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Sycon is a type of marine sponge that is found in shallow water. It is typically found adhering to shells and rocks and is a sedentary species. They are primarily found in temperate climates.
Systematic Position of Sycon
Phylum: Porifera
Class: Calcarea
Order: Heterocoela
Family: Sycettidae
Genus: Sycon
Sycons are normally small, ranging in height from 2.5cm to 7.5cm. These tube-shaped structures have a water vessel-like appearance. In some situations, they are also called crown sponges due to the arrangement of their spicules in the shape of a crown, while in others, they are called Q-tip or “Pineapple” sponges due to their likeness. Sycons are often delicate in appearance, structured in an asconoid system with a simple tube-like body wall devoid of folds.
Structure
Sponges exhibit a high degree of diversity, ranging from simple to complex creatures. They can, however, be classified as intermediate in terms of structural diversity. It has branching cylinders that are attached to the substratum at the basal end. Although it is firmly attached, the body is flexible. When these entities are examined more closely, they reveal the existence of numerous microscopic Ostia or inhalant pores. Each cylindrical branch’s free end has an orifice at the summit known as an osculum.
They are encircled by calcareous monaxon spicules or ocular fringes that act as a barrier to the admission of extraneous substances. The body is thin below the osculum, producing the collar region. Elevations on the body surface emerge as spicules (oxnotes), giving the appearance of bristles.
Habit and Habitat
Sycons live in isolation/colonialism. These marine organisms are found adhering to solid substrates such as coral and mollusk shells and rocks. Numerous species of sponges in this genus do not prefer to live in deeper water. Sycons appear to thrive in areas with slow-moving waves and low tides. They live on the underside of rocks in somewhat protected areas among hydroids, bryozoans, and other organisms. Certain species also grow as seaweeds.
Canal System
Sycons have an anatomical feature that is unique to them: a canal system. It uses watcher channels to penetrate the body. Sycon’s canal system is a Syncoid Stage I canal system, which is more advanced than the Asconoid canal system. The Ostia is connected to a core cavity by a network of canals; this central cavity is referred to as the spongocoel.
The human body is composed of a complex network of canals and pores, which together create the aquiferous or canal system. Choanoderm, Mesenchyme, and Pinacoderm make up the body wall.
Compositions of Canal System
Ostia – thin membranes line these cutaneous holes. These have two entrances, one for admission and another for exit. Myocytes control the shutting and opening of Ostia for water flow.
Sponogocoel/Paragastric or gastral cavity – The osculum connects to a huge central canal known as the spongocoel, which has been given several names. Pinacocytes, which are ectodermal flattened cells, line its wall. The osculum is surrounded by a layer of cells called myocytes that act as contractile sphincters. Spongocoel appears to be externally accessible via the osculum.
Radial canals — body wall evaginations. The spongocoel’s body wall lining is occasionally pushed out in the form of finger-like extensions called radial canals, the walls of which are coated with choanocytes. The radial canal’s outer end is closed, whereas the inner end is open and communicates with the spongocoel via the excurrent canal.
Incurrent canal — this tubular construction is located between two subsequent radial canals and is thus arranged alternately. Folds of the body wall that have been invaded. The inner end of the incurrent canal is blind, with pinacocyte-lined walls (flat and ectodermal). Between the radial and incurrent canals, the gastral cortex contains a thicker mesoglea. Ostia is positioned on the pore membrane and is surrounded by contractile myocytes that act as sphincters, preventing the openings from being blocked.
Between the radial and incurrent canals are prosopyles — tiny minute pores. Each of these is a Sycons intercellular channel that connects the incurrent canals to the radial canals. Porocytes, into which prosopyles open, are cylindrical and have a thick wall, with a nucleus near one end. It regulates water ingress and is extremely contractile.
Excurrent canals: These canals are used by radial canals to communicate with the spongocoel. They are wide and short, with pinacocyte-lined walls.
Apopyles – these are the apertures of the radial canals in spongocoel. They are surrounded by contractile myocytes.
Current Of Water ![Current Of Water in Sycon]()
Sycon’s water circulation follows this path. Water enters the body via an infinite number of Ostia along the external surface, each leading to the incurrent canal. Through prosopyle, water enters the radial canal from here. Water gushes into the spongocoel via the apopyles from the radial canal. Thus, the spongocoel is the common chamber into which all of the body’s radial canals open.
Finally, the spongocoel opens to the outside via an aperture called the osculum. As a result, water enters via multiple Ostia but escapes via the osculum, a single entrance. The planar pounding of choanocytes’ flagella generates a current in the radial canals that simultaneously sucks in and gushes out water.
Respiration
Between sponge cells and moving water, simple diffusion results in the exchange of gases.
The oxygen dissolved in the water diffuses into the cells, oxidising protoplasmic molecules and releasing the energy stored in ATP.
ATP is vital for providing energy to metabolically active cells.
Contractile vacuoles are thought to play a role in osmoregulation and excretion in the amoeboid cells of freshwater sponges.
Reproduction
Sexual and asexual reproduction are both observed. They generate a bud asexually and, in some cases, unique structures resembling freshwater sponge gemmules. Both ova and sperms are created in sexual reproduction from archaeocytes found in the mesoglea. Sperm cells have long tails that allow them to swim freely in the water stream, whereas ova are amoeboid-like and move via the mesoglea.
Sperm cells do not enter the ovum directly. When sperm cells enter the radial canal, they are captured by the choanocytes closest to the egg. The carrier cell is the choanocyte, which receives the sperm and ejects its flagellum and collar upon approaching the egg. The sperm eventually loses its tail and penetrates the egg. The initial phases of development occur within the mother sponge. Once the larva has completed its larval cycle, it gushes into the radial canal and subsequently to the outside.
Conclusion
Due to their numerous branching structure and lack of evident movement, early naturalists classified sponges as plants. Sponges’ animal nature, first described in 1755, was verified in 1765 by observations of their water currents and changes in the width of their central cavity openings. Sponges are unlike other animals in their form, function, and development; one of its most distinguishing characteristics is their lack of organs. Many zoologists see sponges as occupying a unique position within the animal kingdom, classifying them in the subkingdom Parazoa; nevertheless, molecular evidence suggests that sponges and more complex creatures developed from a common ancestor. They are almost certainly genuine animals that did not give rise to additional evolutionary lines.
