How often do starfish multiply through fragmentation

20 fascinating asexual animals

Compilation of asexual animals whose reproduction requires only one parent and which results in the offspring being genetically identical to their parents because there is no fusion of gametes. That means they are clones.

Here is a list of 20 animals that reproduce asexually:

Top 20 Most Awesome Asexual Animals

1- Marbled crab

These types of crustaceans, which look like fangs, are an asexual form of crayfish that live in Florida and South Georgia.

The spotted crab is an invasive species that has established populations in three countries while transforming native wildlife at the same time. Many jurisdictions regulate the import and release of various types of cancer. In 2011, Missouri added the marbled crab to its list of prohibited species.

Marbled crabs perform asexual reproduction through apomixis, a process normally reserved for plants in which an organism can produce an embryo without fertilization.

2- tail lizard whip

Cnemidophorus from the family Teiidae. These types of lizards are only female. They usually go through some kind of pseudo-collapse where two women pretend they are a man.

Although it is not strictly necessary to reproduce, this simulated sex has been shown to increase fertility in lizards in particular by acting on copulation and the production of more eggs than those who do not.

The lizard that simulates the female role will produce larger eggs than the one that plays the male role.

Although there is no external fertilization, the lizards' offspring are not really perfect clones of one another. Recent research has shown that the New Mexico Whiptail lizard produces twice as many chromosomes as other species of lizards.

"Parthenogenesis" is the technical name for the reproduction of the New Mexico Whiptail lizards. It comes from the Greek "Parthenos" which means "virgin" and "Genesis" which means "birth". Parthenogenesis is the virgin development of the ovules without prior fertilization.

3- Komodo dragons

Varanus komodoendis. This species of lizard, the largest in the world, can reach just over 3 meters and it has recently been shown that females can reproduce without being fertilized by a male.

This phenomenon was discovered in two captive dragons in two London zoos who fertilized each other as father and mother at the same time.

From the eggs of this type of self-pollination, only the eggs with male genes emerge. This discovery is significant as the Komodo dragons are critically endangered and only about 4,000 remain on the planet.

It can then be determined that parthenogenesis allows the Komodo dragons to reproduce their species by establishing an active population in which they can reproduce sexually and preserve the spice.

4- sharks in captivity

Sharks living in captivity reproduce, if only rarely, asexually. Hammer females, captured as offspring in Florida, USA, and kept away from males, were the first to reproduce asexually.

The asexual reproduction that occurs in hammerhead sharks is also known as parthenogenesis. It refers to the female's ability to create and maintain shark offspring without a male shark, without ever having mated.

This has only been observed in captive sharks, but it can occur in the wild where there is a shortage of male sharks. Although this phenomenon is extremely strange, asexual reproduction has been observed in some limited sharks.

Extensive tests (including paternity tests) were performed after the puppy was discovered. It was confirmed that some females never had contact with another shark and the possibility that sperm from previous encounters were withheld was ruled out.

5- hydra

The hydra is a Cnidario. An organism made up entirely of fresh water and there are many different types of hydra. It's relatively small, averaging just half an inch in length.

The hydra has a tubular body, a "head" at the distal end and a "foot" at the proximal end. You 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. Hydra only has ectoderm and endoderm (not mesoderm). Hydras generally reproduce asexually. Asexual reproduction of Hydra generally occurs in environments with an excess of food.

The first step in the reproduction of the asexual hydra is the onset of the yolk, during which the first signs of an outbreak appear. After the tentacles begin to grow and the mouth of the new hydra begins to develop. After the separation of the new hydra begins, separation of the seed from the original hydra occurs.

This is followed by the replacement of the New Hydra, which is the final step in the reproductive cycle of the Asexual Hydra. In this step, the new hydra is released from the mother, creating an entirely new hydra. This new hydra is generally 3/5 the size of the new hydra.

6- wasps

Asexual reproduction of wasps is complicated. When certain species become infected with the bacteria Wolbachiathe chromosomes in the wasp eggs change. As a result, the eggs do not divide, and instead of creating individual offspring, wasp mothers create female clones of themselves.

While it sounds like an orderly survival trick, wasps are only buying time. Ultimately, the bacteria only produce infected female clones. The Wolbachia It is a bacterium that lives in the ovaries and testes of many types of arthropods, causing havoc in sex life and gender ratios.

In the wasps that Wolbachia It completely eliminated the males, which resulted in the egg developing like a female.

In wasps the infection appears to be innate; In the laboratory, bacteria could not be transmitted between wasps. This led the researchers to speculate that the wasp and its parasite might be species in co-pecking, an event that occurs when a symbiotic relationship between two organisms results in a change, creating a new species in the process.

Whenever a line of wasp diverged into two species, a new species of Wolbachia it develops in every isolated species of wasp.

7- starfish

The starfish (scientific name) Asteroidea) are the main group of echinoderms. There are about 2,000 species of starfish that live in tropical coral reef habitats in the world's oceans, kelp forests in deep and cold oceans. All starfish are marine animals.

Starfish can reproduce sexually and asexually. In sexual reproduction, fertilization occurs in the water, with males and females releasing sperm and eggs into the environment. Fertilized embryos, which are free-swimming animals, become part of the zooplankton in most species.

The larvae eventually go through a metamorphosis, settle on the ground and grow up. Some species cover their eggs by simply sitting on them or using special baskets.

Asexual reproduction occurs through fragmentation, 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 were eradicated by cutting them into pieces, but starfish were able to regenerate and become more starfish.

8- Blind culebrilla

The Ramphotyphlops braminus It's a very common, but rarely seen, species that spends significant time digging into the ground and foliage. They can be found by digging in soil, turning blocks or rocks, or after a heavy downpour when it is forced to come to the surface of the ground. This is one of the smallest snakes in the world, rarely more than 8 inches long.

The body is dark brown to black everywhere. The head is barely noticeable to the body and the small eyes appear as black dots. Practically blind, however, this snake can distinguish between light and dark. The tail is short and blunt and has a short and sharp back.

The blind brahminy shingles feed on small invertebrates, mainly larvae of ants and pupae. It is one of the only two types of ophidians that reproduce through parthenogenesis and fragmentation, meaning that all specimens are females and their reproduction is asexual.

According to the Virtual Encyclopedia of Spanish Vertebrates and Das and Ota (1998), Pellegrino et al. (2003) or Arias (2012):

“Evolution towards parthenogenesis in this and other reptiles seems to have arisen from a cross between individuals of different species, so that part of the hybrid females would lose diploids so creating the possibility of reducing the number of chromosomes in the egg cell during meiosis Wenn When the diploid ovules are fertilized by haploid sperm, they eventually form triploid females that can reproduce without needing males, but only to produce their own clones. "

9 - sea anemones

Depending on the species, sea anemones reproduce sexually or asexually. During sexual reproduction, the ovules and sperm are released through the mouth.

Asexual reproduction occurs through longitudinal cleavage, binary cleavage, or the tearing of the pedal. Sea anemones do not have a larval form, but rather develop an egg that, once fertilized, first becomes a planula and then a sedentary polyp.

In sea anemones that reproduce sexually, some species are of different sexes while others are protruding hermaphrodites, which are males that later become females.

Sea anemones, which reproduce asexually by longitudinal or binary cleavage, are split in half along their length to form two fully formed individuals.

When sea anemones are reproduced by pedal ripping, pieces of your pedal disk are broken, established, and grown into new anemones. Since sea anemones are mostly sedentary, parents and offspring grow close together and form colonies that sometimes live and grow for decades.

10 - sea urchin

Sea urchins are echinoderms, a strictly marine group of invertebrates. Its reproduction can be asexual and sexual reproduction. The form of asexual reproduction in sea urchins is a process known as fragmentation. This is when an animal's body is divided into two or more parts and both become separate animals.

11 - sea cucumber

The Stichopus chloronotus It is a species that can reproduce sexually and asexually. In addition, seven other types of Aspidochirotida They are capable of this unusual reproductive strategy.

The asexual reproduction of these species occurs through the transversal cleavage process. Most species of sea cucumber that can reproduce asexually use a method in which the front and rear ends of the organism rotate in opposite directions.

After a while, the two ends slowly move in different directions, which eventually leads to the breaking of the body wall and dividing the organism into two separate individuals.

But the Stichopus chloronotus uses another method of cross-splitting to divide. More precisely, the organism begins by creating a constriction in the center of its body. While the back of your body remains stable, the front end begins to move forward.

This leads to a greater narrowing in the middle of the body. As the anterior end moves further away from the posterior part, the narrowing in the center or the cleavage site begins to become a liquid substance. Then the two halves separate slightly from each other.

Based on a study, this whole process only takes a few minutes. After the split, it takes about a day for the tissue at the split site to heal.

The wall of the body of Stichopus chloronotus Often referred to as "trapped connective tissue", it is very thin and fluid. It is believed that this tissue is what makes it possible for the sea cucumber to cross-split more easily than other species capable of this phenomenon.

In addition to this, it is believed that this substance also helps the quick recovery it has Stichopus chloronotus after the split has taken place. The transverse splitting usually occurs in June in the Indo-Pacific region and is believed to occur primarily overnight.

12 - water lily

Crinoidea, phylum Echinodermata. These animals reproduce sexually and asexually like all echinoderms.

Asexual reproduction in water lilies usually involves dividing the body into two or more parts (fragmentation) and regenerating the missing parts of the body. Successful fragmentation and regeneration require a wall of the body that can be ruptured and an ability to seal the resulting wounds.

Successful regeneration requires certain parts of the body to be present in the lost pieces.

13 - sea sponges

According to the University of Wisconsin La Crosse, sponges can reproduce asexually through external sprouting (or internal sprouting) and the regeneration of broken pieces that become sponges themselves.

Sponges can also reproduce sexually. The external germination mode of asexual reproduction involves an immature young sponge that forms on the external base of the sponge. These buds can separate completely and become a separate sponge, or they can stay near your sponge to form a colony of sponges.

According to the University of California at Berkeley, the asexual method of reproduction is more common for sponges. Gemulas are essentially a bundle of inner buds in the form of cells that are contained in 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 inside the protective packaging until conditions improve, in which they settle and mature into sponges.

Eventually, because the sponges have regenerative powers, the particles that separate from an established adult sponge can eventually become a living sponge. The sponge that breaks the particle regenerates its tissue to replace the lost piece, which now becomes a new sponge.

14 - Amebas

According to Live Science's Jennifer Welsh, amoebas reproduce asexually through a process called binary fission.

This refers to the process by which the nucleus is stimulated to divide into an equal and exact copy of itself within the same cell walls, after which the two nuclei divide into their own individual cells, resulting in two sovereign but genetically identical ones Amoeba.

15 - The loach, sand dollar or sea biscuit

Leodia sexiesperforata. Sandy Dollars reproduce sexually and asexually. The female sand dollars disperse the eggs in the ocean water while the males float by.

The male sand dollar drives the sperm onto the eggs to fertilize them. The fertilized eggs float towards the sea, they become larvae and finally they settle at the bottom of the sea, where they continue their life cycle.

Sandy dollars are marine invertebrates that belong to the echinoderm family. This family also includes fragile stars, sea urchins, and sea cucumbers.

Thorny echinoderms like starfish and sea urchins can reproduce asexually by rejuvenating or restoring damaged limbs and spines. Because sand dollars are rounded animals with no thorny arms, they can rejuvenate the damage that is asexually inflicted on their body structure.

The male and female sand dollars are identical with no recognizable markings to identify their gender. Researchers at the National Library of Medicine in the United States report that sand dollar larvae Dendraster excentricus clone when predators are near.

This means that sand dollar larvae have the ability to asexually reproduce when threatened to protect and reproduce their species. The cloned larvae are much smaller than their original counterparts, making them difficult to spot by predators.

In order for the larvae to clone, their environmental conditions must be favorable for growth and reproduction.

16 - planarians

The planarians can reproduce sexually or asexually, depending on the mode and circumstances of reproduction. The planarians are hermaphroditic and mating consists in the partners exchanging seeds with one another before laying eggs.

Despite the similarity of planar sexual reproduction with that of other animals, planarians are able to reproduce asexually through binary fission. This mechanism uses the extreme lightness of the planarians to regenerate the lost body sections.

Once the planarians are divided into two parts - a division that can take place along any axis of your body: latitudinal, longitudinal, or coronal - each part of the body activates special cells called neoblasts.

The neoblasts are adult stem cells that can be divided into new cell lines that then specialize in all body tissues. The neoblasts at the site of the break begin to create new tissue to replace the structures that each half lost, resulting in two new flatworms.

This process of reproduction through the division of the whole body can occur as a result of traumatic injury, or it can be initiated by the planaria itself as a normal process called transverse splitting. When the planarians begin the process, their body is divided widthwise between the head and tail.

17 - Parametrics

The Paramecium reproduces sexually and asexually. Asexual reproduction takes place according to the method of binary splitting: First, the micronucleus is divided into 2 nuclei by mitosis. The macronucleus is divided into 2 by mitosis.

The citpharyngeal is also divided into 2 parts. The cytoplasm is also divided into 2 parts. Then the transverse narrowing is made from two sides. New contractile vacuoles are formed. The narrowing meets in the middle and two Paramecia daughters have been reproduced.

18 - water fleas

Daphnia pulex. Water fleas reproduce asexually and sexually and have a cyclical parthenogenetic life cycle with heterogeneous reproduction. When reproduced asexually, females produce diploid eggs that become accurate clones.

Only females occur during asexual reproductive cycles. However, under adverse conditions (low food availability, extreme temperatures, high population density) these species reproduce sexually.

During sexual reproduction, the males cling to the females with their second specialized antennae.

19 - Scorpions

Scorpions are arthropods, arachnids. There are 13 families within the Scorpios, comprising more than 1,700 different species. Some species reproduce asexually, but most of the scorpion's reproductive cycles have a single basic pattern.

Parthenogenesis is a rare phenomenon in scorpions and can be observed especially in species Tityus serrulatus Lutz & Mello from Brasil, Tityus columbianus (Thorell) of Colombia and Tityus metuendus Pocock from Peru and Brazil. The parthenogenesis of Thelytokous (with all female offspring) is observed more often.

20 - salamander

It was found that some salamanders of the genus Ambystoma they reproduce asexually through a process called gynogenesis. The ginogénesis occur when sperm from a diploid male stimulate the development of a triploid female egg but never entered the new zygote.

In the ginogénesis of this type of salamander composed only by women, the egg requires activation by a sperm cell to divide and begin developing, but above its genetic material must be duplicated through a process of endomitosis to prevent the formation of haploid zygotes being unviable.


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