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Sponges are in the phylum porifera, which means "pore-bearers" |
Body Plan & Motility
Sponges don't have any sort of mouth, stomach, tissues or organ systems. Instead specialized cells carry out the physiological processes. They are sessile, meaning they are immobile.
- Asymmetrical - no particular pattern
- Body of sponge forms a wall around a large central cavity
- Water enters the sponge through it's pores and is continually circulates through the central cavity
- Choanocytes, also known as collar cells, are specialized cells that use flagella to move water through the sponge
- Water leaves the body though the osculum - a large hole at the top of the sponge
- Spicules, made by specialized cells called amebocytes (aka archaeocytes), interlock to form the skeleton of the sponge
- Epidermal cells form the outermost layer of the sponge
Nutrition
- Sponges are filter feeders, meaning they sift microscopic food particles from the water
- As water moves through the sponge food particles are trapped and engulfed by the choanocytes lining the body cavity
- Particles are then either digested or passed on to the archaeocytes
- The archaeocytes complete the digestive process and transport food throughout the sponge
Reproduction
Sponges can reproduce either sexually or asexually
Sexual Reproduction:
Sexual Reproduction:
- The sponge releases it's sperm into the water where it is carried into another sponge through it's pores
- The archaeocytes carry the sperm to an egg where it is fertilized internally
- After fertilization, the zygote develops into a larva - larva are motile and carried by water currents
- Can bud or form gemmules
Ecological role
- Provide shelter for other organisms such as snails, sea stars, and shrimp
- Symbiotic relationship with other organisms such as algae, bacteria and plantlike protists
- Play an important role in "cleaning up" the ocean floor - amebocytes release chemicals that help break down shells and corals
Adaptations & evolutionary advancement
- Sponges are so different from other organisms, some scientists believe that they evolved independently from other organisms
- There is other evidence that suggests sponges do share a common ancestor with other organisms but separated from this ancestor a very long time before the other organisms did
- One of the sponges adaptations is it's ability to sift food from the water as it moves past the sponge which allows it to sit in a relatively barren area without harm