Phylum Porifera: Sea Sponge Characteristics, Reproducution and More!
Phylum Porifera - Sea Sponge
The phylum (phylum is a classification of animals below kingdom and above class) Porifera is an amazing and diverse set of species. There are 5,000 different species in the phylum Porifera and they are commonly known as the sponge or sea sponge. There are 900 fresh water sponges and the rest are salt water.
One of the main characteristics about sponges is that they are all filter feeders. Even very small sponges (those that are only 10 cm long) are able to filter over 100 liters of water each day. They are able to receive nutrients from the water that they filter through their pores.
Sponges have body structures optimized for filter feeding. Their body structure is fairly simple in comparison to other more complex creatures, but their structure is perfect for filter feeding.
Sponge Body Structure
A sponge has three main layers to their body structure. The outer layer is a layer of flattened epidermal cells; the second is a semi-fluid matrix and the inner layer is a layer of flagellated collar cells. One other important part of the body structure of the sponge is the osculum, which is the opening at the top of the sponge.
Lets look at these three layers in laymen’s terms:
Flattened Epidermal Cells
This layer is the protective layer of the sponge. It is the stiff outer layer that protects the inner layers from injury. This layer has very many small holes all about its body called pores. These pores allow water to flow into the rest of the sponge.
Flagellated Collar Cells
The layer of Flagellated Collar Cells is the most interesting of the three layers of sponges. This collar layer is flagellated, which means that they have flagellum. Flagellums are a specialized part of certain cells. They are a tail like piece that sticks out of the cell and usually assists in locomotion of the cell.
In a sponges collar layer, a Flagellum works a bit differently. Instead of moving the cell, they act in locomotion, but they are moving the water surrounding the cells instead of the cells themselves. These small parts of the cell are constantly whipping their tails in a circular motion, which causes a current of water to flow into the cup like portion of the sponge.
The water seeps through the pores and as it flows through the three layers, it takes in nutrients.
Sponges reproduce extremely effectively: They are able to reproduce sexually and asexually.
Sponges are able to reproduce sexually. This form of reproduction is most comparable to plants. A male flower forms sperm (pollen) which then floats through the air and attaches to a female plant or flower and fertilizes the egg.
Sponges are hermadrophidic, which means that they have both male and female reproductive organs, but they rarely fertilize themselves. A sponge produces sperm, which then is taken up with the current of water that is being filtered and is spit out of the osculum of the sponge. This sperm then follows the current of the water until it is filtered into another sponge. When this happens, it attaches to the female reproductive organ of the sponge and fertilizes the sponge.
There are three different forms of asexual reproduction and each of them are very amazing. These three forms of reproduction are Budding, Gemmule Formation and Regeneration. Budding means that a sponge is able to form a set of cells that are on the external portion of the body. This set of cells eventually form into a complete sponge that is independent of the sponges that it is connected to. Then this new creature breaks off of the original sponge and becomes an independent and separate creature.
Gemmule Formation is technically budding, but it is very different than the common budding. A gemmule is a bud that is within the sponge. It has a protective layer around it and is able to survive through very harsh/unfavorable conditions. Even if they are conditions that kill the sponge that the gemmule is within, the gemmule will survive and will be able to form into a complete sponge.
Regeneration is an almost scary form of reproduction. I have seen this form of reproduction on many sci-fi movies, but I never knew that it was a true form of reproduction. If a sponge is broken into many different pieces, it is able to turn into a new sponge. If you take a sponge and separate it into two broken pieces, it is able to become two complete sponges. Not only this, but one single cell from the original sponge is able to form into an entirely new sponge!
3 Sponge Categories
There are three main categories of sponge body structures. These three are Asconoid, Syconoid and Leuconoid. The Asconoid is the common form of sponge this form of sponge has the three layers that were described above and it has only one osculum. Scyonoid’s are similar to the Asconoid sponge, but they are larger and their flagellated collar cells are within the pores (they line the holes that go through the body of the sponge). The Leuconoid sponge is larger than the other two forms and has many chambers within the sponge. Each of these chambers has collar cells lining them. These many chambers then filter out to one osculum.
To look at the Phylum Cnidaria (which includes corals, jellyfish, sea anemones and more) follow this link:
Sea Sponges in Commerce
We may not think of sea sponges as something that we would find in many stores we walk into, but the truth is that sea sponges are quite common. One of the most common uses of the sea sponge is to make natural loofahs or natural sponges.
If this has piqued your interest at all, I have provided a couple of links to different products made of this wonderful phylum.
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In writing this article I referred to these sources:
University of California Museum of Paleontology
Inquiry into Life by Sylvia Mader