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=What are Sponges?= | =What are Sponges?= | ||
Sponges, from the Latin pore bearers, are very primitive animals of the phylum Porifera, more precisely they are the first multicellular animals. They evolved very early from colonial protists. Their ancestors are the choanoflagellates (group of free-living | Sponges, from the Latin pore bearers, are very primitive animals of the phylum Porifera, more precisely they are the first multicellular animals. They evolved very early from colonial protists. Their ancestors are the choanoflagellates (group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals). There are between 8'000 and 9'000 species of sponges, depending of the textbook.<br>They are '''invertebrates''', which are animals without backbones. There exist different sponges of different forms and different shapes, including tubes, fans, cups, cones, blobs, barrels, and crusts. | ||
*see '''Appendix Sponges 1''' | *see '''Appendix Sponges 1''' | ||
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==What are the main characteristics of Sponges?== | ==What are the main characteristics of Sponges?== | ||
Sponges are loosely organized and lack true tissues. Their sizes are from a few millimeters to more than 2 meters in diameter. They don't have any symmetry | Sponges are loosely organized and lack true tissues. Their sizes are from a few millimeters to more than 2 meters in diameter. They don't have any symmetry | ||
The body of a sponge looks similar to a vase pierced with small holes and pores. It has thousands of pores. Water is drawn through the little pores into a central cavity, the spongocoel, then flows out the sponge through a larger opening, the osculum. In this process, they collect small particulate matter and tiny planktons, by the trapping action of the choanocytes, which are collar cells. That's why we call them filter feeders. Sponges do not have nervous, digestive or circulatory systems. As adults, sponges are sessile. That means that they are permanently attached to a substrate and are unable to move on their own. | The body of a sponge looks similar to a vase pierced with small holes and pores. It has thousands of pores. Water is drawn through the little pores into a central cavity, the spongocoel, then flows out the sponge through a larger opening, the osculum. In this process, they collect small particulate matter and tiny planktons, by the trapping action of the choanocytes, which are collar cells. That's why we call them filter feeders. Sponges do not have nervous, digestive or circulatory systems. As adults, sponges are sessile. That means that they are permanently attached to a substrate and are unable to move on their own. | ||
{{co|good. Maybe you could create an Appendix document showing the main characteristics of Sponges}} | {{co|good. Maybe you could create an Appendix document showing the main characteristics of Sponges}} | ||
[[Utilisateur:Pierre.brawand|Pierre.brawand]] | [[Utilisateur:Pierre.brawand|Pierre.brawand]] | ||
==Where do Sponges live?== | ==Where do Sponges live?== | ||
Of the 9'000 or so species of sponges, only about 100 live in fresh water, the rest are marine. | Of the 9'000 or so species of sponges, only about 100 live in fresh water, the rest are marine. | ||
=What are Cnidarians?= | =What are Cnidarians?= | ||
Version du 17 janvier 2011 à 11:31
What are Sponges?
Sponges, from the Latin pore bearers, are very primitive animals of the phylum Porifera, more precisely they are the first multicellular animals. They evolved very early from colonial protists. Their ancestors are the choanoflagellates (group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals). There are between 8'000 and 9'000 species of sponges, depending of the textbook.
They are invertebrates, which are animals without backbones. There exist different sponges of different forms and different shapes, including tubes, fans, cups, cones, blobs, barrels, and crusts.
- see Appendix Sponges 1
What are the main characteristics of Sponges?
Sponges are loosely organized and lack true tissues. Their sizes are from a few millimeters to more than 2 meters in diameter. They don't have any symmetry The body of a sponge looks similar to a vase pierced with small holes and pores. It has thousands of pores. Water is drawn through the little pores into a central cavity, the spongocoel, then flows out the sponge through a larger opening, the osculum. In this process, they collect small particulate matter and tiny planktons, by the trapping action of the choanocytes, which are collar cells. That's why we call them filter feeders. Sponges do not have nervous, digestive or circulatory systems. As adults, sponges are sessile. That means that they are permanently attached to a substrate and are unable to move on their own.
good. Maybe you could create an Appendix document showing the main characteristics of Sponges Pierre.brawand
Where do Sponges live?
Of the 9'000 or so species of sponges, only about 100 live in fresh water, the rest are marine.
What are Cnidarians?
Cnidarians (phylum Cnidaria) are mostly marine species (more than 10'000). The Cnidaria are the oldest of the true metazoan phyla The name Cnidaria comes from the Greek word "cnidos" which means stinging nettle. All the Cnidaria are aquatic and nearly all are marine.
What are the main characteristics of Cnidarians?
They are two different forms of Cnidarians body: Polypoid Shape or Medusoid Shape.
The polypoid is the shape of corals and anemones. Its characteristics are the mouth and the tentacles facing up and the other side is anchored to a colony of the same aspect: for example, a coral reef.
Medusoids are jellyfish. They are free swimmers and their tentacles and mouth are pointed down (the opposite of polypoids)
Cnidarians have a mouth and a simple digestive system at the center of their tentacles, that is the reason why they are considered as animals and not plants. They have a radial symmetry. All cnidarians use tentacles which have stinging cells to subdue and capture food. They generally eat small planktonic animals.
- see Appendix Cnidarians 1
Where do Cnidarians live?
They live under water. Some Cnidarians live in the oceans and seas, and a few live in freshwater. But they mostly live in saltwater or oceans.
OK... good start but you should now produce more information...[ [Utilisateur:Pierre.brawand|Pierre.brawand]]
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