Questions and Answers
What does Phylum Porifera refer to?
What kind of lineage do sponges represent within the Animal Kingdom?
Basal lineage
What does the term 'Porifera' mean?
Pore bearers
What does the term 'Metazoa' refer to?
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Why are sponges considered animals?
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Where do the earliest fossils of sponges date back to?
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Which of the following are general characteristics of sponges?
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What type of symmetry do sponges mostly have?
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What type of cellular organization do sponges have?
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Cells removed from sponges cannot reorganize to regenerate the sponge organism.
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Regeneration is possible in more complex animals that have tissues.
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Do adult sponges have locomotion?
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Sponges have specialized nervous structures.
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How do sponges handle circulation and transport?
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Sponges use specialized structures for osmoregulation.
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Respiration in sponges occurs through active transport.
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What feeding method do sponges utilize?
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What are choanocyte cells responsible for?
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What is the central cavity of a sponge called?
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What is unidirectional water flow in sponges?
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How much water can a 10 cm tall sponge filter in a day?
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What ecological benefit do sponges provide?
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What is mesohyl?
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What are amoebocytes?
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What are spongin fibers?
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What are stiff spicules?
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Study Notes
Phylum Porifera
- Comprises sponges, known as pore bearers, with around 10,000 living species primarily found in marine environments.
- Represents the basal lineage within the Animal Kingdom, indicating its primitive characteristics.
Characteristics of Sponges
- Exhibits only a cellular level of organization; sponges lack true tissues and organs.
- Characterized as multicellular, heterotrophic, with a diplontic life cycle, and possess "Hox-like" homeobox genes.
Evolutionary History
- Fossil evidence dates back to approximately 580 million years ago, although sponges were not classified as animals until the late 19th century.
General Features
- Display asymmetry and lack specialized structures in locomotion, sensory perception, circulatory functions, osmoregulation, respiration, and excretion.
- Possess basic features such as feeding through suspension/filtering and sexual reproduction.
Cellular Organization
- Simplest metazoans, with specialized cell types functioning as part of a single organism; cannot survive independently like unicellular organisms.
- Cells can reaggregate and regenerate, showcasing notable regenerative capabilities absent in more complex animals.
Water Flow and Feeding
- Adults remain stationary (sessile) and utilize a unidirectional water flow for nutrient intake.
- Choanocytes, with their flagellated bodies, create water currents to filter food particles from the water.
Anatomical Components
- The outer sponge wall is lined with epidermal cells.
- Spongocoel serves as the central cavity through which water circulates.
- Osculum functions as the exit point for water, facilitating the expulsion of filtered water.
Unique Roles in Ecosystems
- A 10 cm tall sponge can filter approximately 100 liters of water per day, contributing to the ecological balance.
- Sponges play a critical role in marine environments as efficient filters, positively impacting reef ecosystems.
Mesohyl and Cellular Functions
- Mesohyl is a gelatinous acellular matrix supporting cells like amoebocytes and skeletal components, such as spicules and fibers.
- Amoebocytes are totipotent cells capable of transforming into various cell types crucial for structural support.
Supporting Structures
- Spongin fibers serve as a flexible skeletal element in some sponge species.
- Stiff spicules provide structural integrity; composed of silica or calcium carbonate, these spicules aid in supporting the sponge's architecture.
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Description
Test your knowledge on Phylum Porifera, commonly known as sponges. This quiz covers their characteristics, evolutionary history, and general features. Discover the fascinating aspects of these primitive organisms that represent the basal lineage in the Animal Kingdom.
