Questions and Answers
Into what kingdom did early biologists classify sponges?
Plant kingdom
Sponges belong to what kingdom and what phylum?
Kingdom: Animalia; Phylum: Porifera
Porifera are: unicellular or multicellular?
Porifera are: prokaryotic or eukaryotic?
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What are protozoans?
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What type of symmetry do sponges exhibit?
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What does it mean to be sessile?
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How do sponges obtain their food?
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Where does water enter the sponge through?
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Where does water leave the sponge through?
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What is the function of the amoebocyte?
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Because of the presence of amoebocytes, scientists believe that sponges evolved from protists.
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What two substances give a sponge support?
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What are tiny sponges growing from the main body of the poriferan called?
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What is a gemmule?
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What is a hermaphrodite?
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Porifera are filter feeders.
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What does the primitive structure of a sponge look like?
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What is the ectoderm?
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What is the endoderm?
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What are the pinacocytes?
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What is the spongocoel?
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What are choanocytes?
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What is the porocyte?
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What is the osculum?
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What is the mesenchyme?
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What are the amoebocytes?
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What is spongin?
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What are the spicules?
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Most porifera have a combination of spicules and spongin.
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What are the three ways for sponges to reproduce asexually?
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When does sexual reproduction occur in sponges?
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Should protozoans be considered animals?
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What is meant by 'specialized' cells?
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How is molecular and genetic research influencing our classification of animals?
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Example of mutualism?
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Example of commensalism?
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How long ago did the first animal appear on Earth?
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Study Notes
Classification of Sponges
- Early biologists mistakenly classified sponges in the Plant kingdom due to their plant-like appearance.
- Sponges belong to the Animal kingdom (Kingdom: Animalia) and the Phylum Porifera.
Cellular Characteristics
- Porifera are multicellular and eukaryotic, meaning they have complex cells with a nucleus.
- Protozoans, single-celled eukaryotes, are believed to be evolutionary predecessors of porifera.
Structural Features
- Sponges exhibit asymmetrical body symmetry, lacking a defined shape.
- They are sessile, meaning they are fixed to a substrate and do not move.
Feeding Mechanism
- Sponges obtain food through filter feeding by straining large volumes of water for nutrients.
Water Flow System
- Water enters a sponge through structures called porocytes.
- Water exits through an opening known as the osculum.
Cellular Functions
- Amoebocytes transport food and oxygen within the sponge, performing various functions throughout the organism.
- Pinacocytes form the outermost layer, providing protection and structure.
- Choanocytes line the interior, using flagella to create water currents for feeding.
Support Structures
- Sponges gain structural support from spicules (small, hard particles) and spongin (protein fibers).
- Different ratios of spicules to spongin influence the sponge’s texture.
Reproduction
- Asexual reproduction occurs through budding, gemmules (internal buds), or regeneration of lost parts.
- In sexual reproduction, sponges release sperm into the water for internal fertilization with other sponges' eggs.
Development and Tissue
- Sponges are diploblastic, consisting of two germ layers—ectoderm (outer layer) and endoderm (inner layer).
- Mesenchyme serves as the first connective tissue appearing in sponge embryos, supporting cellular structures.
Evolutionary Insights
- Molecular and genetic research enhances understanding of evolutionary relationships, helping classify animals more accurately.
- Protozoans, with their movement and feeding habits, are considered ancestral forms of animals.
Ecological Relationships
- Mutualism is illustrated when crabs use sponge pieces for shelter, benefiting both species.
- Commensalism occurs as sponges provide habitat for small marine animals, offering shelter without harming the sponge.
Historical Context
- The earliest animal forms appeared approximately 3.5 billion years ago, marking significant evolutionary milestones.
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Description
Test your knowledge on sponges with this quiz! Explore the classification of sponges, their kingdom, and phylum. Learn about their characteristics and importance within the animal kingdom.
