Hermaphroditism is a very striking reproductive strategy because it is present in very few vertebrates. Being a rare event, it sows many doubts around it. To help solve these doubts on our site we have prepared this article, so that it is understood why some animal species have developed this behavior. We will see it with different examples of hermaphrodite animals.
The first thing we must bear in mind when talking about the different reproductive strategies is that cross fertilization is what all organisms seek. Self-fertilization is a resource that hermaphrodites have, but not its purpose.
First, understand the vocabulary
To better explain the reproduction of hermaphrodite animals, we will clarify some terms:
- Macho: has male gametes.
- Female: Has female gametes.
- Mermaphrodite: has male gametes and female gametes.
- Gametes: they are the reproductive cells that carry the genetic information, sperm and egg.
- Cross fertilization: two individuals (one male and one female) exchange gametes with genetic information.
- Self-fertilization: the same individual fertilizes its female gametes with its male gametes.
Difference between outcrossing and selfing
In cross fertilization there is greater genetic variability because it is mixes the genetic information of two animals. Self-fertilization causes two gametes with the same genetic information to mix, resulting in an individual identical, in this cross there is no possibility of genetic improvements and their descendants are usually weaker. This reproductive strategy is generally used by groups of animals with slow locomotion, for which it is more difficult to coincide with other specimens of the same species. Let's put ourselves in a situation with an example of a hermaphrodite animal:
An earthworm, which is buried moving blindly through the humus layers. When the moment of reproduction arrives, it does not find another specimen of its species anywhere. And when it finally finds it, it goes and it is of the same sex, so they could not reproduce. To avoid this problem, they have developed the ability to carry both sexes inside them, so when they mate, both worms leave fertilized. In the event that it did not find another individual in its entire life, it could self-fertilize to ensure the survival of the species
I hope that with this example it will be understood that hermaphroditism is a tool to double the chances of cross-fertilization and not a self-fertilization tool.
Types of hermaphrodite animals and their reproduction
Below, we show a list of hermaphrodite animals, a few examples to better understand this type of reproduction:
Earthworms
They have both sexes at the same time and, therefore, throughout their lives they have developed both reproductive systems. When they mate, both worms are fertilized and then lay a bag of eggs.
Leeches
Like earthworms sor permanent hermaphrodites.
Shrimp
They are usually males at early ages and females at mature ages.
Oysters, scallops, scallops and scallops
They also have sexual alternation, and currently the Aquaculture Institute of the University of Santiago de Compostela is studying the factors that induce the sex change. In the image you can see a scallop in which you can see the gonad. The gonad is "the sac" that contains the gametes. In this case, half is orange and half is whitish, the chromatic differentiation corresponds to the sexual differentiation and varies at each moment of the life of the organism, this being another example of a hermaphrodite animal.
Sea stars
one of the most popular hermaphrodite animals in the world. They normally develop the male gender in juvenile phases and change to female with maturity They can also have asexual reproduction, which occurs when an arm breaks carrying a part of the center of the star. In this case the star that lost the arm will regenerate it and the arm will regenerate the rest of the body. Thus giving rise to two identical individuals.
Had
Its condition as internal parasite makes it very difficult for it to reproduce with another organism. For this reason, they usually resort to self-fertilization. But if he gets the chance he proceeds to cross-fertilize.
Fishes
It is estimated that 2% of fish species are hermaphrodites, but like most they live in the deepest layers of the ocean its study becomes very complicated. In the coastal reefs of Panama, we have a peculiar case of hermaphroditism. The Serranus Tortugarum, a fish that has both sexes developed at the same time and alternates with its partner up to 20 times a day.
There is another case of hermaphroditism carried out by some fish and that is the change of sex for social reasons. This occurs in fish that live in colonies, a larger dominant male and a group of females. When the male dies, the larger female takes on the role of dominant male and a sex change is induced in her. These little fish are some examples of hermaphrodite animals:
- Cleaner Lord (Labroides dimidiatus)
- clownfish (Amphiprion ocellaris)
- old blue lady (Thalassoma bifasciatum)
This behavior is also shown by our adorable guppy fish, so common in aquariums.
Frogs
There are some species of frogs such as the African tree frog (Xenopus laevis) that are male in their juvenile stages and turn female with Adulthood.
Commercially used atrazine-based herbicides are rapidly changing sex in frogs. An experiment at the University of Berkeley in California has found that if males are exposed to low concentrations of this substance, 75% of them are chemically sterilized and 10% become females directly.
Other examples of hermaphrodite animals
In addition to the previous species, the ones shown below are also part of the list of hermaphrodite animals:
- Slugs
- Snails
- Sea dancers
- Lapas
- Flatworms
- Blisterbread
- Flukes
- Sea sponges
- Corals
- Anemones
- Freshwater Hydra
- Amoebas
- Salmon
