Do sharks have sperm?

All male sharks have claspers, extensions of their pelvic fins used to transfer sperm. Once inserted, the male expels sperm into the female along with seawater, and the eggs are fertilized inside the female's body. Some sharks are egg-laying, while others are live-bearing.

dlnr.hawaii.gov - Hawaiʻi Sharks | Mating and Reproduction - Hawaii.gov

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Mating and Reproduction

A shark’s existence revolves mostly around eating, avoiding being eaten, and making more sharks. Adult sharks get together to mate at specific times of the year. For female tiger sharks, that time comes once every three years. In Hawaii, mating occurs in January. Sperm is stored until ovulation takes place from May to July. Pups are then born 15-16 months later, peaking in September and October of the following year. Some other pelagic (open ocean) species, such as silkies, oceanic whitetips, and threshers, reproduce year round. Most coastal sharks give birth in the summer. It is thought that female sharks make it easy for the males to find them by giving out chemical signals, or pheromones, when they are ready to mate. Then the sharks engage in complex behavior as the male attempts to internally fertilize the female’s eggs. Often, the male must bite the female’s back, flanks and fins, sometimes inflicting serious looking wounds, in order to get into a position to mate. For this reason, some female sharks have skin nearly twice as thick as males. Near the end of this courtship ritual, the male usually bites the female’s pectoral fin, rolls on his side, and inserts a single clasper into her cloaca. All male sharks have claspers, extensions of their pelvic fins used to transfer sperm. Once inserted, the male expels sperm into the female along with seawater, and the eggs are fertilized inside the female’s body. Some sharks are egg-laying, while others are live-bearing. Egg-laying sharks are known as oviparous, and the reproductive strategy is called ovipary. The only example in Hawaiian waters is the deep-water spongehead catshark. All other Hawaiian sharks give birth to live pups, but there are two variations on this approach, depending on what the developing embryos use as a food source. In some sharks there is a connection between the embryos and the uterine wall, so the young are nourished in a manner similar to that of placental mammals. This reproductive strategy is called placental vivipary. In most live-bearing sharks there is no connection between the embryo and the uterus. The young get their nutrition from a yolk sac. This strategy is called aplacental vivipary. In some sharks, particularly the lamnids (threshers, makos, whites, and others), things can get very interesting once the yolk sac is used up. The developing pups may eat unfertilized eggs released by the mother to feed them. Threshers and a few other species even eat younger embryos, their own siblings, in what is sometimes known as “intrauterine cannibalism.” It’s not known how long it takes a spongehead catshark’s eggs to hatch. The eggs of most oviparous sharks hatch in about six to 12 months, but it’s 27 months for the brown catshark, another deep-sea catshark. For live-bearing species, the gestation period ranges from nine to at least 22 months. Once born (or hatched), shark pups receive no parental care; they’re on their own. They emerge as small versions of their parents and start to feed immediately.

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How long are sharks pregnant?

12 months Shark pregnancy Sharks typically give birth after 11–12 months of pregnancy, but some, such as the frilled shark, are pregnant for more than three years. In some sharks, a placenta develops during pregnancy.

sydney.edu.au - The strange mechanics of pregnancy in one Australian shark

People tend to think of sharks as large, frightening predators with sharp teeth, so it might come as a surprise to learn that some shark babies grow in the same way as humans – attached to the mother by an umbilical cord and placenta. Our recent research published in the Journal of Comparative Physiology B sheds light on the placenta of the pint-sized Australian sharpnose shark – wherein a thin layer of egg capsule separates the mother’s and baby’s tissues.

Shark pregnancy

There are more than 500 different species of shark, some as small as your hand (like the dwarf lantern shark) and others as big as a bus (such as whale sharks). Reproduction in sharks is equally varied: some lay eggs, but most give birth to live young. Sharks typically give birth after 11–12 months of pregnancy, but some, such as the frilled shark, are pregnant for more than three years. In some sharks, a placenta develops during pregnancy. The placenta helps the baby shark breathe, eat and expel waste as it develops inside the mother. Other species of shark don’t have a placenta, and instead their babies feed on egg yolk, secretions, unfertilised eggs or even their own siblings. Biologists have long been fascinated by reproductive diversity in sharks, but haven’t yet figured out why some sharks have placentas and others don’t.

The Australian model for shark pregnancy

In Australia, we have a unique model to understand shark pregnancy: the Australian sharpnose shark (Rhizoprionodon taylori). This small shark is just 70 centimetres long, and lives off the coast of northern Australia.

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