Freshwater Sponge

Freshwater sponges are quite crucial to ecosystem operating; however, information about their biogeography and interspecific differentiation is fragmentary, restricting our ability to assess their role. Although the particulate epithets of two common species indicate that sponges spotted in lentic habitats are Spongilla lacustris, -- also often referred to as spongilla freshwater sponge is a species of sponges from the family Spongillidae. Those found in lotic habitats are Ephydatia fluviatilis, the number of sponge species in the UK is unsettled.

Freshwater sponge, also commonly referred to as Spongilla lacustris, is a species of sponges from the family Spongillidae. They inhabit freshwater rivers and ponds; often develop under rocks or logs. Lacustris is a Latin term implying "linked to or associated with lakes". The freshwater species ranges from North America to Asia and Europe. This freshwater sponge is most commonly found in central Europe. It is the most extensive sponge in Northern Britain, and is one of the most common species of sponges in rivers and canals. Spongilla lacustris possess the potential to reproduce both sexually and asexually. They become inactive during winter. The growth form ranges from encrusting to finger-like, to branched, subjected to the quality of the habitat. 

Refer to the below diagram to see how the freshwater sponge looks like. The diagram is also a clear depiction of the distinction for spongilla freshwater sponge.

[Image will be uploaded soon]                

Freshwater Sponge Scientific Name

Scientific name of spongilla is Spongilla lacustris

Example of Freshwater Sponge

Spongilla is a classic example of freshwater sponge type, from the family Spongillidae. These are mostly found in stagnant streams and water ponds. The skeleton of Spongilla is made of siliceous spicules.

Scientific Description of Freshwater Sponge

Basics of Freshwater Sponges

• Freshwater sponges are non-moving organisms that basically live at the bottom of water bodies.

• Spongilla freshwater sponges are invertebrates (meaning to have no backbone) and do not have organs, but rather consist of specialized cells which enables them to filter water for food.

• The species Ephydatia muelleri most commonly occurs in the National Capital Region (NCR) and is often green-coloured owing to the algae that survive in the structure of the sponge. As a matter of fact, many people misinterpret freshwater sponges for algae, but sponges have a coarse texture and are not slimy or mucky like algae.

• Spongilla species are known to filter organic materials and bacterioplankton from water for food and also eat some products yielded by their symbiotic algae.

• They can reproduce both sexually, or asexually when small pieces are fragmented and formed into new sponges or when the sponge grows gemmules—tiny reproductive provinces that can overwinter and later hatch and form new sponges.

• Gemmules are usually grown in the fall.

• Sponges can be significantly distinguished to the species level only by reviewing the sponge’s gemmule structure using a microscope.

Diagnostic Characteristics of Spongilla Freshwater Sponge

Light tan in summer, at times light grey-green in winter; a hard, disc-shaped blanketed to 30 mm diameter on the undersides of logs and rocks; gemmules and microscleres absent; amphioxus megascleres are common with a slight mid-area bulb and in general, encrusted with short, conical spines other than at their tips; overwinters in a lapsed state in which choanocyte chambers are decreased in number or absent, accompanied by augmentation of excurrent canals. This grey-green species exhibits round gemmules and can reproduce through these tiny gemmules which can hatch to grow new sponges.

Importance of Spongilla Freshwater Sponge

Freshwater sponges occur on strapping submerged objects in clean rivers, ponds and streams. Since they are sensitive to water conditions, their existence suggests superlative water quality and low levels of pollutants.

Sponges are typically the filter feeders. They acquire food from the flow of water by their bodies and through symbiotic algae. They also set out as food for ducks, crayfish, and a number of macro-invertebrates including spongilla flies, caddis flies, midges, and lacewings.

Of the phylum Porifera Spongilla to which all sponges belong, only one family (Spongillidae) appears in freshwaters of the US, the rest occurs in marine environments.

Classification of Spongilla Freshwater Sponge

Spongilla lacustris is a component of the class demosponges of the phylum Porifera. The Porifera phylum comprises all sponges that are featured by the tiny pores on the outer layer that absorb water. The sponge wall cells filter food from the water. Whatever is not gulped down by the sponge is pumped through the body out of a huge opening. The class demosponges are profuse and diverse of the sponge classes. Some of the sponges in this class consist of skeletons composed of silicon-containing spongin fibres, spicules, or both. Demosponges take into account both marine and freshwater sponges.

Reproduction Freshwater Sponge

Freshwater sponges follow the reproductive approach both sexually and asexually, displaying two techniques of asexual reproduction: by gemmules and by budding.

1. Sexual: sexual reproduction occurs during the summers. These spongilla freshwater sponges are hermaphroditic, implying that each sponge processes both sperm and egg. The sperm are dispersed into the water where they will carry into another sponge's ostia. In due course, the sponge gives birth to live, free-swimming larvae after forming in the sponge's inner cavity.

2. Asexual:

1. Gemmules: Gemmules are detailed, highly resistant resting stages developed by freshwater sponges. Gemmules can be formed at any time during the developing season, but the majority of production takes place in the autumn, stimulated by seasonal alterations in temperature and light. They grow by the migration of food-filled archaeocytes, also referred to as amoebocytes, into discrete masses. This archaeocyte core gets encrusted in some different hardened membrane layers, growing a shell. Gemmules are capable of combating repeated freezing and thawing, parching and prolonged darkness. When environmental conditions become better and the water temperature rises from 13 to 23 °C, germination takes place and the young sponge leaves its shell and begins a new animal.

2. Budding: The second asexual technique of reproduction is budding. This takes place in springtime when the sponge develops buds in its outer layer. These will ultimately renounce the initial structure to build a new colony.

Freshwater Sponge Diet and Food Chain

Freshwater sponges are filter eaters that eat small floating organic particles. They are eaten by Sisyridae, a flock of winged insects also referred to as sponge flies. Their larvae play the role of parasites on the sponge and feed customarily on it during its larval stage. Ceraclea are insects that not only feed on the sponges but will use the sponges' spicules to construct hard, protective cases for themselves. As the larva blooms, it not only adds spicules to its protective casing but pieces of the sponge itself. When the ceraclea reaches adulthood and absconds from the sponge, it transports and disburses pieces, hence facilitating the formation of new sponge colonies.

Freshwater Sponge Habitats

Spongilla lacustris also known as freshwater sponges mostly prefer clear, shallow, waters. They are often spotted in rivers, streams, and slow-moving waters. They can be observed both safeguarded from the sun under logs and rocks, and on reeds and on rocks where there is greater exposure.

Freshwater Sponges Region of Formation

Freshwater sponges were reported to have first been found in the mid-1970s in Wolf Trap Creek at Wolf Trap National Park for the Performing Arts (WOTR), near George Washington Memorial Parkway (GWMP), and the Potomac River. However, no sponges have been seen in these spots since then. But, the freshwater sponge species Ephydatia muelleri (Mueller’s freshwater sponge) – one of the most common sponges in North America has been spotted in Prince William Forest Park (PRWI) in South Fork Quantico Creek since 2007. Mueller’s freshwater sponge was observed in profusion in light riffles or shallow pools in the second section of South Fork and the North Fork of Quantico Creek. In 2011, a second species of freshwater sponge, Dosilia radiospiculata, was observed in the Potomac River near locks 22 and 23 along the Ohio Canal.

Photosynthesis of Freshwater Sponge

Though not a plant, the necessity to photosynthesize has pushed these clear water sponges to develop into shapes not dissimilar to what is observed in the plant kingdom. Based on the clarity of the water, temperature, and light levels, sponge shapes span from prostate, creeping forms to upright branching compositions. Moreover, like plants, sponges can have reproduction both sexually and asexually. Since the water starts to cool in the fall, the sponges produce what is referred to as gemmules. These little bags of dormant cells are very hardy, withstanding pretty much anything the environment can make them exposed to. When the water starts to warm in the spring, the gemmules will develop into new sponge colonies. At the time of the warm summer months, sponges reproduce sexually. Males set out sperm into the water in anticipation that it will come into contact with receptive females. This is just like what we notice many wind-pollinated tree species do in the spring.