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Most normal female fish have two ovaries. In some elasmobranchs, only the right ovary develops fully. In the primitive jawless fish, and some teleosts, there is only one ovary, formed by the fusion of the paired organs in the embryo. [2] Fish ovaries may be of three types: gymnovarian, secondary gymnovarian or cystovarian.
The surfperch, genus Embiotoca, is a saltwater fish with a gestation period of three to six months. [13] This lengthy period of pregnancy gives the family its scientific name from the Greek "embios" meaning "persistent" and "tokos" meaning "birth". The table below shows the gestation period and number of young born for some selected fish.
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 ...
In birds and mammals altricial species are those whose newly hatched or born young are relatively immobile, lack hair or down, are not able to obtain food on their own, and must be cared for by adults; closed eyes are common, though not ubiquitous. Altricial young are born helpless and require care for a length of time.
Ariidae males carry a clutch of a few dozen eggs in their mouths, [2] for about two months before they hatch. Luciocephalus pulcher; Jawfishes; Osteoglossid are all mouthbrooders. The parents can hold hundreds of eggs in their mouths. Once hatched, the young may make several trips outside the parent's mouth before deciding to leave permanently.
Fish born in different regions will show clear differences here. Studies of the commercial fishing industry in the United States show that the population of bluefin tuna in the North Atlantic is made up of fish hailing from both coasts. While the fish may live in close proximity out in the Atlantic, they return to their natal region to spawn.
The behavior of an amphibian hatchling, commonly referred to as a tadpole, is controlled by a few thousand neurons. [4] 99% of a Xenopus hatchling's first day after hatching is spent hanging from a thread of mucus secreted from near its mouth will eventually form; if it becomes detached from this thread, it will swim back and become reattached, usually within ten seconds. [4]
Each year the returning turtles dig between 6,000 and 15,000 nests, often returning to the same beach from where they hatched. Females usually mate every two to four years. Males on the other hand visit the breeding areas every year, attempting to mate. [76] Green sea turtles' mating is similar to other marine turtles.