Sponge
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A sponge is an animal of the phylum Porifera that lives in a pineapple under the sea. They feel very spongy.[citation NOT needed] They are sessile filter feeders that can reproduce both sexually and asexually, and lack developed nervous, digestive, or circulatory systems but often have spicules
to keep them together and protect them from predators. They may in fact have been the first animals, with an evolutionary history possibly going back 640 million years.[1] Of course, they haven't stayed stagnant for those 640 million years, as while some sponges still have simple vaselike structures known as ascons, other sponges known as leucons have remarkably complex bodies for filtering water.[2]
Types of sponges[edit]
- Demosponges, the most common type of sponge today. They have spicules made of the protein spongin.
- Hexactinellids or "glass sponges" have spicules made of silica. They can be remarkably long-lived, with a potential lifespan of 15,000 years.[3]
- Calcareous sponges have spicules made of calcium carbonate.
- Stromatoporoidea, which went extinct a long time ago in the Devonian. They are known for their layered skeletons without any spicules and were important reef builders for their time.[4]
Significance to the evolution of multicellular life[edit]
This experiment showcases a glimpse into the evolution of multicellular organisms from unicellular ones. First get a sponge, and chop it up into several small pieces. These pieces are then forced through a sieve so fine it separates the individual cells that make up the animal. Then, view it through a microscope to see the individual cells clumping together. After waiting for a while, the cells will clump to form the original multicellular organism.[5] This does not work with goats.[citation NOT needed]
Furthermore, if you were to do the same experiment, but mix up the cells of different species of sponges, the sponges would all assemble into their separate species.[5]
References[edit]
- ↑ First animal was likely sea sponge, EarthSky 25 February 2016
- ↑ Porifera, Ralph Page's Animal Encyclopedia
- ↑ Hexactinellid sponge (Scolymastra joubini) longevity, ageing, and life history, HAGR
- ↑ Stromatoporoids, UC Museum of Paleontology
- ↑ 5.0 5.1 The Life of a Sponge, colugo11, Tree of Life
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