Recopilation of Asexual animals Whose reproduction requires only one parent, and which has the result that the offspring are genetically identical to their progenitors because there is no fusion of gametes. That is, they are clones.
Here is a list of 20 animals that reproduce asexually:
Top 20 most impressive asexual animals
1- Marbled Crab
This type of crustaceans, which look like shrimp with fangs, are an asexual form of crayfish living in Florida and southern Georgia.
The mottled crab is an invasive species that has established populations in three countries at the same time greatly altering native wildlife. Many jurisdictions regulate the importation and release of various types of crayfish. In 2011, Missouri added the marbled crabs to its list of prohibited species.
Jasper crabs perform asexual reproduction through apomixis, a process normally reserved for plants in which an organism can generate an embryo without fertilization.
2- Whip tail lizard
Cnemidophorus of the family Teiidae . This type of lizard are only female. They usually perform a type of pseudocopulation where two females pretend to have sex as if it were a man.
Although not strictly necessary to reproduce, this simulated sex has been shown to increase the fertility of lizards in particular by acting in copulation and producing more eggs than those that do not.
The lizard that simulates the female role will produce eggs larger than the one that acts assuming the male role.
Although there is no external fertilization, the descendants of the lizards are not actually perfect clones of each other. Rather, recent research has shown that the New Mexico whip tail lizard produces twice as many chromosomes as other types of lizards.
"Partenogénesis", is the technical name for the reproduction of the whip tail lizards of New Mexico. It comes from the Greek"parthenos", meaning"virgin", and"genesis", meaning"birth." Parthenogenesis is the virgin development of the eggs, without previous fertilization.
3- Komodo Dragons
Varanus komodoendis . This type of lizard, the largest in the world, can reach a little more than 3 meters and has recently been shown that females can reproduce without being impregnated by a male.
This phenomenon was discovered in two dragons in captivity in two London zoo that they fertilized themselves being father and mother at the same time of their pups.
Of the eggs of this type of self-fertilization, only eggs with male genes go forward. This discovery is significant as the Komodo dragons are in danger of extinction and there are only 4000 left around the planet.
It can then be determined that by means of parthenogenesis, Komodo dragons can perpetuate their species, establishing an active population in which they can reproduce sexually and preserve the species.
4 - Sharks in captivity
Captive sharks, although only rarely, reproduce asexually. Hammer females caught as offspring and kept away from males in Florida, United States, were the first to reproduce asexually.
Asexual reproduction occurring in hammerhead sharks is also known as parthenogenesis. It refers to the female's ability to create and keep shark pups without a male shark and never mated.
This has only been observed in the cases of captive sharks, but can occur in nature where there is a serious shortage of male sharks. Although this phenomenon is extremely strange, asexual reproduction has been observed in several confined sharks.
Following the discovery of the puppy shark, extensive testing (including paternity testing) was performed. It was confirmed that some females had never had contact with any other shark, and the possibility of sperm retention from previous encounters was ruled out.
5- Hydra
The Hydra is a Cnidarian An exclusively freshwater body and there are many different species of Hydra. It is relatively small, with only a half centimeter in length on average.
The Hydra has a tubular body, a"head"at the distal end, and a"foot"at the proximal end. They use this foot to stick to the rocks or the bottom of the plants.
They have a ring of tentacles to collect food around their head. The Hydra has only ectoderm and endoderm (not mesoderm). Hydras usually reproduce asexually. Asexual reproduction of hydra usually occurs in environments with an excess of food.
The first step in the reproduction of asexual hydra is the beginning of the yolk, during this process, the first signs of an outbreak begin to show. Then the tentacles begin to grow and the mouth of the new hydra begin to develop. After separation of the new hydra begins, separation of the bud of the original hydra occurs.
Later the detachment of the New Hydra occurs. This is the final step in the reproduction cycle of asexual hydra, in this step the new hydra is released from the mother, creating a completely new hydra, this new hydra is usually 3/5 the size of the new hydra.
6- Wasps
Asexual reproduction of wasps is complicated. When certain species become infected with bacteria Wolbachia , The chromosomes in the wasp eggs change. As a result, eggs are not divided, and instead of creating single offspring, wasps mothers create female clones of themselves.
While it sounds like a neat survival trick, wasps are just buying time. Finally, bacteria create only infected female clones. The Wolbachia Is a bacterium that lives within the ovaries and testes of many arthropod species, wreaking havoc on sexual lives and gender proportions.
In wasps, the Wolbachia Has eliminated the males completely, making the egg develop like a female.
In wasps, the infection seems to be innate; In the laboratory, the bacteria could not be transferred between the wasps. That led researchers to speculate that the wasp and its parasite could be species in co-speciation, an event that occurs when a symbiotic relationship between two organisms leads to a change and creates a new species in the process.
Whenever a wasp line diverged into two species, a new strain of Wolbachia Is developed in each species isolated from the wasp.
7- Sea stars
Starfish (scientific name Asteroid ) Are the main group of echinoderms. There are about 2,000 species of starfish that live in the world's oceans in tropical coral reef habitats, seaweed forests in the deep and cold oceans. All starfish are marine animals.
Starfish can reproduce sexually and asexually. In sexual reproduction, fertilization occurs in water with males and females releasing sperm and eggs into the environment. Fertilized embryos, which are free-swimming animals, become part of zooplankton in most species.
Finally, the larvae undergo metamorphosis, settle in the background and grow into adults. Some species cover their eggs, either simply sitting on them, or using specialized baskets.
Asexual reproduction is by fragmentation, a part of an arm and part of the central disc is separated from the"father"and becomes an independent individual starfish.
In the past, many starfish have been exterminated by cutting them into pieces, but the starfish have been able to regenerate and become more starfish.
8- Blind shingles
The Ramphotyphlops braminus Is a very common species, but seldom seen, that spends much of its time digging in the soil and litter. They can be found when digging in soil, when turning logs or rocks or after a heavy downpour when they are forced to leave to the surface of the ground. This is one of the smallest snakes in the world, which rarely exceeds 20 cm in length.
The body is dark brown to black everywhere. The head is barely perceptible from the body, and the tiny eyes appear as blackheads. Virtually blind this serpent can, however, distinguish between light and darkness. The tail is short and forceful and has a short, sharp spine.
Blind shrimp Brahminy feeds on small invertebrates, mainly larvae of ants and pupae. It is one of only two species of Ophidians reproduced by parthenogenesis and by fragmentation, ie, all specimens are females and their reproduction is asexual.
According to the Virtual Encyclopedia of Spanish vertebrates, and according to Das and Ota (1998), Pellegrino et al. (2003) or Arias (2012):
"The evolution towards parthenogenesis in this and other reptiles seems to have its origin in the crossing between individuals of well differentiated species, in such a way that part of the Hybrid females thus generated would lose the ability to reduce the number of oocyte chromosomes during meiosis. When diploid eggs are fertilized by haploid spermatozoids they finally produce triploid females capable of reproducing without the need for males, but generating only their own clones."
9- Sea anemones
Depending on the species, sea anemones reproduce sexually or asexually. During sexual reproduction, the eggs and sperm are released through the mouth.
Asexual reproduction occurs through longitudinal fission, binary fission or laceration of the pedal. Sea anemones do not have a larval form, but develop an egg that once fertilized is converted first into a plantlet and then into a sedentary polyp.
In sexually reproducing marine anemones, some species have separate sexes, while others are protandemic hermaphrodites, which are males that later become females.
Marine anemones reproducing asexually through longitudinal or binary fission are divided in half along their length to form two fully formed individuals.
When sea anemones reproduce through laceration of the pedal, pieces of their pedal disc, they break, settle down and grow into new anemones. Because sea anemones are mostly sedentary, parents and offspring grow close to each other, forming colonies that sometimes live and grow for decades.
10- Sea urchins
Sea urchins are echinoderms, a strictly marine group of invertebrates. Reproduction can be asexual and sexual reproduction. The form of asexual reproduction in sea urchins is a process known as fragmentation. This is when the body of an animal is divided into two or more parts, and both become individual animals.
11- Sea cucumbers
The Stichopus chloronotus Is a species able to reproduce sexually and asexually. In addition, seven other Aspidochirotida Are capable of this unusual reproductive strategy.
Asexual reproduction in these species is carried out through the transverse fission process. In most sea cucumber species capable of reproducing asexually, a method is used in which the anterior and posterior extremities of the organism rotate in opposite directions.
After a while, the two ends move slowly in different directions, eventually causing the body wall to break and divide the organism into two separate individuals.
However the Stichopus chloronotus Uses a different transverse fission method to divide. More specifically, the body begins by creating a constriction in the center of its body. As the posterior region of your body remains stable, the anterior end begins to move forward.
This results in a more intense constriction in the center of the body. As the front end moves further away from the back, the constriction at the center, or fission site, begins to become a fluid substance. Subsequently, the two halves are easily separated.
Based on a study, this whole process only takes a few minutes. After fission, it takes about a day for the tissue at the site of fission to heal.
The body wall of the Stichopus chloronotus Is often referred to as"captive connective tissue"and is very thin and fluid. It is believed that this tissue is the reason why it is possible for the sea cucumber to undergo transverse fission more easily than other species capable of the phenomenon.
In addition, it is thought that this tissue also helps the Stichopus chloronotus After fission has occurred. Transverse fission usually occurs during June in the Indo-Pacific region and is also thought to occur mainly overnight.
12- Sea lily
Crinoidea, phylum Echinodermata . These animals reproduce sexually and asexually as all echinoderms.
Asexual reproduction in sea lilies generally involves the division of the body into two or more parts (fragmentation) and regeneration of the missing body parts. Successful fragmentation and regeneration require a body wall that can be torn and an ability to seal resulting wounds.
Successful regeneration requires that certain parts of the body be present in the lost parts.
13- Sea sponges
According to the University of Wisconsin La Crosse, sponges can reproduce asexually through external budding (or internal budding) and regeneration of broken pieces that become sponges of whole body by themselves.
Sponges can also be sexually reproduced. The external sprouting method of asexual reproduction involves an immature young sponge that forms at the outer base of the sponge. These outbreaks can completely separate and become a separate sponge, or they can remain close to your sponge to form a colony of sponges.
According to the University of California at Berkeley, the asexual gemstone method is more common for sponges. The gemmules are essentially a package of inner buds in the form of cells that are inside a protective coating.
They can be released when the father's sponge dies, usually due to poor conditions, including seasonal cold. The gemmules can then exist within the protective package until conditions improve, at which point they settle and mature into sponges.
Finally, because sponges have regenerative powers, the particles that separate from an established adult sponge may eventually become a living sponge. The sponge from which the particle was broken will regenerate its tissue to replace the lost piece that is now becoming a new sponge.
14- Amebas
According to Jennifer Welsh of Live Science, amoebas reproduce asexually through a process called binary fission.
This refers to the act in which the nucleus of a cell is stimulated to divide into an equal and exact replica of itself within the same cell walls, after which the two nuclei separate into their own individual cells, resulting in two Sovereign but genetically identical amoebae.
15- The locha, sand dollar or sea biscuit
Leodia sexiesperforata . Sand dollars reproduce sexually and asexually. Female sand dollars distribute eggs in ocean water while males float by.
The male sand dollar expels the sperm over the eggs to fertilize them. The fertilized eggs float to the sea, become larvae and finally settle on the seabed where they continue their life cycle.
Sand dollars are marine invertebrates belonging to the echinoderm family. This family also includes fragile stars, sea urchins and sea cucumbers.
Spiny echinoderms, such as starfish and sea urchins, can reproduce asexually by rejuvenating or reproducing damaged limbs and spines. Since sand dollars are rounded animals with no thorny arms, they can rejuvenate the damage done to their body structure asexually.
The male and female sand dollars are identical without distinguishable marks to identify their sex. Researchers at the National Library of Medicine report that sand dollar larvae Dendraster excentricus Cloned when predators are near.
This means that sand dollar larvae have the ability to reproduce asexually when threatened in an attempt to protect and propagate their species. Cloned larvae are much smaller in size than their original counterparts, making them difficult to detect by predators.
For larvae to clone, their environmental conditions should be favorable for growth and reproduction.
16- Planarias
Planarians are able to reproduce sexually or asexually, depending on species and reproductive circumstances. The planarias are hermaphrodites and the mating is that the partners exchange sperm with each other before leaving to lay eggs.
Despite the similarity of Planarian sexual reproduction with that of other animals, planarians are able to reproduce asexually by binary fission. This mechanism takes advantage of the extreme ease of planarias to regenerate the lost sections of their bodies.
Once the planar is divided in half - a division that can occur along any axis of your body: latitudinal, longitudinal or coronal - each section of the body activates special cells called neoblasts.
Neoblasts are adult stem cells that can be divided into new cell lineages that then specialize in all body tissues. The neoblastos in the place of the rupture begin to generate new tissue to replace the structures that each half has lost, which gives rise to two new flatworms.
This process of reproduction through division of the whole body can occur as a result of a traumatic injury, or can be initiated by the planar itself as a normal process called transverse fission. When the planaria begins the process, its body is divided latitudinalmente between the sections of head and tail.
17- Paramecio
The paramecium reproduces sexually and asexually. Asexual reproduction takes place by the binary fission method First, the micronucleus is divided into 2 nuclei by mitosis. The macronucleus is divided into 2 by mitosis.
The cytopharyngeal is also divided into 2 parts. The cytoplasm is also divided into 2 parts. Then the transverse constriction is made from two sides. New contractile vacuoles are formed. The constriction meets in the middle and two daughters paramecias have been reproduced.
18- Water fleas
Daphnia pulex . Water fleas reproduce asexually and sexually and have a cyclic parthenogenetic life cycle, exhibiting heterogeneous reproduction. In asexual reproduction, females produce diploid eggs that become exact clones.
Only females occur during cycles of asexual reproduction. However, during adverse conditions (low food availability, extreme temperatures, high population density), this species reproduces sexually.
During sexual reproduction, males grapple with females using their second specialized antennas.
19- Scorpions
Scorpions are arthropods, arachnids. Within the scorpions there are 13 families that comprise more than 1,700 different species. Some species reproduce asexually, but most reproductive cycles of the scorpion have a single basic pattern.
Parthenogenesis is a rare phenomenon in scorpions, and it can be observed remarkably in species Tityus serrulatus Lutz & Mello from Brazil, Tityus columbianus (Thorell) of Colombia and Tityus metuendus Pocock Of Peru and Brazil. The parthenogenesis of the Thelytokous (with all the female offspring) is observed more frequently.
twenty- Salamanders
It has been determined that some salamanders of the genus Ambystoma Are reproduced asexually by a process called gynogenesis. Ginogenesis occurs when the spermatozoon of a diploid male stimulates the development of a female triploid ovule, but never joins the new zygote.
In the gynogenesis of this type of salamanders only composed by females, the ovule requires the activation by a spermatozoon to initiate its division and to develop, but previously it must duplicate its genetic material through an endomitosis process to avoid the formation of invidious haploid zygotes .
References
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