The Porifera Phylum is most commonly known as sponges. There are over 9,000 different types of sponges and a vast majority of these live in salt water but a small percentage do live in fresh water. Porifera are in the parazoa branch of the animal kingdom because they are formed in loose bundles of cells instead of specialized layers and tissues. The basic body plan of sponges is double cell walls with a spongoceal in between the layers. Porifera are divided in to three main classes by the chemical structure of their skeletal system. There is the Calcarea, Hexactinellida, and Demosphongiae
Yellow Calcareous Sponge
The Carcarer is one of the main classes of porifera. Its skeletal structure is composed of calcium carbonate and its interior spongoreal is making of caloblast. All calcarer live in a salt water environment. Many of these spongers are only 10 cm in length. However these spongers are able to take many different forms such as conoid, which is indefinite shape, syconoind that is tube shaped, and leuconoid that is flagellated in shape.
Hexactinellida sponges are sponges with a skeletal structure made of silica. Hexactinellida sponges are more often referred to as glass sponges. Glass sponges often have a cup like shape. It also has an endoskeleton consisting of silicoblast. Class sponges are vary uncommon and are only found in the deep depths of the ocean. These creatures range from 10 to 30 cm in height. The body is mostly symmetrical and has 1 large open cavity in the center an example of the glass sponge is the bowl sponge shown here
Demosponges are the largest of the sponge classes and contain the most diversity among sponges. The skeletal system of demosponges is made of silica and spongein fibers. The endoskeleton is made of silicablasts. Many of these animals have a leveomoid structure that is flagellated shaped. This large species can grow well over a meter in with an example of a large demosponge is the barrel sponge.