It is a genus of sponges found in the freshwater, slow streams and lakes, belonging to the family Spongillidae. Spongilla genus sponges stick themselves to the logs and rocks and filter the water for numerous smaller aquatic organisms including bacteria, protozoans, and other free-floating pond organisms.
Spongilla genus sponges are freshwater sponges and are different from marine sponges as they get exposed to more harsh, diverse, and changing environmental conditions. For this reason, they have gemmules developed in them for dormancy.
Knowing about the gemmules, these are internal buds that are found in sponges and play an important role in asexual reproduction. An adult sponge can develop from these asexually reproduced masses of cells.
The process of the asexual reproduction performed by sponges is budding through external or internal buds (gemmules). Since the gemmules are resistant to drying out or desiccation, lack of oxygen, freezing, and can lie around for a longer time.
When conditions are favorable, the gemmules germinate and form a new sponge. Sponges also have spicules that are present on the dermal layer providing skeletal framework and protection.
Spongilla for the NEET exam is important; let’s discuss it more in detail.
Spongilla is classified under phylum Porifera and these belong to the class Deospongiae. The common Spongilla species is Spongilla lacustris. Below is a tabular representation of the spongilla classification.
Classification of Spongilla
Examples of Spongilla
Following are some of the spongilla examples which belong to different species:
Structure of Spongilla
Let’s learn some points about the Spongilla structure from the following section:
Spongilla is normally yellowish brown colored, consisting of multiple small individuals having a common flat base.
Spongilla is a common freshwater sponge which is usually colonial and attached to sticks or wood pieces found in lakes and ponds.
Every Spongilla individual is perforated with numerous Ostia and one osculum (which can be one for one individual or one for many individuals).
Spongilla has a rhagon type of canal system and its skeleton comprises spongin fibers having silicious monaxon spicules.
Being delicate in structure, sponges grow as encrusting or branching masses and because of the algae that thrive on them, they appear greenish many times.
Spongilla may attain a volume of over 2.5 K cubic centimeters.
(image will be uploaded soon)
Characteristics of Spongilla
In this section, we will discuss certain spongilla characteristics that help us to identify and understand their behaviour.
Spongilla may be unbranched/branched and consist of numerous Ostia found all over the surface.
Their color ranges from light yellow to green and it depends upon the number of zoochlorellae living on them. Zoochlorella is a green algae having a symbiotic association with it.
As discussed earlier, spongilla is found in slow streams, lakes, and freshwater. These get attached to logs, sticks, and submerged plants.
Spicules which support its outer surface may be simple, tetraxial, or siliceous.
It has a leuconoid type of canal system which is complex and a system of interconnected canals leading to irregular symmetry to Spongilla.
Water enters the Ostia and then to incurrent canals that open into flagellated chambers and these chambers are lined by choanocytes. Further, the flagellated chambers open into the excurrent canal and water here flows outside from the osculum.
Extensive division and shrinkage of the spongocoel leads to the formation of excurrent canals.
Diffusion is the process of gaseous exchange and excretion in Spongilla.
These feed on smaller organic particles and on them, many insects depend for feeding.
Spongilla can reproduce asexually or sexually.
Budding is the asexual reproduction through budding or gemmules formation.
These are hermaphrodite and each sponge can produce egg and sperm. One sponge’s sperm reaches another sponge’s Ostia and development takes place inside the cavity to produce free-swimming larvae.