The exoskeleton of sponges (so, the parts that you see) are composed of a mixture of spongin and/or spicules. Spongin is a modified type of collagen protein, and forms the “fibers” or “mortar” that hold spicules together. … Spicules are composed of either Calcium or Silica.
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How are spicules and spongin similar and different from one another what are the functions of these spicules and spongin?

Spicules are formed by carbonates of lime or silica in the form of needle like pieces. Spongin fibres are composed of a silk-like scleroprotein. The spicules constitute major part of skeletal system, which are secreted by special mesenchymal cells called scleroblasts.

What are Triaxon spicules?

Triaxon: Triaxon spicule has three axes that cross one another at right angles to produce six-rays. These are found only in class Hexactinellida. Tetraxon spicules consist of four rays radiating from a common point. … They are common among the glass sponges.

What are the functions of these spicules and spongin?

Besides supporting sponge cells, spicules can help larvae stay buoyant while in the plankton or reach the bottom at settlement, enhance reproduction success, or catch prey. Conversely, the role of spicules and skeletons in deterring predation has not been demonstrated.

Do all sponges have the same types of spicules and/or spongin?

The presence and composition of spicules and spongin are the differentiating characteristics between the classes of sponges. Demosponges, which contain spongin and may or may not have spicules, constitute about 90% of all known sponge species, including all freshwater ones, and have the widest range of habitats.

What is the function of spongin?

Spongin, a modified type of collagen protein, forms the fibrous skeleton of most organisms among the phylum Porifera, the sponges. It is secreted by sponge cells known as spongocytes. Spongin gives a sponge its flexibility.

What is the function of mesohyl?

The mesohyl acts as a type of endoskeleton, helping to maintain the tubular shape of sponges.

What are spongin fibers?

Spongin is a modified type of collagen protein, and forms the “fibers” or “mortar” that hold spicules together. Generally, species are identified based on the presence or absence of spongin in a sample.

How are spongin fibers formed?

Spongin fibers are secreted by flask-shaped mesenchyme cells called as spongioblast cells. During the development the spongioblast cells are arranged in the rows and the spongin rods secreted by them are fused with the neighboring cells to form a long fiber.

What are the function of spicules?

Tiny spicules help make the sponge’s body rigid. They interlock to provide support like the bones in familiar animals. Animation helps visualize how the elaborate shapes of the microscopic spicules could help give the sponge’s body structure.

What are the different type of spicules found in sponges?

  • Acanthostyles are spiny styles.
  • Anatriaenes, orthotriaenes and protriaenes are triaenes – megascleres with one long and three short rays.
  • Strongyles are megascleres with both ends blunt or rounded.
  • Styles are megascleres with one end pointed and the other end rounded.
What is the nature of fertilization in Poriferans?

The fertilization of an egg by a spermatozoan is peculiar in sponges in that a spermatozoan, after its release from a sponge, is carried by the water current until it is captured by a specialized flagellated cell called a choanocyte, or collar cell, in another sponge.

What is the Osculum in a sponge?

The osculum (plural “oscula”) is an excretory structure in the living sponge, a large opening to the outside through which the current of water exits after passing through the spongocoel. Wastes diffuse into the water and the water is pumped through the osculum carrying away with it the sponge’s wastes.

What's the difference between Ostia and porocytes?

Once through the pores, water travels down canals. The opening to a porocyte is a pore known as an ostium. In sponges, like Scypha, there are some cells that have an intracellular pore. These cells are known as porocytes.

Why are Ostia important to sponges?

Scattered among the pinacoderm are the ostia that allow entry of water into the body of the sponge. These pores have given the sponges their phylum name Porifera—pore-bearers. In some sponges, ostia are formed by porocytes, single tube-shaped cells that act as valves to regulate the flow of water into the spongocoel.

What is the function of Ostia and Osculum in the body of a sponge?

Ostia are tiny pores present all over the body of sponges. its function is to let the water, along with desire nutrient flows interior of the sponges. Osculum is a excretory structure opening to the outside through which current of water exist after passing through the spongocoel.

Which of the following describes a Choanocyte?

Choanocytes (also known as “collar cells”) are cells that line the interior of asconoid, syconoid and leuconoid body types of sponges that contain a central flagellum, or cilium, surrounded by a collar of microvilli which are connected by a thin membrane.

How do you differentiate a siliceous Spicule from a calcareous Spicule?

Calcareous spicules are needle-like, or stellate with three or four radiating needle-like rays. Siliceous spicules are needle-like, stellate with three to many rays, or of special symmetrical or irregular shapes (cf. Figs.

What is Mesohyl or mesenchyme?

The mesohyl, formerly known as mesenchyme or as mesoglea, is the gelatinous matrix within a sponge. … These polypeptides form the extracellular matrix which provides the platform for specific cell adhesion as well as for signal transduction and cellular growth.

What is the difference between Mesohyl and Mesoglea?

The main difference between mesoglea in cnidarians and mesohyl in poriferans is that mesoglea in cnidarians mainly composes of water and several substances including fibrous proteins, like collagen and heparan sulfate proteoglycans, whereas mesohyl in poriferans is a gelatinous matrix, mainly composing of collagen, …

What characteristics of the animal kingdom are present in the porifera?

  • These are pore-bearing multicellular animals.
  • The body has no organs.
  • They exhibit holozoic nutrition.
  • The body is radially symmetrical.
  • They can regenerate their lost parts.
Why are Poriferas called sponges?

The name porifera means ‘pore bearer’ in Latin (a pore is a tiny hole). A sponge’s body is covered by a skin, one cell thick. This skin has lots of small pores and a few large openings. … These collar cells pump water through the entire sponge and filter out food for the sponge cells to eat.

What is the skeleton of Poriferans made?

The skeleton of poriferans is made up of spicules or spongin fibres.

Which spicules are present in sycon?

SYCON SPONGE – SKELETON The body of sycon sponge is made by outer dermal layer and inner gastral layer In between these two layers mesenchyme is present. This mesenchyme contains amoebocytes. The scleroblasts secrete spicules which from the skeleton of the sycon body. These spicules are made by calcareous substance.

What is the Pinacocytes function?

Function. Pinacocytes are part of the epithelium in sponges. They play a role in movement (contracting and stretching), cell adhesion, signaling, phagocytosis, and polarity. Pinacocytes are filled with mesohyl which is a gel like substance that helps maintain the shape and structure of the sponge.

Do Poriferans have muscles?

Sponges don’t have internal organs. They don’t have muscles, a nervous system, or a circulatory system. Their walls are lined with many small pores called ostia that allow water flow into the sponge.

How do spicules help sponges survive?

Spicules act as a skeleton to give support & shape to the sponge, including keeping the pores and osculum open. Their sharp point may also help protect the sponges from being eaten by predators. … Their sharp point may also help protect the sponges from being eaten by predators.

How do humans use cnidarians quizlet?

Humans use cnidarians for aquariums and to study for medical purposes. … Humans place the survival of cnidarians in danger through reclamation, pollution, tramplings, and poaching.

What are Porocytes and their functions?

In the Calcarea, the outer surface of the body also contains flattened granular cells called porocytes because they contain the pores needed to allow water into the sponge. The porocytes can contract, thus closing the pores during unfavourable environmental conditions.

Which class of sponges has spicules composed of the protein spongin?

Species within the class Hexactinellida are also referred to as glass sponges because their skeletons consist of spicules made of silica, the primary component of glass. The skeletons of the class Desmospongia are composed of spicules made up of silica and skeletal fibers made from spongin, a type of collagen protein.

What is the habitat of Poriferans?

The phylum Porifera comprises the sponges. Sponges are simple invertebrate animals that live in aquatic habitats. Although the majority of sponges are marine, some species live in freshwater lakes and streams. They are found in shallow ocean environments to depths as great as five kilometers (km).

How tall is a sponge?

Most sponges are only a few centimetres in size, but some urn-shaped or shapeless ones are less than a centimetre (0.4 inch); others, shaped like vases, tubes, or branches, may be one to two metres (3.3–6.6 feet) tall, and broad rounded masses may be one to two metres in diameter.

What cells line the Ostia of sponges?

In some sponges, ostia are formed by porocytes, single tube-shaped cells that act as valves to regulate the flow of water into the spongocoel.

Is Demospongiae an Asconoid?

They are small, usually vase shaped and asconoid, syconoid, or leuconoid in structure. Glass sponges (Clade or Class Hexactinellida) are mostly deep sea forms. … Clade (Class) Demospongiae contains most of the sponge species. Spicules are siliceous, but not six-rayed.

What features do Choanoflagellates have in common with choanocytes in sponges?

There are striking physical resemblances between choanoflagellates and certain animal cells, specifically the feeding cells of sponges, called choanocytes. Sponge choanocytes also have a flagellum and possess a collar of filaments for trapping food. Similar collars have been seen on several kinds of animals cells.

What is Prosopyle and Apopyle?

Water enters the sponge through these pores and moves into the incurrent canal. Water leaves this area to enter the. radial canal (area of choanocytes) via the prosopyle – (a porocyte cell) Water leaves the area of choanocytes via a much larger pore, made by many cells = the apopyle.

What are Incurrent canals?

[in′kər·ənt kə′nal] (invertebrate zoology) A canal through which water enters a sponge.

What is the function of Archaeocytes in a sponge?

Functions. Cellular differentiation is an essential function of the archaeocyte. All specialized cells within the sponge have its origins with the archaeocyte. This is especially important in reproduction as the sex cells of the sponge in sexual reproduction are formed from these amoeboid cells.