Friday, December 9, 2011

Cherax Quadricarinatus Aquatic Species

Cherax quadricarinatus is a large freshwater crayfish species (Parastacidae) native of north-west
Queensland and the Northern Territory of Australia. The species typically exhibits a gonochoristic sexual system, although in cultured populations various types of intersex individuals have been described as functional males. In the present study, the macroscopic morphology and the gonadal histology of one type of intersex are described and discussed. All intersexes having both pairs of genital openings (female and male openings) and lacking both appendix masculinae and red patches were functional females with normal ovaries and oviducts. From a histological  point of view, they did not differ from normal females having previtellogenic and/or vitellogenic ovaries according to size.

Cherax Quadricarinatus
Cherax Quadricarinatus
Cherax quadricarinatus is a large freshwater crayfish native of north-west Queensland and the Northern Territory of Australia which is intensively cultured  for economic purposes in Australia and many other countries in southern Asia, North and South America and  Africa. Although many biological aspects related  to the culture of C. Quadricarinatus have been studied,  including reproduction, growth and  nutrition, the sexual pattern of this species and its hormonal regulation is not fully understood.

Cherax Papuanus
Cherax Orange Papua
Cherax Albertisi
Cherax Quadricarinatus is considered a gonochoristic species with a bilaterally symmetrical reproductive system. In females, it consists of a pair of ovaries, oviducts and genital openings at the base of the third pereiopods,  while in males a pair of testes, vasa deferentia and genital openings at the base of the fifth pereiopods  are  observed. Cherax Quadricarinatus Males also present appendix masculinae at the base of the fifth pereiopods. An important male secondary sexual character is the soft red patch which is found on the outer surface of the propodus of the male claw giving to this species the common name of “red claw” crayfish. In this species, a variable proportion of several types of intersex animals can be found in which both male and female genital openings occur in different combinations. Morphological, biochemical and endocrinological studies of intersexes have  demonstrated that these individuals are functionally males with previtellogenic ovaries.
Cherax Sp. Blue Moon
According to some investigations done in our laboratory in which we observed some individuals having both pairsof genital openings being ovigerous “females” and hatching normal juveniles, we decided to carry out a macroscopic and histological analysis of the reproductive system of these intersex animals to achieve a better understanding of intersexuality in Cherax Quadricarinatus size, form and colour. Subsequently, they were quickly dissected and fixed in Bouin’s solution for 4h at  room temperature. Gonads were then sequentially passed through 90% ethanol for 20 min, 96% ethanol for 20 min, 96  %  ethanol-buthylic alcohol  (1:1  v/v)  for 30 min and buthylic alcohol for 30 min, and embedded in paraffin. Sections (5-6 μm thick) were stained with haematoxylin-eosin. At least three slides for each crayfish were inspected under light microscope.

Cherax Sp Papuanus, Cherax Papuanus, Cherax Sp Tiger, Cherax Tiger, Cherax Sp Asia Tiger
Cherax Asia Tiger, Cherax Sp Zebra, Cherax Zebra, Cherax Misolicus, Cherax Peknyi , Cherax Sp


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