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Fossilized egg cases that may have been laid by an elasmobranch or chimaeroid are known from as far back as the Devonian period. Egg sacs that can more confidently be referred to those taxa are known from the Carboniferous to Oligocene, although no embryos are known from these. [2] Shark eggs have been recognized in the fossil record.
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.
Fossil fish eggs have an extensive record going at least as far back as the Devonian and spanning into the Cenozoic era. The eggs of many different fish taxa have contributed to this record, including lobe-finned fish, placoderms, and sharks. Occasionally eggs are preserved still within the mother's body, or associated with fossil embryos.
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 ...
Fingerling – refers to a fish that has reached the stage where the fins can be extended and protective scales have covered the body. [4] At this stage, the fish is typically about the size of a human finger, [5] hence the name. Once reaching this stage, the fish can be considered a juvenile, and is usually active enough to move around a large ...
The Japanese name nigorobuna (ニゴロブナ) has been ascribed various etymologies. One has it that it earned the name ni-gorō-buna (Japanese: 似五郎鮒) meaning "gorō-buna's look-alike", because once it attains sizes of approximately 1.2–1.3 shaku (≈feet), it begins to look confusingly similar to the gengorō-buna (源五郎鮒) (C. cuvieri, the wild form of the Japanese crucian ...
While doing so they also release and fertilise their own eggs. The female cichlid will hastily attempt to scoop up her eggs and, in doing so, will also collect eggs from S. multipunctatus. These eggs will then hatch inside the unwilling adoptive mother's mouth, and proceed to eat the cichlid eggs present before being released by the cichlid.
The tetra is a tropical, silver metallic-colored fish, with red-tipped fins and a black marking on the dorsal fin. The tetra is a hardy community fish for beginners, and is optimal for the beginning fish hobbyist. [4] It is also relatively large for a tetra, growing up to 7.5 cm (3 inches). [4] They can live up to 5 or 6 years.