Parthenogenesis has been reported only in one species of slug, but many species can self-fertilise.
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The plant is gynodioecious: individuals have either female flowers or what have been described as 'inconstant male' hemaphrodites. 'Inconstant males' can self- fertilise, but their seeds have less than 5% viability. Isolated female plants produce infertile fruits, or hybridise with other Muehlenbeckia species nearby. Fruits appear in October to June.
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Further conflicts arise because a hermaphroditic individual may not necessarily use received sperm; it may use another partner's, or self-fertilise. According to risk-averse models, when this is the case, it would be more prudent for an individual to invest in eggs.Leonard JL. Modern Portfolio Theory and the prudent hermaphrodite. Invertebrate Reproduction & Development. 1999;36(1-3):129-35.
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Like other tunicates, Ciona savignyi is a hermaphrodite. The male and female gonads do not ripen simultaneously so it does not normally self-fertilise. Gametes are released into the sea and after fertilisation, the eggs hatch into tadpole- like larvae. After a few days of development these attach themselves to a firm surface and undergo metamorphosis into juvenile tunicates.
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Their function may be to increase the population of the parasite to keep up with the growth of the host. Rhombogens contain hermaphroditic gonads developed within the axial cell. These gonads, more correctly termed infusorigens, self-fertilise to produce infusoriform larvae. These larvae possess a very distinctive morphology, swimming about with ciliated rings that resemble headlights.
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There are a few examples of fish that self-fertilise. The mangrove rivulus is an amphibious, simultaneous hermaphrodite, producing both eggs and spawn and having internal fertilisation. This mode of reproduction may be related to the fish's habit of spending long periods out of water in the mangrove forests it inhabits. Males are occasionally produced at temperatures below and can fertilise eggs that are then spawned by the female.
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Like other sponges, C. candelabrum draws water into its body through the small pores, filters out and ingests the nutritional particles, and expels the water through the oscula. It feeds on small particles under three micrometres in diameter, such as bacteria, unicellular algae and organic debris. The sea slug Berthella ocellata sometimes feeds on the sponge, rasping off fragments with its radula. This sponge is a hermaphrodite, but the male and female gametes mature at different times, so it does not self-fertilise.
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Many angiosperms (flowering plants) can self-fertilise for several generations and suffer little from inbreeding depression. This is very useful for species which disperse widely and can therefore find themselves growing in a novel environment with no conspecifics present. Polyploidy (having more than two paired sets of each chromosome), which is prevalent in angiosperms, ferns and a select few animal taxa, accounts for this. By having several copies of a chromosome, as opposed to two, homozygosity is less likely to occur in inbred offspring.
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Many aulopiforms are deep-sea fishes, with some species recognized as being hermaphrodites, some with the ability to self-fertilise. Some are benthic, but most are pelagic nekton. In general, aulopiform fish have a mixture of advanced and primitive characteristics relative to other teleost fish. A shortnose greeneye, Chlorophthalmus agassizi (Chlorophthalmoidei: Chlorophthalmidae) Aulopiforms have either a vestigial gas bladder, or lack it entirely, a hypaxialis muscle that is unusually extended to forward at its upper end and attaches to the neurocranium below the spine (perhaps to snap the upper part of the skull down when catching prey) and the position of the maxillary bone.
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