Sexing Stomatopods
Sexing Stomatopods
Sexing stomatopods is relatively easy if you can get a look at their ventral thorax - the segments with the three pairs of walking legs. Males are easiest because the pair of gonopods (penises) hang down from the last pair of walking legs. They usually are about a third as long as the leg and bend towards the midline. In some species they are colored which makes them even easier to see. However, in most species they are fairly clear. If you take the animal out of water and lay it on its back, the gonopods are relatively flacid and can be hard to see. Look at the inside base of the last pair of walking legs and you should be able to see them. When the males are sexually aroused, the gonopods become more erect, but that is usually pretty hard to see. The gonodpods form on juvenile males at a fairly early age. In a Gonodactylus at about 10 - 12 mm; in an Odontodactylus at around 30 mm.
Females have a pair of gonopores (vaginas)in a plate at the midline between the first pair of walking legs. The two holes have a "figure 8" appearence. I could see this in the photo of the female reared up against the side of the aquarium.
Females develop gonopores at a slightly larger size than when males develop gonopods - 18-20 mm for a female Gonodactylus; 35 - 40 mm for an Odontodactylus.
Color in some species can also help identify sex, but only in some and at times you can be fooled. In O. scyllarus, males have a generally green body while females are more olive or even brown (juveniles are yellowish). However, I have seen green females and brownish males. In G. ternatensis, males have blue antennal scales and uropods. They are yellow to orange in females.
Roy
