What are the different types of spicules found in sponges?

On the basis of the material they are formed of, spicules are of two types: Calcareous, made of calcium carbonate and characteristic of the class Calcarea and Siliceous, made of silica and characteristic of the class Hexactinellida.

What are the three types of spicules?

Based on the number of axis present in the rays spicules may be of three types: monoaxon, triaxon and polyaxon. Monaxon: These spicules grow along a single axis. These may be straight needle-like or rod-like or may be curved. Their ends may be pointed, knobbed or hooked.

What are spicules and its types?

First, spicules are of two general kinds—megascleres and microscleres. The spicules are further classified according to the number of their axes and rays. Words designating the number of axes end in axons, those referring to the number of rays end in actine or actinal.

How are spicules used to identify sponges?

Spicules are the structural components of a sponge, or the “bricks,” and the shapes, sizes, and composition are unique for each species. Together, you can look at these features under a microscope to make a positive identification. Spicules are composed of either Calcium or Silica.

Where are spicules in sponges?

Spicules are microscopic structures of hard crystal material with fantastic shapes unique to the different species of sponge. They are part of the skeleton that helps give the sponge its shape.

What kind of skeletons are found in sponges?

Sponges have an internal skeleton that gives them support and protection. An internal skeleton is called an endoskeleton. A sponge endoskeleton consists of short, sharp rods called spicules (see Figure below). Spicules are made of silica, calcium carbonate, or spongin, a tough protein.

What are Amoebocytes in sponges?

In sponges, amebocytes, also known as archaeocytes, are cells found in the mesohyl that can transform into any of the animal’s more specialized cell types. In older literature, the term amebocyte is sometimes used as a synonym of phagocyte.

Are sponges Cephalized?

Sponges have no particular symmetry; they are not radially or bilaterally symmetrical. Cephalization means having a head. Cephalization only occurs in bilaterally symmetrical animals.

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.

Where are the spicules in a sponge?

What phylum are spicules?

phylum Porifera
The siliceous sponges form a major group of the phylum Porifera, consisting of classes Demospongiae and Hexactinellida. They are characterized by spicules made out of silicon dioxide, unlike calcareous sponges….Siliceous sponge.

What function do spicules have?

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.