Search results
Results from the WOW.Com Content Network
The eggs have an average diameter of 1 millimetre (0.039 in). The eggs are generally surrounded by the extraembryonic membranes but do not develop a shell, hard or soft, around these membranes. Some fish have thick, leathery coats, especially if they must withstand physical force or desiccation. These type of eggs can also be very small and ...
A pregnant Southern platyfish. Pregnancy has been traditionally defined as the period of time eggs are incubated in the body after the egg-sperm union. [1] Although the term often refers to placental mammals, it has also been used in the titles of many international, peer-reviewed, scientific articles on fish.
Livebearers are fish that retain their eggs inside the body and give birth to live, free-swimming young. They are especially prized by aquarium owners. They are especially prized by aquarium owners. Among aquarium fish, livebearers are nearly all members of the family Poeciliidae and include: guppies , mollies , platies and swordtails .
The eggs have an average diameter of 1 millimetre (0.039 in). The eggs are generally surrounded by the extraembryonic membranes but do not develop a shell, hard or soft, around these membranes. Some fish have thick, leathery coats, especially if they must withstand physical force or desiccation. These type of eggs can also be very small and ...
Juvenile swordfish are far more vulnerable to predation, and are eaten by a wide range of predatory fish. [6] [23] Intensive fishery may be driving swordfishes and sharks into harder competition for reduced amounts of prey and therefore pitting them to fight more. [23] Human fishery is a major predator of swordfishes.
The mature eels then die, their eggs floating to the surface to hatch into very flat leaf-like larvae (called leptocephalus) that then drift along large oceanic currents back to New Zealand. [14] [17] This drifting is thought to take up to 15 months. [16] There have been no recorded captures of either the eggs or larvae of longfin eels. [14]
A single female may release 100,000 to 3 million eggs, but not all will be fertilized. The fertilized eggs become sticky and adhere to the bottom substrate upon contact. Eight to 15 days are needed for the embryos to mature into larval fish. During that time, they are dependent on their yolk sacs for nourishment.
This type of reproduction has been induced artificially in animal species that naturally reproduce through sex, including fish, amphibians, and mice. Normal egg cells form in the process of meiosis and are haploid , with half as many chromosomes as their mother's body cells.