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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.
Argulus foliaceus. Argulus foliaceus, also known as the common fish louse, is a species of fish lice in the family Argulidae. [1] It is "the most common and widespread native argulid in the Palaearctic" [2] and "one of the most widespread crustacean ectoparasites of freshwater fish in the world", considering its distribution and range of hosts. [3]
Corpora lutea are found only in mammals, and in some elasmobranch fish; in other species, the remnants of the follicle are quickly resorbed by the ovary. [2] The ovary of teleosts is often contains a hollow, lymph-filled space which opens into the oviduct, and into which the eggs are shed. [2] Most normal female fish have two ovaries.
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 Minnesota DNR Division of Ecological Services received a State Wildlife Grant to conduct surveys for rare fish species in the Mississippi River from the Twin Cities to the Iowa border. These surveys were conducted from 2006 to 2008, and while the skipjack shad was a targeted species, none were found. [14]
The egg cell is generally asymmetric, having an animal pole (future ectoderm).It is covered with protective envelopes, with different layers. The first envelope – the one in contact with the membrane of the egg – is made of glycoproteins and is known as the vitelline membrane (zona pellucida in mammals).
Myxosporea is a class of microscopic animals, all of whom are parasites.They belong to the Myxozoa clade within Cnidaria.They have a complex life cycle that comprises vegetative forms in two hosts—one an aquatic invertebrate (generally an annelid but sometimes a bryozoan) and the other an ectothermic vertebrate, usually a fish.
This two-year reproductive cycle usually occurs in lemon sharks, sandbar sharks, and nurse sharks. [22] One hypothesis states that females can engage in polyandry to find genetically dissimilar and therefore compatible males to produce high quality offspring. [20] However, no concrete evidence has been found to strongly support this hypothesis.