Formation and Structure of Gemmules
Gemmules are found in sponges, gemmules are internal buds (embryonic shoot), which plays a significant role in asexual reproduction. In other words, you can define what are gemmules as a cluster of cells capable of growing into an adult sponge.
Now that you are familiar with what are gemmules, let us proceed with what is gemmule formation?
Gemmule Formation in Sponges
Gemmule formation occurs in freshwater by several sponges like Spongilia and some water species such as sea sponges, figuline ficus, and various other types of poriferans. The organisms give out gemmules, which further give birth to new sponges.
Archaeocytes or totipotent cells are filled with food material in the form of lipoprotein or glycoprotein amalgamate to become a mass. Further, an amoebocyte moves around the archaeocyte to provide a surrounding layer. This amoebocyte releases solid chitin, which becomes a layer around archaeocytes.
Freshwater sponges usually die during the autumn season but leave behind a lot of gemmules. These produced internal buds can even withstand and live in winters and summers' adverse and unfavourable conditions. Further, these grow to become new sponges when they find an abundant quantity of water.
Structure of Gemmules
A completely formed gemmule features a standard size, and the structure of the same is similar to a hardball. Alongside reproductive cells, you can also see a food mass embedded in membranes on a grown gemmule.
Plus, gemmules have a tiny opening, which is scientifically termed as a micropyle. When the conditions are favorable for development, cells come out from this opening.
Parts of a Gemmule
Inner layer
Spicule
Micropyle
Archaeocytes
Outer pneumatic layer
Gemmules Classification
In general, there are two categories of gemmules, and the names are:
Single or double-layered coats enclosed by mono or binucleate cells
Triple-layered coats enclosed by binucleate cells
Features of Gemmules
Gemmules can survive without oxygen.
They are the same as a bacterium's endospore.
Gemmules can live in adverse conditions, where sponges may not be able to survive.
Characteristics of Gemmules
Although there isn’t much definition and structure to gemmules, they possess the following characteristics:
i. Gemmules are resistant to drying up, they are resistant to desiccation due to weather, temperature, etc.
ii. They are resistant to freezing, even in winters during the low temperatures.
iii. They are also resistant to anoxia, which means that they can survive even in extreme shortages of oxygen.
iv. They can survive and lie around for long periods of times, which means that they do not degrade, spoil, or rot.
v. Gemmules resemble the endospore of bacteria.
vi. They are composed of amoebocytes.
vii. They are surrounded by a thin layer of spicules for support and to deter the predators.
viii. These gemmules are super degrading resistant and can survive extreme environmental conditions that could even kill fully grown sponges.
ix. The gemmules only resume growing after the environment has become less hostile.
Gemmule Reproduction among Sponges
Do you know that these internal buds show resistance towards freezing and dehydration? Yes, it is true. In fact, gemmules can even live in the absence of oxygen. The exterior gemmule layer is surrounded by endospore, further surrounded by spicule, which also protects. As a result, gemmules can grow into freshwater sponges.
Do it Yourself
a) Write down the parts of a gemmule.
b) Formation of gemmule in sponges is beneficial for:
(i) Sexual reproduction
(ii) Dissemination
(iii) Parthenogenesis
(iv) Asexual reproduction
By now, you must have acquired considerable knowledge related to gemmules. Nevertheless, for more such topics, please prefer to download the Vedantu app today!
FAQs on Gemmules
1. What are the Properties of Spicules of Sponges?
The structures that serve the purpose of a skeleton in sponges are known as spicules. Naturally, spicules can be siliceous or calcareous. Plus, these structures are monaxon, triaxon, and tetraxon, which means they may have one ray, three rays, and four rays, respectively. Furthermore, spicules are released by special scleroblast cells.
2. Which Organisms favours the Process of Budding?
A type of asexual reproduction where a new organism gets produced due to cell division. In yeast cells, the small bulb-like projection is called the bud. As asexual reproduction occurs, the born organism is declared a clone, and it resembles the parent organism, except in cases of mutation.
Hydra utilises regenerative cells in the process of budding for reproduction. Because of repeated cell division at a particular site, a bud develops in hydra. Further, these buds grow into small individuals and parts from the parent body to become separate organisms. Parasites like Toxoplasma gondii also favour internal budding or endodyogeny.
3. Why are many Sponges Green in Colour?
The reason behind the green colour of sponges is that symbiotic bacteria, plantlike protists, and algae are present in them.
4. What is the Triggering Factor for Sponges to Produce Gemmules?
Gemmules are produced because of certain environmental factors like desiccation or low temperatures. The parent body breaks down to give out gemmules that can withstand the harsh conditions.
5. How can I get to understand the Gemmules chapter?
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As this chapter is related to Gemmules and it is an important chapter for the exams, it consists of the important points which are needed for the exams. It can be useful for last-minute revision, students don't have to look at the textbook to search for a particular topic to revise. Everything which is given in the notes can be helpful for a student for the exams.
7. Are the notes of Gemmules in Vedantu enough for the exam point of view?
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8. Is Gemmules a hard chapter in Biology?
Students should study the chapters which are important. The chapter Gemmules is an easy chapter. The trick to understanding is to first clear the concept of it then they will be able to get the formation of sponges. Vedantu has made available the notes for this chapter which are written in a simple way so it will be very easy for the students to get them. They need to remember the parts of a Gemmule and the types of it because they are important in this chapter.
Another important subtopic is the reproduction among sponges which should be mentioned in the notes. Every important thing regarding this chapter is present in the notes of Vedantu, students should make their notes by reading them. This will make it easy to make notes themselves by understanding it.
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