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 are spongin and spicules?
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. Generally, species are identified based on the presence or absence of spongin in a sample.
Do all sponges have spongin?
Although the majority of sponges live in marine habitats, one family, the Spongillidae, is found in fresh water. Calcarea, Hexactinellida, Demospongiae, and Homoscleromorpha make up the four classes of sponges; each type is classified based on the presence or composition of its spicules or spongin.
Is spongin hard or soft?
Spongin is the flexible material that makes up the body wall of the sponge, while spicules are hard, spiny secretions that help to provide a reinforced structure.
What is the function of spongocoel?
The spongocoel is lined by a variety of cell types, each having a unique function: porocytes – line the pores of the sponge and are the structure through which water is taken into the organism. choanocytes – exhibit flagella that create inward currents of water for the sponge’s stationary filter feeding mechanism.
How are spongin fibers formed?
Development of spongin
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 is Gemiul?
Gemmules are internal buds found in sponges and are involved in asexual reproduction. It is an asexually reproduced mass of cells, that is capable of developing into a new organism i.e., an adult sponge.
What is the job of the Archaeocyte?
Archaeocytes ingest and digest food caught by the choanocyte collars and transport nutrients to the other cells of the sponge. In some sponges, archaeocytes develop into gametes.
What class is a sponge?
Class Demospongiae: spicules are made of silicon dioxide and/or spongin fibres, most sponges belong to this class, species vary greatly in form and size, many may develop a secondary deposit of silica on its body.
What is the function of mesohyl?
The mesohyl acts as a type of endoskeleton, helping to maintain the tubular shape of sponges.
What do Poriferans eat?
The Porifera are primarily filter feeders, utilizing food particles suspended in the water and captured by the choanocytes. Food particles consist essentially of bacteria, other microorganisms, and particles of organic debris; sponges also probably absorb dissolved organic substances.
Why are Poriferas called sponges?
The phylum name Porifera means pore-bearing. Sponges take their name from small holes that cover their bodies. The history of life is written on the bodies of the animals that previously inhabited and continue to inhabit earth.
What is the lifespan of a sponge?
Sponges in temperate regions live for at most a few years, but some tropical species and perhaps some deep-ocean ones may live for 200 years or more. Some calcified demosponges grow by only 0.2 mm (0.0079 in) per year and, if that rate is constant, specimens 1 m (3.3 ft) wide must be about 5,000 years old.
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 role do Amoebocytes play?
Amoebocytes have a variety of functions: delivering nutrients from choanocytes to other cells within the sponge, giving rise to eggs for sexual reproduction (which remain in the mesohyl), delivering phagocytized sperm from choanocytes to eggs, and differentiating into more-specific cell types.
What is spongocoel 11?
Spongocoel is a large, central cavity of sponges from where water enters. The spongocoel is surrounded by a lining of cells called choanocytes, containing a central flagellum that is surrounded by microvilli.
What are Incurrent canals?
[in′kər·ənt kə′nal] (invertebrate zoology) A canal through which water enters a sponge.
What is spongocoel in which phylum do you find?
Spongocoel is found in phylum Porifera. porifera means”pore-bearing” & refers to numerous pores and channels that permeate a sponge’s body.
