Search results
Results from the WOW.Com Content Network
Marine fish can produce high numbers of eggs which are often released into the open water column. 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 ...
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.
Adult fish also prey on fish eggs and larvae. For example, haddock were observed satiating themselves with herring eggs back in 1922. [14] Another study found cod in a herring spawning area with 20,000 herring eggs in their stomachs, and concluded that they could prey on half of the total egg production. [17] Fish also cannibalise their own eggs.
Females of the species can produce more eggs than any other known vertebrate, [6] up to 300 million at a time. [46] Sunfish eggs are released into the water and externally fertilized by sperm. [33] Newly hatched sunfish larvae are only 2.5 mm (3 ⁄ 32 in) long and weigh less than one gram.
Females frequently release two mucus-filled egg clusters, which can contain as many as 15,000 eggs. In total, they can lay up about 2 million eggs per year. [14] [17] All species are aposematic; they have conspicuous coloration with boldly contrasting stripes and wide fans of projecting spines, advertising their ability to defend themselves. [18]
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.
Large females can carry more eggs than small females, and between 1 million and 29 million eggs have been recorded. [3] The pelagic eggs measure 1.6–1.8 mm (1 ⁄ 16 – 5 ⁄ 64 in) in diameter and 2 + 1 ⁄ 2 days after fertilization, the embryonic development occurs.
These egg masses can include up to 180,000 eggs. [17] [23] For most species, the eggs drift on the surface. After two to five days, the fish hatch and the newly hatched alevin are between 0.8 and 1.6 mm (0.031 and 0.063 in) long.