Gemmule, Gemmulation: Definition, Meaning, Introduction, Parts, Structure, Characteristics
Gemmules and gemmulations are one of the unique forms of asexual reproduction seen primarily in freshwater sponges like Spongilla. The structures are small, tough, and resistant internal buds which help the organisms survive in harsh environmental conditions, like cold and drought. These bodies are formed by the aggregation of the amoeboid cells (also called archaeocytes), are surrounded by a protective covering of spicules.
This Story also Contains
- What are Gemmules?
- Formation of Gemmules (Gemmulation)
- Anatomy and Structure of Gemmules
- Biological Significance of Gemmules
- Ecological and Evolutionary Factors
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Gemmulation is the process of the formation of gemmules inside the parent sponge’s body. On the occasion of the death of a parent, sponge or environmental conditions become favourable again, gemmules germinate to form new sponges. This adaptation ensures species continuity even when external factors are unfavourable. It is an important topic in the field of biology.
What are Gemmules?
Gemmules are bodies for reproduction that some sponges develop, particularly in unfavourable conditions of the environment. The bodies are composed of a mass of cells that is enveloped in a hard covering, enabling them to withstand unfavourable conditions. Should favourable conditions occur, the gemmules can readily grow into new sponges and, therefore, aid in the survival of their species.
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Formation of Gemmules (Gemmulation)
Gemmules are formed by internal budding in the Phylum Porifera when environmental conditions become harsh. Specialised cells called archaeocytes gather and are enclosed in a tough protective layer. This dormant structure helps the sponge survive until conditions improve.
Step-By-Step Explanation
Induction: Environmental stress signals the commencement of gemmule development in the sponge.
Nutrient Accumulation: Specialised cells called archaeocytes gather undigested food particles and other required materials.
Protective Layer Formation: A tough protective layer forms around the mass of archaeocytes.
Release: The mature gemmules are released into the environment. There, they go into dormancy and just wait for things to get better.
Environmental Triggers of Gemmulation
Temperature change.
Desiccation.
Low food availability.
Water pollutants.
Anatomy and Structure of Gemmules
A gemmule contains a cluster of archaeocytes surrounded by a protective covering made of spicules and spongin. It also has a micropyle through which cells can emerge. This structure ensures durability and regeneration capacity.
Protective Layers
Outer spicule layer: The layers function as physical barriers and provide mechanical protection against any damage.
Inner resistant layer: The inner layer functions to protect the gemmule from biological and chemical threats.
Internal Cells
Archaeocytes: These undifferentiated cells are able to develop into various other cell types. These are the totipotent cells needed for sponge development.
Biological Significance of Gemmules
Gemmules help the sponges to survive during extreme conditions like drought or cold. When the conditions become favourable, they form new individuals. This proves as a reliable method of asexual reproduction.
Survival Strategy in Harsh Conditions
Gemmules help the sponges to survive during unfavourable conditions.
Protects internal cells from desiccation and extreme temperatures.
Allows for long-term survival in the dormant state.
Function in Dispersal and Regeneration
Gemmules spread over a wide area; therefore, they allow the colonisation of new habitats.
When favourable conditions return, gemmules germinate and grow into new sponges. Examples in various species of sponges: Freshwater sponges form gemmules as a means of surviving winter.
In marine sponges, such structures are resistant to low temperatures and salinity fluctuations.
Ecological and Evolutionary Factors
Gemmules help the sponges to pass unfavourable conditions such as drought, extreme temperature, and pollution by entering a dormant state. This adaptation ensures their survival and dispersal in the changing environmental conditions.
Adaptation and Mechanisms of Survival
Gemmules help the sponges to survive the extreme conditions of cold or drought.
They function as a mechanism for asexual reproduction, which ensures the continuity of a species during periods when conditions are not favourable for sexual reproduction.
Gemmules are a means of survival during these unfavourable conditions, which leads to the production of a tough-coated cluster of embryonic cells.
It is a method of propagation when the environmental conditions become unfavourable.
Also Read:
| Micropropagation | Sporulation |
| Syngamy | Morphallaxis |
| Difference Between Partenocarpy and Parthenogenesis | Difference Between Apomixis and Parthenogenesis |
Frequently Asked Questions (FAQs)
Gemmules can enable the sponges to survive adverse environmental conditions and ensure their regeneration and dispersal when conditions improve.
Such characteristics of resilience and regeneration of gemmules can also be utilised in many scientific studies, more so in fields of mechanisms of survival and cellular regeneration.
Gemmules are reproductive structures produced by sponges to survive adverse conditions and then regenerate. The process is known as gemmulation.
One is budding, in which a new organism grows from an outgrowth of the parent, while the other, gemmulation, is the production of gemmules, themselves capable of surviving such adverse conditions and later developing as new sponges.