What are the classification of porifera?
The phylum Porifera has four classes, namely the Calcarea, Demospongiae, Hexactinellida and Homoscleromorpha. Exclusively marine, calcareous sponges predominantly inhabit shallow tropical waters.
What are the characteristics of Hexactinellida?
Overview. Hexactinellida are characterized by having siliceous hexactine (six-pointed) spicules, making them the second class within the major sponge group Silicea. They also construct two different body plans: sycon and leucon.
What are the 3 types of Porifera?
The three classes are: 1. Calcarea or Calcispongiae— (Calcareous Sponges) 2. Hexactinellida or Triaxonida or Hyalospongiae—(Glass Sponge) 3. Demospongiae.
How many species are there in the class Hexactinellida?
There are approximately 500 species of hexactinellids in two subclasses containing five orders, 17 families, and 118 genera. Hexactinellids have left the oldest fossil record of multi-cellular animals on Earth. Their triaxonic spicules are known from the Late Proterozoic of Mongolia and China.
What is the common name for Hexactinellida?
glass sponge, any of a class (Hexactinellida, also called Hyalospongiae, or Triaxonia) of sponges characterized by a skeleton that consists of silica spicules (needlelike structures) often united into a delicate geometric network—e.g., that of Venus’s flower basket (q.v.).
Where can you find a Demosponge?
Habitat. Most demosponges occur in all habitats at all depths. The Homoscleromorpha, Chondrosida, Agelasida, Dendroceratida, Halisarcida, and most Dictyoceratida occur mainly in the shallower parts of the oceans.
How do Demosponge reproduce?
The Demospongiae can reproduce both sexually and asexually. Methods of asexual reproduction include both budding and the formation of gemmules . In budding, aggregates of cells differentiate into small sponges that are released superficially or expelled through the oscula.
What is asconoid Syconoid and Leuconoid?
Body types: Sponges have three body types: asconoid, syconoid, and leuconoid. Asconoid sponges are tubular with a central shaft called the spongocoel. Leuconoid sponges lack a spongocoel and instead have flagellated chambers, containing choanocytes, which are led to and out of via canals.
What is the function of the amoebocytes?
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.
