Reproduction of Scoliodon

Scoliodon, commonly known as spiny dogfish, is a species of shark found in the coastal waters of many countries. Like other sharks, Scoliodon reproduces sexually, with internal fertilization.

The male shark uses its pelvic fins, which are modified as reproductive organs called claspers, to transfer sperm into the female’s cloaca. The female shark then carries the fertilized eggs within her body until they hatch. This process is known as oviparity.

Table of Contents

The reproduction process is given below.

1. Copulation

Reproduction occurs almost throughout the year.
During copulation, the male twines around the female.
The male shark uses its pelvic fins, which are modified as reproductive organs called claspers.
Spermatozoa are transferred through the agency of grooved erected claspers of the male, one or both of which are inserted into the cloaca of females.

2. Fertilization

Fertilization is internal.
It takes place in the narrow anterior parts of the oviducts in front of the shell glands.

3. Development

Reproduction of Scoliodon | Dog fish — Fig: Reproduction of *Scoliodon*

Scoliodon are ovoviviparous.
Their eggs develop inside uteri so that they give birth to living young.
Depending upon the species 3 to 7 embryos may develop in each uterus.
The mucous lining of the uterus forms protective fluid-filled compartments, one for each embryo.
In the beginning, the gut of each embryo is connected by a tubular yolk stalk with a yolk sac containing yolk for nourishment.
When the yolk is exhausted, the yolk sac becomes shriveled and embedded in the uterine wall forming a yolk sac placenta.
When blood vessels develop, the tubular connection of the yolk stalk with the embryo disappears.
Instead, the embryo is attached to the uterine wall by a placental cord which gives off numerous slender tubular outgrowths, the appendicula.

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Reproduction of Scoliodon | Dog Fish