User:Ttbioclass/Ovalipes catharus

My project will cover the sexual cannibalism of Ovalipes catharus males towards females.

General Reproduction Information
Ovalipes catharus produces hundreds of thousands of eggs with carapace width and body mass affecting fecundity to a large degree. This paragraph will talk about the fecundity of the crabs, fertilization, larval release, life history, and general biology information. Some of the citations that are likely going to be used in this section are:

Mating Behaviors
Female Ovalipes catharus require large amounts of guarding from their male counterparts before and during mating due to their vulnerable states. This paragraph will talk about female molting for mating, male guarding, male carrying, and other mating behaviors. Some of the citations that are likely going to be used in this section are:

Sexual Cannibalism
Unlike in some other species, sexual cannibalism in Ovalipes catharus is not about mate choice. This paragraph will mainly talk about why the species performs sexual cannibalism, how they do it, how they choose whether to eat or mate, and some of the non-cannibalistic mating behaviors of the species. Some of the citations that are likely going to be used in this section are:

Mating and Reproduction
Ovalipes catharus reach sexual maturity within the first year of benthic life and females produce clutches of eggs from early spring to late summer. It is not known how many clutches can be fertilized from one insemination, but females have been observed to produce up to four or five without re-mating. In one clutch the female crabs produce between 82,000 to 683,000 eggs but like in other crabs a very large proportion of these are lost to disease or predation. Fecundity is also heavily influenced by carapace width and body mass, with larger and heavier crabs having higher fecundity. Larvae develop synchronously and are released in large numbers by vigorous waving of the female's body, which disturbs their egg cases and causes them to break out. Females mostly release their larvae at night and when releasing they stand on their dactyli before extending themselves as far as possible. They then angle themselves up and begin flexing their abdomen to release large clouds of larvae. Females have also been observed to preen the egg mass during development. Higher temperatures have been observed to prolong the breeding season, increase growth rates, and cause them to obtain sexual maturity sooner. This causes slight differences in mating times between populations of Ovalipes catharus living at different locations in the wild.

Mating Behaviors
Males and females meet in shallow sheltered bays during winter, which is July to August in New Zealand. The time is also variable between populations with some mating as early as May and some as late as November. In these shallow bays they mate when the females molt. Male crabs can only mate with soft post-molt females, so they begin to carry female crabs under their bodies up to 8 days prior to the females molting. Once the female has molted, she depends entirely on the male for protection, and he will even assist with the molting process by using his legs to remove parts of the female's old carapace. Once molting is complete they will mate for between 12-36 hours and even up to four days. After mating the female is released and the females move onto spawning grounds deeper in the water, of which the location is not known, and the males move to foraging grounds.

Sexual Cannibalism
Sexual cannibalism has been frequently observed in Ovalipes catharus, and it is directed by males towards females. This sexual cannibalism occurs when the female is soft-shelled after molting during the mating process. Male crabs protect the females they mate with from being cannibalized but unreceptive females or those that have mated with other crabs are in danger of being cannibalized. This is most likely done to maximize the number of eggs fertilized by his sperm. Some examples of males cannibalizing females they have mated with have also been observed. This sexual cannibalism is not about mate choice or adaptation and is instead more opportunistic. In one example male crabs that had not cannibalized female crabs all accepted frozen squid afterwards, while very few males that had cannibalized female crabs accepted frozen squid afterwards. This indicates that hunger could be a part of the cause behind the cannibalism, and male crabs just take the opportunity to feed while the females are vulnerable in their soft-shelled state. Unlike in other examples of sexual cannibalism, size was not shown to have an effect on whether cannibalism occurred. Sexual cannibalism in Ovalipes catharus is very prevalent with studies on the diet of the crab detecting it in almost every location tested. Part of the prevalence of Ovalipes catharus in its own diet could be due to males consuming each other during the breeding season, as the smaller males guarding females do not have protection themselves from cannibalism and can sometimes be mistaken for females.