Goodeid
| Splitfins | |
|---|---|
| Redtail splitfin, Xenotoca eiseni | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Cyprinodontiformes |
| Family: |
Goodeidae D. S. Jordan, 1923 |
| Subfamilies | |
|
Empetrichthyinae |
|
Empetrichthyinae
Goodeinae
See text for genera and species.
Splitfins are a family, Goodeidae, of teleost fish endemic to Mexico and some areas of the United States. This family contains 40 species within 18 genera. The family is named after ichthyologist George Brown Goode.
The family is divided into two subfamilies, the Goodeinae and the Empetrichthyinae. The Goodeinae are endemic to shallow freshwater habitats in Mexico, particularly along the Mesa Central area, west of Mexico City, with some species found in brackish fringes at both the Atlantic and Pacific coasts. There are 36 species of Goodeinae in 16 genera. The Empetrichthyinae are typically found in the southwestern Great Basin of the United States, and contains 4 species in two genera.
The name "splitfin" comes from the fact that, in the male fish, the anterior rays of the anal fin are partly separated from rest of the fin. Splitfins can be up to 20 cm in length, though most species are much smaller, around 5 cm. Goodeid fish have internal fertilisation, with males positioning themselves with a flexible part of the front anal fin, separated by a notch, which makes up the andropodium. Embryos hatch out of the egg within the ovarian follicle, and possess trophotaeniae, ribbon-like structures that emerge from the cloaca in front of the anal fin, on the ventral surface of the juvenile. These allow the absorption of nutrients within the ovary (matrotrophy), and are shed by juveniles shortly after birth. Female goodeids do not store sperm, and so a copulation event must precede each pregnancy.
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