How and what does a sponge eat

The sponges are living animals that live in the water. They are stuck to the floor in the oceans, sea, and rivers.

They are known as Porifera. The Poriferans are simple multi cellular animals. There are about to 10, of species of Porifera that are known today. Out of them only species live in fresh water. The rest of the sponges dwell in salt-water. Sponges are very primitive creatures that evolved around million years ago 1. There are many different types of sponges all over the world. Some of these sponges are very colorful and beautiful 1.

Sponges are the first and most simple members of Metazoa in the ancestral lineage of animals Dawkins Today the rest of the Metazoans are considered to belong to Eumetazoa. Some molecular taxonomists think that there are two lineages of sponges, one more closely related to other more complex Metazoans than the other. People often think of sponges as plants, rather than being animals. This misconception is due to some of the characteristics of the Porifera Dawkins Like plants they do not move, i.

They stay put in one place stuck to the bottom of the water- either salt or fresh. Also, they don't have muscles. Like plants they move at the cellular level Dawkins Sponges are multi-cellular. They are known be diploblast, which means having two layers of cells Dawkins As an adult they may have multiple cell layers, but initially they all arise from the two layers that were present in the early embryo Dawkins Most are sponges are asymmetrical, though some of them exhibit radial symmetry Dawkins The typical body form of a sponge consists of a hollow pitcher surrounded by lots of small holes and opens up on the top with a big hole.

Sponges do not have a coelom. A coelom is the cavity within the body in which the intestines, lungs, heart, kidney, etc. The body cavity of sponges is large, it is open to the outside world, and it enables the sponge to consume food Dawkins Sponges do not have any internal organs or a nervous system.

Their skeleton is made of tiny, needle-like splinters, or a mesh of protein called spongin 2 Most of the Demospongiae are made of spongin. Some of the sponges are made of both spicules and spongin.

Bath sponges are made of calcereous or siliceous spicules, and they are therefore soft to the touch. Most of the bath sponges are Demospongiae 2. Although not scientifically classified so, sponges exist into two basic groups based on body structure: encrusting and free-standing.

Encrusting sponges have amorphous bodies. They cling to surfaces like rock and other hard surfaces, where a carpetlike layer forms on them. Encrusting sponges make complicated webs to filter nutrients out of the water, spreading like moss over surfaces. Free-standing sponges are more complicated body forms than encrusting sponges. They can develop in a variety of shapes, like tall tubes and cupped vases. The largest free-standing sponges are barrel sponges, which can stand taller than 6 feet.

Sponges can grow this big only when enough food exists in the environment to support such large bodies. Barrel sponges often grow in deep waters rich with ocean life. In the deep sea, the sponge diet is different. The harp sponge Chondrocladia lyra is the first species of carnivorous sponge identified by marine researchers, about 20 years ago.

Harp sponges are known to have between two and six vanes radiating out from a center -- those with more vanes may exist.

Each vane has vertical branches lined with hooks. Spicules vary in shape from simple rods to three-dimensional "stars" with up to six rays. Some sponges also secrete exoskeletons that lie completely outside their organic components whilst others, e. Spongia officinalis , the bath sponge, have no spicules at all. Sponges do not have a nervous, digestive or circulatory system. They rely on keeping up a constant water flow through their bodies to obtain food and oxygen and to remove wastes. Sponges have a unique feeding system among animals.

Instead of a mouths they have tiny pores ostia in their outer walls through which water is drawn. Cells in the sponge walls filter food from the water as the water is pumped through the body and the osculum "little mouth". The flow of water through the sponge is in one direction only, driven by the beating of flagella which line the surface of chambers connected by a series of canals.