is long and can be found on the pelvic fin for the majority of shark species. In chimeras, the clasper is actually found on their head.
The females, on the other hand, have oviducts. The oviduct is basically a long tube that leads from the external portion of the female’s body to her womb.
To mate, the male will insert his clasper into the oviduct of the female where he will produce sperm to fertilize the eggs. Sharks don’t mount one another like in other animal species. Instead, the two sharks will swim parallel to each other during mating.
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How do Sharks Mate: Sharks Mating Habits
Unfortunately, we don’t know much about the habits of sharks when they mate. It is difficult to find and observe mating sharks in the wild, and most sharks will not reproduce while in captivity.
It takes several years, even decades, for a shark to reach sexual maturity depending on the species.
Researchers believe that most sharks will migrate towards open waters for the act of mating. However, most sharks will also lay their eggs in nurseries: shallow areas that are usually protected by the coast.
Researchers have also noticed that most females have bite marks on their bodies from their male counterparts. However, it’s not certain whether these bites are due to the male trying to mount them, or if they’re a product of the mating ritual.
It’s also known that sharks do not produce many young at one time. Many species of animals will produce a large number of young at once in the hopes that some of them will survive. Usually, because there are so many babies produced, they aren’t of the greatest quality.
Sharks, it seems, prefer quality over quantity. Instead of having numerous young at once, they will have about 2-100 young, depending on the species.
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Ways of Shark Reproduction
1. Viviparity
Viviparity refers to live birth. Over half of all cartilaginous fishes produce live young, and this is considered to be the most advanced form of reproduction. The reason that so many sharks produce their young this way is because they spend most of their time in the open ocean.
In order for sharks to be able to bear young, their bodies need to be able to support live young. They have gone through evolutionary developments so that the embryos can receive nutrients and are able to respirate while inside the reproductive tract.
They receive the nutrients and oxygen from an umbilical cord attached to the mother, much like mammals. The young will then live off the placenta until birth.
The difference between shark and mammal viviparity, though, is that juvenile sharks are independent immediately upon hatching. Most mother sharks do not even stick around long enough for the eggs to hatch. They simply find an ideal location for their eggs, lay them, and go on their way.
Viviparous sharks have small litters of pups, usually between 2-20- in total.
The eggs that these sharks produce are not buoyant, so they wouldn’t work in the open ocean where the adults primarily spend their time. Additionally, the absence of eggs allows the adults to dominate pelagic (open ocean) zones that they would not be able to if they laid eggs.
Many of these shark species are not able to produce a large number of eggs, either. So, instead, they simply produce live young. Researchers have found that live young born from sharks tends to produce a higher survival rate than those born in eggs.
Below are examples of common viviparous sharks:
- Blue Sharks
- Silvertip Sharks
Blue Sharks
Both male and female Blue Sharks will reach sexual maturity at about 4-6 years of age. When they are ready to mate, the male will bite the female to latch onto her. Researchers have noticed that females have developed skin three times as thick as the males, likely due to this ritual biting. The male will then insert his clasper into her to fertilize her.
As I stated above, Blue Shark pups grow inside of the mother. They derive their nutrients from a yolk sack. Once all the nutrients are depleted from the yolk sack, it is converted into a placenta from which the mother will provide them nutrients.
Gestation lasts for about 9-12 months after which the mother will produce a litter of 5-135 pups.
Silvertip Sharks
Female Silvertip Sharks reach sexual maturity when they reach 6.5 feet/2 meters in length. The males reach sexual maturity at 5.9 feet/1.8 meters.
When they are ready to mate, the male will hold onto the female. Many female sharks have been noticed with bite marks on their bodies because of this. Some have even been seen missing part of their dorsal fin.
Mating season occurs during the summer months, as does birth. The gestation period usually lasts for about one year, so the pups will be born in the summer, a year after they were conceived.
During gestation, the pups will feed on a yolk sack. Once the nutrients in the yolk sack are gone, the yolk sack modifies into a placenta from which the pups will feed.
When the mother is ready to give birth, she will do so in shallower waters. She will give birth to litters of 1-11 pups. It is most common for them to have 5-6 pups in each litter. When they are born, the pups are about 25-32 inches/63-81 centimeters long. The pups have sometimes been seen swimming with the mother for a short time before they go their own way.
Other viviparous sharks include:
- Blue Bull Sharks
- Hammerhead Sharks
- Lemon Sharks
- Mako Sharks
- Porbeagle Sharks
- Requiem Sharks
- Salmon Sharks
- Sandbar Sharks
- Sharpnose Sharks
- Sliteye Sharks
- Whale Sharks
- White Tip Reef Sharks
- Whitecheek Sharks
- Whitenose Sharks
2. Oviparity
Oviparity refers to the laying of eggs, and is the most common form of reproduction amongst fish. This form of reproduction takes place mostly in skates and chimera, and is actually less common in sharks. About 40 percent of all shark species will reproduce by oviparity.
The eggs, or the ova, will develop in the ovaries of the female and are developed with the help of hormones like progesterone and estrogen. The eggs that are produced are tough and leathery in texture.
Sharks are considered “true” oviparous, meaning that the eggs are fertilized in the womb before being laid. Gestation of the eggs can take anywhere from 6-9 months. How long gestation lasts depends on the species of shark and environmental factors like water temperature.
Gestation is not spent entirely in the mother shark. The eggs will usually stay inside the mother for several weeks before she lays it. After she lays the eggs, they are not fully developed yet. They will spend the rest of the gestation period in the water before they hatch.
The eggs are not just simply dispersed into the water column. Instead, the mother will spend a long time searching for the right place to lay her eggs. Oftentimes, they will choose to lay their eggs in nurseries with other sharks.
Many times, the eggs will have appendage-like attachments that adhere them to some kind of surface. The eggs may have horns, sticky mucus, or tendrils that help the egg stick to a surface. Even with this added protection, eggs are often eaten by predators.
A “mermaid’s purse”, for example, is often found on beaches. This is the egg sack of a skate or shark that has tendrils to help it stick somewhere. If you study pictures, you can even tell which egg cases belong to which species of shark based on its characteristics.
Eggs can often be seen sticking to rocky substrate, coral reefs, seaweed, or even the seabed. The egg will stay there until the embryo develops enough to hatch.
A major feature of oviparity is that each egg develops with a yolk inside. The yolk is absorbed by the embryo until it hatches so that the embryo can obtain the nutrients that it needs. When the embryo is ready to hatch, it will have developed into a miniature version of the adult shark.
The size of the eggs and the number of eggs laid depends on what species of shark we’re looking at. Some are much larger than others, and some species lay more eggs than others. Usually, sharks that reproduce by oviparity will produce between 10 and 200 eggs.
A really interesting thing about oviparity is that some female sharks have been documented giving birth without fertilization. Sharks like Bonnetheads, Blacktips, and Zebra Sharks have been known to produce eggs through “virgin births”, called Parthenogenesis.
Below are a couple of oviparous sharks:
- Bamboo Sharks
- Port Jackson Sharks
Port Jackson Sharks
Female Port Jackson Sharks will reach sexual maturity around 11-14 years of age. The males will reach sexual maturity at just 8-10 years of age. They will breed once a year.
Throughout most of the year, the males and females stay separate from each other. They will live in different habitats from each other, and they will only come together to breed. Mating occurs between July and August.
Researchers are not entirely sure about the whole mating process because it’s never been observed. Still, they’ve noticed that these sharks are more likely to spend time inside caves and ledges during the shark breeding season. They’ve also noticed that these sharks will stay at the bottom of the ocean floor for longer periods of time.
After fertilization, the female will produce egg cases between August and September. The egg cases are shaped like a spiral and are dark brown in coloration. She will lay 10-16 eggs which she will deposit in shallow reefs. The eggs will usually be seen between 16-100 feet/5-30 meters deep.
Female Port Jackson Sharks prefer coming to the same location every year to lay their eggs. When they produce the eggs, they will hide them inside the crevices of rocks to protect them from predators.
After breeding, the males will immediately head back into deeper water. The females will join them shortly after, once the eggs are laid.
The eggs will take about 10-12 months to develop before they hatch. When the pups hatch, they are about 10 inches/25 centimeters long. Unlike the adults, juveniles will usually live in bays and estuaries until they reach maturity.
Horn Sharks
When they are ready to mate, the male Horn Shark will chase the female. When they are both ready to mate, they will sink down to the ocean floor where the process will begin. The male will bite the female and wrap himself around her. The male will then insert his clasper into the female, and mating will last for about 30-40 minutes.
Horn Sharks begin mating between December and January. Because the females don’t hold onto the eggs throughout the gestation period, she will deposit the eggs just a few weeks after.
Interestingly, Horn Sharks don’t lay all of their eggs at once. Instead, they will lay two eggs at a time. They will lay two eggs once every 11-14 days and can deposit up to 24 eggs in total. The entire process can last between February and April.
When the female shark lays her eggs, she will do so in shallow water. She will hide the cone-shaped egg cases into the crevices of rocks to try and hide them from predators.
From there, it will take the eggs about 6-10 months to fully develop. How long it actually takes the eggs to develop depends on the temperature of the water.
When the pups hatch, they will be about 6-7 inches/15-17 centimeters long. They grow slowly, and they will not begin eating until about a month after they’ve hatched.
Other oviparous sharks include:
- Catshark
- Epaulette Sharks
- Necklace Carpet Sharks
- Bamboo Sharks
- Swell Sharks
- Zebra Sharks
3. Ovoviviparity
Ovoviviparity is a bit more complicated than the other two forms of reproduction. In fact, ovoviviparity is more like a cross between viviparity and oviparity. Sharks that reproduce through ovoviviparity reproduce by producing eggs. However, the young sharks will hatch from the eggs while still inside the mother.
This is similar to viparity, however, the mother does not produce a placenta like she does with viparity birth. Instead, the embryos will feed off the yolk sack that was contained inside their egg before they hatched. Although the mother does not have a placenta, she does provide her young with oxygen.
Sharks that produce eggs through oviparity will lay the eggs, and they will develop wherever the mother deposits them. In ovoviviparity, the mother carries the eggs inside of her body and they will develop there.
This way of producing and developing eggs is advantageous because it offers protection to the eggs. With oviparity, the eggs are often out in the open where they are vulnerable to predators. But, with ovoviviparity, the eggs are able to fully develop safely within the mother until they’re ready to hatch.
Unlike oviparity where the egg cases are tough, ovoviviparity produced eggs have a thin membrane that is easy to break out of. When the young is fully developed, the mother will then give birth to the pups. Ovoviviparous sharks will generally produce between 1 and 8 pups.
Sometimes, the pups aren’t even born right after they’ve hatched from their eggs. In some species, the pups will stay inside the uterus to feed on the eggs that are unfertilized. Eating unfertilized eggs is called “oophagy”.
In some species — like the Sand Tiger Shark — the pups will practice intrauterine cannibalism. This is when the pups that have hatched will prey on their siblings that have not hatched from their eggs yet. The first pup to hatch will do this to make sure that only the strongest pup survives.
Here are examples of ovoviviparous sharks:
- Nurse Sharks
- Tiger Sharks
Nurse Sharks
Male Nurse Sharks will become sexually mature around 10-15 years of age. The females will become sexually mature around 15-20 years of age. To mate, the male will bite the female to hold onto her while he inserts his clasper into her.
Nurse Sharks have a gestation period that lasts about 6 months, and she will give birth between June and July. These sharks will produce young about once every two years. After she has given birth to one clutch of pups, she is physically unable to reproduce for another 18 months.
When the female gives birth, she will usually have about 30 pups at once. However, the pups are cannibalistic. The larger and stronger pups will eat the smaller and weaker ones. Once it’s all done, there may be significantly less than 30 pups remaining.
At the time of birth, pups are about 12 inches/30 centimeters in length and are spotted. The spots will go away with age.
Tiger Sharks
Tiger sharks can migrate for thousands of miles/kilometers across the ocean every year. Because of this, it is very difficult for researchers to study them, so much of their reproductive habits is unknown. Unfortunately, researchers don’t yet know where female sharks go while they are pregnant.
Male Tiger Sharks will reach sexual maturity at 7.5 feet/2.3 meters. Females will reach sexual maturity at 8 feet/2.5 meters. To mate, the males will hold the female with his teeth while he inserts his clasper inside her.
Reproduction occurs between March and May, with births occurring between April and June of the following year.
Female Tiger Sharks will go through a gestation period of about 15 months. They will produce 10-80 pups who will be about 75 centimeters/29.5 inches long.
Other ovoviviparous sharks include:
- Cookiecutter Sharks
- Crocodile Sharks
- Greenland Sharks
- Gummy Sharks
- Great White Sharks
- Pacific Angel Sharks
- Pelagic Thresher Sharks
- Pygmy Sharks
- Sand Tiger Sharks
- Sawsharks
- Soupfin Sharks.
Asexual Reproduction
Although rare, sharks are sometimes capable of reproducing asexually. Reproducing asexually means that the female shark reproduces without the help of a male. She does this by creating a copy of herself that is identical or similar to herself genetically.
This form of reproduction in sharks is so rare that there are only a total of two documented cases where this has occurred. The only time that female sharks are likely to reproduce this way is when there are no other sharks around them in the wild. They may also reproduce this way when held in captivity.
The reason that this is not more common in sharks is because it’s an unideal way for them to reproduce. By limiting the young’s genetics solely to the mother, the species will be more limited genetically. If this occurs over enough generations, it could potentially lead to the development of diseases and mutations.
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Interesting Shark Reproduction Facts
Sharks are very complicated creatures. But, their reproductive processes make them even more interesting. Here are some interesting facts about shark reproduction that you probably didn’t know:
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Why Are Sharks Threatened?
Sharks face a lot of threats — primarily from humans. We hunt them for their meat, oil, and fins. They’re caught and killed accidentally in the bycatch of fishing for other fish. They’re affected by pollution, littering, and climate change.
Unfortunately, sharks are not able to bounce back from these threats very easily. This is due directly to their slow reproductive process.
Many species of sharks do not reproduce every year. Some will only reproduce every other year.
When they do reproduce, the pregnancies last for a long time, and few pups are born. For most sharks, gestation lasts between 9-12 months, but for some species, gestation can last for up to 31 months.
Depending on the species of shark, they may produce as few as two pups with each reproduction. The largest number of pups produced can be attributed to the Blue Shark which can have up to 135 sharks. That may seem like a lot, but even that isn’t enough.
When you think about fish, many species can lay millions of eggs at one time. Even still, we’re losing many fish species to the threat of overfishing. If fish can reproduce at much higher rates and still be in danger, imagine how the sharks are faring.
Now, assuming that the mother shark reproduces and bears young, it’s a slim chance that the babies will live to produce their own young. In many countries that hunt sharks, no distinction is made between young sharks and old. Unfortunately, many species of sharks take years to reach sexual maturity, so many wind up dead before they have a chance to reproduce.
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How Do Sharks Mate FAQs
1. Are Male Or Female Sharks More Aggressive?
There doesn’t seem to be a definitive answer as to whether male or female sharks are more aggressive. The general consensus is that females are usually more dominant than the males because they are larger in size. This doesn’t necessarily mean that they are more aggressive towards other species, though.
On the other hand, males can be quite aggressive with females during the mating process, leaving bite marks on their bodies. Researchers have even noticed that females will sometimes avoid males for this very reason.
2. Do Sharks Have Belly Buttons?
The short answer — yes, some sharks do have belly buttons. It might sound silly, but it’s true. Viviparous sharks — sharks that give birth to live young — are attached to a placenta while inside the mother’s womb.
Like mammals, this placental connection causes the formation of a belly button after the mother and offspring are no longer connected.
Unlike in humans where the belly button is clearly visible throughout the lifetime, a shark’s belly button will disappear in a few years. It doesn’t really look like a human belly button, either. Instead, it shows up as a scar between the pectoral fins.
3. How Many Babies Do Sharks Have At A Time?
The answer to this really depends on the species of shark. Sharks that are viviparous are more likely to have a smaller litter size than sharks that produce eggs. Still, most sharks will produce between 1-100 offspring.
Although some sharks will only have one or two babies, it doesn’t start out that way. They will have a significant amount of babies within their womb. As the eggs hatch, the larger pups will cannibalize the smaller ones until there is only one of two pups left.
