Leucosolenia

Leucosolenia, or Leucoselenia, is a genus of tubular branched sponges that belongs to the Calcispongiae family (phylum Porifera). The broad genus comprises most of the asconoids, structurally the simplest sponges, and is represented by various species found in tidal pools and on wharves. Most Leucosolenia species are only 2.5 centimetres (one inch) long. They form a colony of thin individuals linked by a shared stolon, a rootlike structure that also connects the group to the ground or another surface. Water enters the animal's internal chamber (spongocoel) through multiple tiny holes and exits through one big aperture at the tip, the osculum. Flagella linked to choanocytes produce the water stream. The cells that line the spongocoel are called choanocytes (that is, the central cavity of the sponge). Pinacocytes are thin, flat cells that make up the outer body wall. The mesoglea, a jellylike matrix between the two cell layers, generally contains freely moving cells (amoebocytes) and skeletal spicules structured like thin three- or four-pointed stars. Spicules are generated by particular amoebocytes and offer support for the body tube.

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Leucosolenia

Leucosolenia is a calcareous sponge genus that belongs to the Leucosoleniidae family. This genus' species are generally found in groups of curving vases that are up to 2 cm long and finish in an osculum. The overall form has been compared to a little bunch of bananas. They're most commonly seen in tidal pools, crowded at the base of seaweeds or on rocks, and come in a range of colours, the majority of which are very pale. It has an asconoid canal system. The colony is made up of a few basic vase-like, cylindrical individuals, each with an osculum and irregular horizontal tubes joining them at the base. Both asexual and sexual reproduction is possible for Leucosolenia.

Asexual reproduction occurs by budding, while sexual reproduction occurs through the creation of gametes, such as eggs and sperms. Because both gametes are produced in the same individual's body, Leucosolenia is hermaphrodite.

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Habitat and Distribution of Leucosolenia

Leucosolenia is a colonial marine sponge that is tiny and finely branching. Leucosolenia is a common genus that lives in tide pools and on wharves, attached to the substrate. It only grows in the shallow water below the low tide mark on seashore rocks where there is a lot of wave activity, and not in calm water. Leucosolenia is common along the northern Atlantic coast, and it is thought to be extremely sensitive to environmental factors. Around 100 species of Leucosolenia have been found in various waters around the world. L. botryoides, L. complicate, and L. variabilis, on the other hand, are common species.

New individuals are generally born as free-swimming flagellated larvae from amoebocyte eggs. These larvae are released through the parent's osculum. They eventually metamorphose into microscopic sponges after permanently sticking themselves to new surfaces. Some leucosolenids, such as L. botryoides, can also reproduce through budding, which is a process in which the parent body's fingerlike extension breaks off. When the extension is attached to a new site, the tip of the extension becomes the lower end of the new individual.

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Leucosolenia Diagram

The Leucosolenia colony is a whitish-yellow colour. The colony of Leucosolenia's simplest species is made up of a few basic vase-like, cylindrical individuals, each terminating in an osculum and connected at their bases by irregular horizontal tubes. The majority of species are more complicated, consisting of a labyrinth of branching tubes from which a few larger upright cylinders with an osculum emerge.

Finally, in most species, the outermost tubes fuse to form a false surface or pseudoderm, leaving a few large openings or pseudo pores so that the sponge appears solid and mimics a higher kind of sponge; however, sections reveal the internal network of ascon tubes. Each colony tube may grow to be up to 25 mm tall and produce several buds. At the summit of each major tube is an opening called an osculum, which opens to the outside. The spongocoel or paragastric cavity is the tube's cavity. 

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Body Wall

The pinacoderm, an outer epidermis, and the choanoderm, an inner endodermis, are separated by a jelly-like non-cellular layer of mesenchyme or mesogloea, which encloses a central hollow, the spongocoel. Each tube's wall is perforated with many pores through which water enters the spongocoel and escapes through the osculum. 

1. Pinacoderm

The outer epidermis is made up of pinacocytes (Greek: pinako = plank; kytes = cell), which are thin, scale-like, flattened cells that form a single layer of cells termed the pinacoderm. This layer serves as the tube's exterior protective layer. A pinacocyte is characterised by thin, strongly contractile margins and a central bulging nucleus.

2. Choanoderm

The inner epithelium, also known as gastrodermis, is made up of a single layer of choanocyte (Greek: choane = funnel; kytos = cell) cells that line the spongocoel. A choanocyte is an oval cell with a flagellum that emerges from the basal granule and a contractile transparent protoplasmic collar at its base. Choanocyte nuclei are found near the cell's base. The beating of choanocyte cells' flagella maintains a water current in the sponge's body.

3. Mesenchyme or Mesogloea

Between the pinacoderm and the choanoderm is the mesenchyme layer.

Mesenchyme is a thin layer that resembles a gel. Choanocytes produce it, and it keeps the skeletal components of CaCO₃ known as spicules or sclerites in place. Amoebocytes, which are amoeboid cells, are found in the mesenchyme and roam freely. In nature, these cells contain RNA and are self-replicating.

These cells are totipotent in that they may give birth to a variety of cells, including pinacocytes, choanocytes, colonocytes, sclerocytes or scleroblasts, and reproductive cells. The spicules are needle-like crystalline spicules known as monaxons, tetraxons (four rays), or triaxons. Scleroblast cells separate the spicules, which stay lodged in the mesenchyme, while some monaxon spicules protrude from the pinacoderm. A sparse border of monaxon spicules surrounding the osculum. 

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Physiology of Leucosolenia

Except for changes in the porocytes, no mature sponge is capable of locomotion, and some are completely devoid of contractile powers. Most have local contractile capabilities that appear to be limited to within 3 to 4 mm of the strong stimulus site. When stimuli are delivered to the osculum area, reactions are most evident. All reactions are gradual, and it takes one to several minutes for them to become visible. Because sponges lack sensory or nerve cells, the contractile responses described above are direct responses to stimuli. In typical circumstances, all of a sponge's apertures (Ostia and oscula) are wide open, and water rushes in via the incurrent openings (Ostia) and out through the osculum. The beating of the flagella of the choanocytes causes the water currents. This flow transports food and allows for gaseous exchange and the removal of metabolic wastes. Because of the sponge's structure, water flows slowly through the choanocyte regions.

Reproduction of Leucosolenia

Leucosolenia Reproduces both Asexually and Sexually.

1. Asexual Reproduction

By budding, Leucosolenia reproduces asexually. Leucosolenia budding produces new horizontal branches that grow over rocks and other substrata, resulting in erect vase-shaped individuals. The tips of the upright branches burst through as an oscula when they reach a suitable size. Leucosolenia also has a remarkable ability to regenerate. Any fragment of Leucosolenia can develop into a whole person. This is a lengthy process, and it might take months or even years to reach the required size.

2. Sexual Reproduction

Gametes, such as eggs and sperms, are formed during sexual reproduction.

Leucosolenia is hermaphrodite because both gametes are produced in the same individual's body, despite the absence of gonads. The gametes, on the other hand, are created by the differentiation (or gametogenesis) of amoebocyte cells. Internal cross-fertilization takes place. With the help of the water current, sperm are pulled into Leucosolenia's body and fertilise the eggs. Metchnikoff (1879) and Minchin (1879) both documented the progression of Leucosolenia (1896).

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Development of Leucosolenia

Coeloblastula is an oval hollow blastula formed by equal and holoblastic cleavage of the fertilised egg. Except for a clump of rounded non-flagellated cells at the posterior pole, the coeloblastula is made up of thin flagellated cells. These are thought to be archaeocytes, which give rise to all subsequent archaeocytes in the sponge. These, together with nearby flagellated cells (which lose their flagella as a result), wander into the interior, filling it with a mass of cells. As a result, the larva develops into a stereo gastrula or parenchymula with an amoeboid cell mass inside.

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For several hours, the parenchymula swims freely. It then connects to the anterior pole and transforms into a flat plate with an uneven shape. The epidermis (pinacoderm) and mesenchyme are formed when amoeboid cells (interior cells) move to the exterior surface. As a result, the flagellated cells are enclosed and converted into choanocytes. Spicules are secreted after a central spongocoel appears, an osculum breaks through, and a central spongocoel emerges. The larva transforms into an adult asconoid sponge after a few days of attachment.

Leucosolenia Species

The Genus Leucosolenia Includes the Following Species.

• Leucosolenia aboralis

• Leucosolenia albatrossi 

• Leucosolenia arachnoides

• Leucosolenia australis 

• Leucosolenia botryoides

• Leucosolenia brondstedi Van Soest & Hooper

• Leucosolenia cervicornis

• Leucosolenia clarkii

• Leucosolenia complicata

• Leucosolenia corallorhiza

• Leucosolenia cyathus

• Leucosolenia discoveryi Jenkin

• Leucosolenia echinata Kirk

• Leucosolenia eleanor Urban

• Leucosolenia eustephana Haeckel

• Leucosolenia falklandica Breitfuss

• Leucosolenia feuerlandica Tanita

• Leucosolenia fragilis

• Leucosolenia gegenbauri

• Leucosolenia goethe 

• Leucosolenia hispidissima

• Leucosolenia horrida

• Leucosolenia incerta Urban

• Leucosolenia kagoshimensis 

Conclusion

Leucosolenia is a genus of tubular branched sponges. Most species are 2.5 centimetres (1 inch) long and form a colony of thin individuals linked by a rootlike structure that also connects the group to the ground or another surface. . The Leucosolenia colony is a whitish-yellow colour. L. botryoides can grow up to 25mm tall. It's found in the, which is similar to 'Leucosolea' from Japan. The inner epithelium is made up of a single layer of choanoderm cells that line the sponges' body. It contains amoeba.5 (Cholos) and caiman, which can be found in Japan. Leucosolenia reproduces both sexually and asexually. By budding, the sponge produces horizontal branches that grow over rocks and another substrate. The tips of the upright branches burst through as an oscula when they reach a suitable size. This is a lengthy process, taking months or even years to reach the required size.