Porifera Flashcards
Name the 7 traits of the phylum Porifera
- Multicellular
- Cells are totipotent - like a stem cell, amoeba can differentiate into a specialized cell and it can also de-differentiate. Capable of recognizing other cells that aren’t theirs
- Asymmetrical
- No “true” tissues - no basement membrane. Basement membrane is a matrix of proteins that support cells and tissues
- Aquiferous systems
- Skeleton of spicules and spongin
- Sessile adults, mostly marine - stays in one place
What are the synapomorphies of Porifera?
Aquiferous systems and the skeleton of spicules and spongin
Porifera major subgroups
Calcarea - has spicules are made of CaCO3. Often found in warm, shallow env. Tube-looking thing
Hexactinellida - has six-rayed spicules and is composed of silicon dioxide. Found in the deepest, coolest part of the ocean
Demospongiae - never has 6-rayed spicules, but their spicules are made of silicon dioxide Mainly spongin
1/3 Body forms of Porifera
Asconoid:
Simplest body plan and sponges are usually tiny. Only consists of the calcarea type
Has porocytes, pinacocyte, mesohyl, ostium, osculum, spongocoel (atrium), and a choanoderm, which holds a layer of choanocytes
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2/3 Body forms of Porifera
Syconoid:
Consists of the calcarea and hexactinellida type
No porocytes because these animals are too complex
Has dermal pore, choanocyte chambers, spongocoel, osculum, mesohyl, and incurrent canals (innovation)
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3/3 Body forms of Porifera
Leuconoid:
All 3 groups (Calcarea, Hexactinellida, Demospongiae) have representatives of the leuconoid.
No porocytes
Has incurrent and excurrent canals (innovation), mesohyl, choanocyte chambers, dermal pores, sponeocoel, endo and exopinacocytes (types of pinaocytes), and osculum
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How do sponges compensate for the growth of volume as it grows in complexity?
The larger the sponges get, the significantly larger the volume gets. The sponges builds a larger surface area to compensate for all the cells that need nutrients
To put it in perspective: x^3 = volume; x^2 = area
The more complex they are, the more holes, canals, and chambers they need to extract nutrients and exchange gases
Water currents and the angle of supply
The morphology of sponges depends on their environment
View notes for visualization
3 types of dermal epithelial cells
- Exopinacocytes - cells that form the external epithelium lining of a sponge
- Gland cells - secretes mucus. Traps and prevents viruses and bacteria inside the sponge. It’s an additional layer of protection
- Porocytes - ONLY IN ASCONOIDS. They’re tubular cells that make up pores to let water in
Mesohyl
A type of mesenchyme. Holds cells, spicules and the mesoglea, which is the gel that holds everything
2 types of cells in the mesohyl
- Gametes
- Amoebocytes
Myocytes
Contractile cells. Open/closes pores
Chromocytes
Gives sponge their colour
Sclerocytes
Cells that build spicules
Spongocytes
Builds spongin; rubbery elements
Rhabdiferous cells
Build mesoglea
Collencytes and lophocytes
Forms collagen. Holds spicules and creates structural integrity of the sponge
Archaeocytes
They’re generalized amoeba cells. Think of them as stem cells and can differentiate
Mainly forms eggs via meiosis
Distributes nutrients across the sponge
Repairs damaged parts of the sponge
7 amoebocytes
Myocytes, chromocytes, sclerocytes, spongocytes, rhabdiferous cells, collencytes and lophocytes, and archeocytes
NOTE: every cell type can revert back to archaeocytes
2 cells that consists of the sponge’s internal lining
- Endopinacocytes - a type of cell that forms the internal lining of the canals of a sponge
- Choanocytes - creates currents in the aquiferous system
Internal transport consists of:
Gas exchange
Excretion
Osmoregulation - ridding the body of excess water. Fresh water cells push extra water out
All of the above requires diffusion of individual cells
Feeding of a sponge (5)
- Bacteria gets stuck in the microvilli of the collar
- Pseudopod reaches for the bacteria and engulfs it via phagocytosis
- Bacteria is brought into the cell body via phagocytosis and vacuole is formed
- Vacuole moves and dumps the bacteria
- An archaeocyte will eat the food via their pseudopods and phagocytosis. It can also donate the rest of the food to different regions of the sponge to make sure all cells are fed
5 functions of choanocytes
- Generate H2O currents
- Feeding
- Gas exchange
- Become sperm - choanocytes can become spermatocytes. Male gametes come from the choanocytes while female gametes come from archaeocytes
- Fertilization process
Indirect life cycle
Low cost/zygote
Low survival
Wide distribution (dispersal)
Low parental care
Direct life cycle
High cost/zygote
High survival
Narrow distribution
High parental care
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Mixed life cycle
Has both qualities of indirect and direct life cycle. Internal fertilization is present
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Modified mix life cycle
A modified version of the mixed life cycle. Unlike mixed life cycle, free spawn occurs first, then internal fertilization
How? The choanocytes bring in the sperm then the sponges release the sperm
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Planktotrophic larval type
“Plankto” meaning that plankton is the main sourve of food. No competition of space between the mom and larvae
Lecithotrophic larval type
“Lecitho” meaning it feeds off yolk. Mom provides food during the larval stage
Types reproduction of sponges
Asexual - fragmentation and budding. Both result in genetically identical spawns
Reduction bodies - reduction body can fall and germinate to form new sponge from the gemmule if the sponge is eaten. The new sponge is genetically identical to mom (asexual)
Sexual - most hermaphroditic. Sponges can be male or female. Some sponges can be protandric, meaning they have male sexual organs while young and female organs later in life. Self-fertilization can occur. Modified mixed development can occur too
Smoking sponges
Sponges don’t have gonads, so choanocytes function to release sperm in concentrated masses making it look like it’s smoking
If the sperm is the same species as the sponge with the egg, it can reproduce with it. Choanocytes will collect the sperm
