Daphnia
The freshwater crustacean Daphnia reproduces by parthenogenesis in the spring to rapidly populate ponds, then switches to sexual reproduction as the intensity of competition and predation increases.
Queen Bee
An example of non-viable parthenogenesis is common among domesticated honey bees. The queen bee is the only fertile female in the hive; if she dies without the possibility for a viable replacement queen, it is not uncommon for the worker bees to lay eggs. Worker bees are unable to mate, and the unfertilized eggs produce only drones (males), which can only mate with a queen.
Sea Sponge
Asexual reproduction of sponges is through budding or fragmentation, when a small piece of sponge falls off of the main sponge and grows into a new one. Many freshwater sponges form small structures known as gemmules, which function as overwintering devices.
Fungus
The Ascomycota, commonly known as sac fungi or ascomycetes, form meiotic spores called ascospores, which are enclosed in a special sac-like structure called an ascus. This division includes morels, some mushrooms and truffles, as well as single-celled yeasts and many species that have only been observed undergoing asexual reproduction. Because the products of meiosis are retained within the sac-like ascus, several ascomyctes have been used for elucidating principles of genetics and heredity (e.g. Neurospora crassa).
Ascomycota
The reproduction of the Ascomycota is very varied and can be either asexual or sexual. The reproductive structures which are formed in the latter case, the elongated sac-like asci, are characteristic of the class. On the other hand asexual reproduction plays by far the greater role, and many species have given up the sexual process altogether.
Lizards
This asexual reproduction called parthenogenesis occurs in several species of gecko, and is particularly widespread in the teiids (especially Aspidocelis) and lacertids (Lacerta). Parthenogentic species are also suspected to occur among chameleons, agamids, xantusiids, and typhlopids.
Annelid
Depending upon the species, annelids can reproduce both sexually and asexually.
Asexual reproduction
Asexual reproduction by fission is a method used by some annelids and allows them to reproduce quickly. The posterior part of the body breaks off and forms a new individual. The position of the break is usually determined by an epidermal growth. Lumbriculus and Aulophorus, for example, are known to reproduce by the body breaking into such fragments. Many other taxa (such as most earthworms) cannot reproduce this way, though they have varying abilities to regrow amputated segments.
Sexual reproduction
Sexual reproduction allows a species to better adapt to its environment. Some annelida species are hermaphroditic, while others have distinct sexes.
Most polychaete worms have separate males and females and external fertilization. The earliest larval stage, which is lost in some groups, is a ciliated trochophore, similar to those found in other phyla. The animal then begins to develop its segments, one after another, until it reaches its adult size.
Cnidaria
Asexual reproduction via budding is common among cnidaria, particularly among the Hydrozoa class. Asexual larvae bud laterally from the adult polyps, which develop into polyps themselves. The budding is often incomplete, so that colonies of genetically identical polyps physically connected with each other can form.
