The metamorphosis, in zoology, consists of a transformation experienced by certain animals through which they pass from one form to another, in regular succession, from birth to adulthood. It is part of your biological development and affects not only your physiology, but also your behavior and lifestyle.
In this article on our site we will explain which are animals that undergo metamorphosis in their development, also detailing the phases of metamorphosis or what types of metamorphosis exist. Read on and find out all about this process!
What is metamorphosis?
To better understand what the word "metamorphosis" means, we must know its etymology The term derives from the Greek and is made up of the following words: meta (beyond), morphé (figure or form) and -osis (change of state), therefore, it would be a transformation from one element to another.
So, metamorphosis in animals is a sudden and irreversible change in the physiology, morphology and behavior It is a period in the life of an animal that corresponds to the passage from the larval form to a juvenile or adult form. It affects insects, some fish and some amphibians, but not mammals.
This phase of development is characterized by the birth of an autonomous larva, unable to reproduce sexually until its juvenile or adult stage, known as " imago " or "last stage ". Furthermore, the phenomena of metamorphosis are not only superficial, but also involve extremely profound changes in the animal, such as:
- Organ modification
- Organic tissue modification
- Adapting to a new environment
Types of metamorphosis
Now that you know what metamorphosis is, we'll explain what types exist. However, you should know that, while in insects there is a change at the cellular level, in amphibians it involves a change in the animal's tissues, so it is about different processesFind out below what differences exist between both insect metamorphosis and how it differs from the amphibian metamorphosis:
Metamorphosis in insects
We observed in insects two types of metamorphosis, unlike amphibians, which only undergo one. Next we will explain what they consist of:
- Hemimetabolism: it is also known as simple, simple or incomplete metamorphosis. In this type of metamorphosis, the individual does not experience the "pupa" phase, that is, it does not have a period of inactivity. It feeds constantly, thus increasing its size, until it reaches its adult stage. In the same species, each life form has its own adaptation to the environment. Some examples of animals that suffer hemimetabolism are lobsters or bedbugs.
- Holometabolism: is also known as complete or complicated metamorphosis. In this case we observe several different stages and they all end in the pupal phase (which can last weeks or even years, depending on the species) until the birth of the imago occurs. We observe a radical change in the appearance of the individual. Some examples of animals that suffer from holometabolism are the butterfly, the fly, the mosquito, the bee or the beetle.
- Ametabolism: Also called "Ametabolism", it refers to insects and arthropods that, when they reach their nymphal stage, have some similarities to the adult form. However, there is no metamorphosis, it is a direct expansion. Some examples are lice and mites.
In insects, metamorphosis is controlled by "ecdysone", a steroid hormone that has no juvenile hormones and that plays a key role in maintaining the larval characters in the animal's body. However, there is a growing problem: various insecticides have characteristics similar to these juvenile hormones, so that they end up preventing the metamorphosis of the individual by completely inhibiting them.
Metamorphosis in amphibians
"Metamorphosis in amphibians is the result of the action of thyroid hormone. (Gudernatsch, 1912) Experience shows that a thyroid transplant or thyroid treatment causes metamorphosis."
In the metamorphosis of amphibians we observe a certain similarity with insects, since they also go through a larval phase (tadpole) and a pupal phase (tadpole with limbs) before giving birth to the imago, which would be the adult state. The most common example is the frog.
After the "prometamorphosis" phase, when the animals' toes become visible, an interdigital membrane called the palm connects them to form the paddle-shaped swimming leg. Next, the hormone called "pituitary" passes through the bloodstream to the thyroid. At that time, it stimulates the production of the hormone thyroxine T4 which causes complete metamorphosis
Next we will show you how the phases of metamorphosis occur according to each of the types.
Phases of simple metamorphosis
To better understand the simple or incomplete metamorphosis, we will show you the example of the metamorphosis of the grasshopper It is born from a fertile egg and begins to develop progressively, without going through a chrysalis phase. During the first stages it does not have wings, as they will appear later, as it evolves. In addition, he is not sexually mature until he reaches his adult stage.
Phases of complete metamorphosis in insects
To explain the complete or complicated metamorphosis we have chosen the metamorphosis of the butterfly It begins, as in the previous case, from from a fertile egg, which hatches into a caterpillar. This individual will feed and develop, until the hormones begin to cause the phase change. The caterpillar will begin to wrap itself with a thread that it secretes itself, until it forms a chrysalis that completely covers it.
During this period of apparent inactivity, the caterpillar will begin to reabsorb its juvenile organs and completely transform its body, developing legs and wings. It can last days or weeks. Finally, the pupa will open, giving way to an adult butterfly.
Phases of metamorphosis in amphibians
To explain the stages of metamorphosis in amphibians, we have chosen the metamorphosis of the frog Frog eggs are fertilized in water, while they are surrounded by a gelatinous mass that protects them. They will develop until the larvae are fully formed and then the tadpole will be born, which has a head and a tail. As the tadpole feeds and evolves, it will begin to develop legs and, over time, the figure of the adult frog. Finally, when the loss of the tail occurs, it will be considered an adult and sexually mature frog.
Which animals have metamorphosis?
To finish, we show you a partial list of the zoological groups of animals that undergo metamorphosis in their development:
- Lyssamphibians
- Anuros
- Nicknames
- Urodeles
- Arthropods
- Insects
- Crustaceans
- Echinoderms
- Mollusks (except cephalopods)
- Agnathes
- Salmoniform Fish
- Eelfishes
- Pleuronectiformes Fishes
