The process of sexual reproduction for cod involves the act of spawning, resulting in the egg and sperm coming together for fertilization in open water. The male and female swim as a pair in circles during the spawning process.
A female cod can release between 3 million to 9 million eggs during a spawning season. The larger the female, the more eggs she produces each season, which lasts from January through April. Cod mate in the open sea in frigid waters with depths up to 660 feet. Their eggs, however, are very buoyant and float to the water's surface, where they are left unattended.
The fertilized eggs hatch in eight to 23 days, and very small larvae form. The cod larvae reaches a length of approximately 4 millimeters. During the first week of life, a cod larva lacks a fully developed mouth and relies entirely on an attached yolk sac for nutrition. Guided movement is also limited for a cod larva until the second to third week of life when it is able to use its fins for propulsion. Male cod reach sexual maturity between the ages of 2 and 4 years, while females reach sexual maturity between 5 and 6 years of age.Learn More
Platyhelminthes, also known as flatworms, are hermaphrodites, meaning individuals of the species produce both sperm and eggs. These are released from the platyhelminthes where they become cross-fertilized by other platyhelminthes. Two types of platyhelminthes, trematoda and cestoda, lay eggs constantly. The turbellarian class has a seasonal cycle. Turbellaria also reproduce asexually by dividing. Turbellaria are the only class able to regenerate body parts.Full Answer >
Killer whales, like all other mammals, reproduce through sexual reproduction, which requires the union of a male killer whale's sperm with a female killer whale's egg. Once conception occurs, the fertilized egg develops into a young mammal that remains in its mother's uterus for approximately 17 months before being born.Full Answer >
The parts of an egg include the shell, the inner and outer membranes, the air cell, the albumen, the chalazae, the vitelline membrane, the yolk and the germinal disc. The shell is hard and porous and serves as a protective layer that allows gases to be transferred in and out of the egg.Full Answer >
Dolphins are marine mammals that give birth to live young following a gestation period of approximately 12 months. There are 40 species of dolphins, and they are all are part of the larger order of cetaceans, which includes all whales, dolphins and porpoises.Full Answer >