Questions and Answers
Porifera are also known as?
Do sponges have true embryonic tissues?
False
What does it mean for a sponge to have cells that are totipotent?
The cells change form and function and are mobile throughout the body
Are sponges found in marine waters or freshwaters?
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What is a group of sponges known as?
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What are the three classes of sponges?
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What are the spicules of CALCAREA composed of?
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Do CALCAREA sponges typically live in marine water or freshwater?
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CALCAREA are considered the least primitive of the three classes of sponges.
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What is one defining characteristic of CALCAREA that helps you identify them?
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Would I be correct in assuming a sponge I found is probably of the class Demospongiae?
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What are the spicules of DEMOSPONGIAE made of?
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DEMOSPONGIAE are found exclusively in marine waters at shallow depths.
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Sponges of the class HEXACTINELLIDA are also known as what?
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What are the spicules of HEXACTINELLIDA made of?
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What is unique about the spicules of the HEXACTINELLIDA?
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HEXACTINELLIDA are typically found in shallow depths of freshwater.
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What does it mean for a sponge to be an aquiferous system?
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What structures does a sponge have that provides each cell with the appropriate nutrients and gas exchange?
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What is the body structure of sponges if the sponge does not have true tissues?
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What is mesohyl? Is it cellular? What is found in the mesohyl?
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What type of cells make up the PINACODERM?
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What is the PINACODERM?
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What are PINACOCYTES?
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What defines a pore as a DERMAL PORE?
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What defines a pore as an OSTIA?
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What are these OSTIA cells called?
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What type of cells is the CHOANODERM made up of?
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What is the function of the CHOANODERM?
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What does a CHOANOCYTE look like?
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How does the COLLAR of the CHOANOCYTE aid in obtaining food?
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What are the three general body types for the CALCEROUS and DEMOSPONGES?
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What does the ASCONOID body type look like?
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What do the PINACODERM and CHOANODERM look like in ASCONOIDs?
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Where does the POROCYTE in the ASCONOID lead to?
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What class of sponges can the ASCONOID body type be found?
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What is the osculum in the ASCONOID?
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Identify the path that water flows in the ASCONOID body type.
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What does a SYNCONOID body plan look like?
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Is the MESOHYL thickened or reduced in SYNCONOIDS?
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Is the incurrent opening a dermal pore or an ostia?
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What is the opening into the flagellated chamber called in SYNCONOIDS?
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What is the opening to the SPONGOCOEL called?
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What sponges can you find the body type of a SYNCONOID in?
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Identify the path of water flow in SYNCONOIDS.
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What distinguishes the LEUCONOID from the SYNCONOID and the ASCONOID?
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What does the SPONGOCOEL look like in LEUCONOIDS?
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How does flagellated chambers in the LEUCONOID benefit the organism?
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What class of sponges might you find with LEUCONOID body plans?
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Identify the path of water flow in the LEUCONOID body plan.
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HEXACTINELLIDS do not have a PINACODERM. What do they have instead?
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What does the inside of the HEXACTINELLIDS look like?
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How are flagellated chambers supported in the HEXACTINELLIDS?
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What structure brings water from the lacunae to the chambers?
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Choanocyte chambers and the trabecular network are SYNCITIAL. What does this mean?
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Identify the path of water flow in HEXACTINELLIDS.
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How do sponges support themselves?
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What types of cells secrete COLLAGEN?
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What distinguishes a LOPHOCYTE?
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What distinguishes a COLLENCYTE?
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What distinguishes a SPONGOCYTE?
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Which class is TRUE SPONGIN found in?
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What are the two different compounds that SPICULES can be made of?
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Where are SPICULES found?
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What cells produce the SPICULES?
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What use are SPICULES for us as biologists?
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What are the two general types of SPICULES?
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Which type of SPICULES are found in CALCAREOUS sponges?
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What type of SPICULES are found in DEMOSPONGES and HEXACTINELLIDS?
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How do sponges feed intracellularly?
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Which cells capture small particles for sponges?
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Where does digestion occur?
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What is another method of collecting food particles for sponges?
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What happens to food particles captured by CHOANOCYTES?
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What are three methods of asexual reproduction of sponges?
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What are GEMMULES and what type of sponges use this method of asexual reproduction?
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Most sponges are sequential hermaphrodites, but some are GONOCHORISTIC.
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What cells produce the eggs and sperm?
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What structure are sperm produced in?
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Where are eggs kept?
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Where does fertilization occur?
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A few sponges release sperm but retain eggs. What cells take up the sperm?
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After fertilization, the zygote may spend time in the maternal sponge.
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What type of cleavage does the embryo experience?
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What are the 3 larval types of sponges?
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Sponge larvae are motile (they swim and creep), and are also LECITHOTROPHIC. What does this mean?
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Demosponges typically do not incubate embryos.
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What is odd about CALCAREA larvae and how they develop?
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Study Notes
Porifera (Sponges) Overview
- Porifera is the scientific classification for sponges, known as the simplest multicellular organisms.
- Sponges are characterized as parazoans and lack true embryonic tissues.
Cellular Characteristics
- Sponge cells are totipotent, meaning they can change form and function, and are mobile.
- They absorb water through a unique aquiferous system that facilitates gas exchange and nutrient uptake.
Habitats and Classifications
- Sponges are found in both marine and freshwater environments.
- They are grouped into three main classes:
- Calcarea (calcium carbonate spicules)
- Demospongiae (siliceous spicules)
- Hexactinellida (glass sponges with six-rayed spicules)
Spicule Composition
- Calcarea spicules are made of calcium carbonate, while Demospongiae spicules are siliceous and may include collagen structures.
- Hexactinellida spicules are also siliceous and distinctive due to their six-ray structure.
Body Types
- Sponges exhibit three general body types:
- Asconoid: simple and small vase-like shape.
- Syconoid: more complex, with infoldings creating flagellated chambers.
- Leuconoid: highly folded, resulting in discrete flagellated chambers for efficient nutrient exchange.
Anatomical Structures
- Pinacoderm is the outer layer composed of pinacocytes that provide structure and regulate water flow.
- Choanoderm consists of choanocytes, which generate water currents and capture food through phagocytosis.
- Mesohyl is a noncellular matrix that contains spicules and various cells for support and digestion.
Water Flow Pathways
- Water enters through ostia and dermal pores, leading to the spongocoel and then out through the osculum.
- Each body type has a specific water flow path, adapted for efficient feeding and gas exchange.
Reproductive Strategies
- Sponges can reproduce asexually through fragmentation, budding, or gemmules (dormant clusters in unfavorable conditions).
- Most sponges are sequential hermaphrodites, possessing both male and female reproductive structures.
- Sperm production occurs in spermatic cysts, while eggs are retained in the mesohyl.
Development and Larval Stages
- Fertilization often occurs externally in the water, with the potential for some sponges to retain embryos.
- Embryos undergo holoblastic cleavage into a coeloblastula, which features three types of larvae: coeloblastula, parenchymula, and amphiblastula.
- Sponge larvae are motile and lecitotropic, meaning they depend on yolk for nourishment.
Key Identifying Features
- Spicules are crucial for sponge identification, comprising either megascleres (in calcareous sponges) or both megascleres and microscleres (in demosponges and hexactinellids).
- Each cell type within sponges has specialized roles, from maintaining structural integrity to facilitating nutrition and reproduction.
By understanding these facets of Porifera, one can appreciate their biological significance and adaptability within various ecosystems.
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Description
Test your knowledge about Porifera, commonly known as sponges, with these flashcards. This quiz covers essential characteristics, anatomical features, and habitats of sponges, including their cellular structure and totipotent abilities. Suitable for biology students and enthusiasts alike!