PORIFERA
Examples: Sponges, Sycon, Spongilla
Also known as sponges, Porifera fossils are one of the oldest known animal fossils, dating as far back as the Late Precambrian about 4.5 billion years ago. There are approximately 5,000 species of Porifera identified. Three specific groups of the Porifera phylum are; Hexactinellida, which consists of glass sponges who get there names due to there glassy appearance, and they often reside in the deep sea; Demospongia, are demo sponges, most sponges are members of this class; Calcarea are calcareous sponges, which is considered to be one of the simplest of all the Porifera phylum.
Also known as sponges, Porifera fossils are one of the oldest known animal fossils, dating as far back as the Late Precambrian about 4.5 billion years ago. There are approximately 5,000 species of Porifera identified. Three specific groups of the Porifera phylum are; Hexactinellida, which consists of glass sponges who get there names due to there glassy appearance, and they often reside in the deep sea; Demospongia, are demo sponges, most sponges are members of this class; Calcarea are calcareous sponges, which is considered to be one of the simplest of all the Porifera phylum.
CIRCULATORY SYSTEM
Sea sponges do not have a circulatory system, but instead utilize the constant flow of water for oxygen and nutrients. This specific process to obtain oxygen, nutrients and discard waste is known as a water based circulatory system. This is very different from a normal open or closed circulatory system found in many animals that have cardiac systems. Sponges do not have hearts, which usually pump molecules and materials, such as oxygen through vessels in the body. Instead, small pores called ostia open up, allowing the cell tails on the surface to create a water current. This current transports the sea water, molecules and nutrients it carries throughout the sponge.