scholarly journals Reproductive adaptations to reduce locomotor costs in viviparous fish (Poeciliidae)

2017 ◽  
Author(s):  
Mike Fleuren
Keyword(s):  
Viviparous Fish ◽  
Locomotor Costs

Memoirs: Observation on the Breeding and Development of the viviparous fish, Heterandria formosa

1940 ◽  
Vol s2-81 (324) ◽  
pp. 479-520
Author(s):  
ELIZABETH A. FRASER ◽  
RACHEL M. RENTON
Keyword(s):  
Early Stage ◽  
Late Development ◽  
Head Region ◽  
Mature Ovum ◽  
Entire Area ◽  
Short Account ◽  
Viviparous Fish ◽  
Large Size ◽  
Noteworthy Feature ◽  
Heterandria Formosa

1. A short account is given of the breeding habits of Heterandria formosa in an aquarium. 2. The ovary and the mature ovum are briefly described, the noteworthy feature of the ripe ovum being the small quantity of yolk. 3. Degeneration of ova is found to be a common occurrence in unfertilized females, and to a less extent in those full of developing embryos. 4. The method for ensuring the fertilization of the egg within the follicle is portrayed. Over the area where the spermatozoa have entered the cells of the ovarian epithelium and those of the follicle form a solid plug which eventually disrupts to enable the fully developed embryo to escape into the cavity of the ovary. 5. It is characteristic of early development that the egg is encircled by a unilaminar ectoderm before there is any visible differentiation into endoderm and mesoderm. 6. Owing to the scarcity of yolk only a few periblast cells arise and no syncytial layer is formed. 7. The primitive-germ cells are visible at an early stage within the apparently undifferentiated mesendoderm cells. 8. A striking feature is the large size of the pericardium and its growth upwards as a pericardium hood which completely surrounds the head region of the embryo. Over the walls runs a network of blood-vessels from which the maternal capillaries become eventually separated by only an attenuated layer of protoplasm. Both respiration and nutrition are effected through the follicle. 9. A remarkable specialization is the development of a urinary bladder which expands into a thin-walled vesicle of enormous dimensions, finally occupying almost the entire area formerly filled by the pericardium and the yolk-granules. 10. The development of Heterandria is compared with that of other viviparous fishes. 11. The significance of the unusual features in early and late development is discussed and some comparisons are made with the conditions in higher vertebrates.

Sharply Angled Lateral Curvature Modification in Anal Fin of a Viviparous Fish, Xenotoca variata (Cyprinodontiformes: Goodeidae)

2020 ◽  
Vol 38 (1) ◽  
Author(s):  
Atsuo Iida ◽  
Risako Nakai ◽  
Jumpei Nomura ◽  
Rieko Tanaka ◽  
Nobutoshi Mizuno ◽  
...  
Keyword(s):  
Viviparous Fish ◽  
Lateral Curvature

scholarly journals Ecophysiological responses to the effect of annual management on an endemic viviparous fish in central plateau of Mexico

2013 ◽  
Vol 11 (1) ◽  
pp. 117-123 ◽  
Author(s):  
Fernando Garcia-Trejo ◽  
Silvia Laura Hurtado-Gonzalez ◽  
Genaro Soto-Zarazua ◽  
Oscar Alatorre-Jacome ◽  
Enrique Rico-Garcia ◽  
...  
Keyword(s):  
Hydrological Cycle ◽  
Central Plateau ◽  
Temperature Changes ◽  
Structure And Dynamics ◽  
Viviparous Fish ◽  
Ecophysiological Responses ◽  
The Subject ◽  
Biological Aspects ◽  
Population Structure And Dynamics ◽  
Meristic Data

Studies on the biological aspects of fish typically focus on species that currently have commercial value, causing species that lack such market value to be ignored. This is the case of several freshwater fish, specifically of several members of the Goodeidae family. In the State of Querétaro there are several species of this family characterized for being viviparous and having distinctive sexual dimorphism that may have commercial potential. The subject of this study is Girardinichthys multiradiatus, a viviparous fish endemic to the upper-half of the Lerma River basin. The lack of knowledge regarding its biology and ecology has prevented the development of guidelines to manage its habitat and to preserve its population. The objective was to determine the ecophysiological responses of G. multiradiatus to its environmental management. From the sampling (24 hours every two months) population structure and dynamics were analyzed throughout a hydrological cycle using meristic data (standard length). Trophic and ecophysiological responses to fluctuations in environmental factors were also identified. Although the mexcalpique is a polytrophic species, results show that it prefers feeding on Diptera or Cladocera, while detritus is the third substance frequently found in their stomachs. Environmentally, the water regime is responsible for fluctuations in the population dynamics of the species, while temperature changes are the most influence its energy balance. These results can guide efforts to conserve this species and its habitat.

Autotomy and running performance of fiddler crabs (Decapoda: Brachyura: Ocypodidae)

2019 ◽  
Vol 39 (5) ◽  
pp. 613-616
Author(s):  
Benjamin E Martin
Keyword(s):  
Recovery Time ◽  
Flat Surface ◽  
Fiddler Crab ◽  
Sexually Dimorphic ◽  
Fiddler Crabs ◽  
Running Performance ◽  
Sprint Speed ◽  
Negative Effect ◽  
Sprint Velocity ◽  
Locomotor Costs

Abstract The sexually dimorphic, enlarged major claw is a notorious trait among male fiddler crabs, but comes with potential locomotor costs. Possessing the ability to autotomize the enlarged claw is thus potentially advantageous to not only to escape a predator’s grip, but also to increase running performance. Previous studies concluded that autotomy either has no effect or even a negative effect on running performance. If the claw does not aid in locomotion, then shedding the enlarged claw that accounts for 40% of a fiddler crab’s mass should positively affect running performance. I therefore investigated autotomy and running performance in the Atlantic sand fiddler crab Leptuca pugilator (Bosc, 1801) with a focus on improving upon the methods of previous studies. Crabs were given substantial recovery time between collection, running trials, and autotomy induction. Maximum sprint speed was assessed by running crabs on a 1 m sand and mud track where individuals were significantly faster after autotomy of the enlarged claw (N = 64, t63=-7.25, P < 0.001). Intact running velocity was furthermore a significant predictor of autotomized running velocity (R2 = 0.194, P < 0.001). This study is the first to show a significant increase in fiddler crab sprint velocity after autotomy on a flat surface, and I propose where methodological pitfalls may have occurred in previous studies.

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