Lab Lecture Sponges

Overview of Animal Kingdom Structure

  • Introduction to the classification of animals.

  • Discussion of Kingdom and Phylum and subsequent classifications of smaller subgroups.

Class Calcarea

  • Definition: Class Calcarea consists of calcareous sponges, which are primarily composed of calcium carbonate.

Key Characteristics

  • Calcareous sponges are made of calcium carbonate.

  • Definition of Genus: A term used in the biological classification of organisms.

    • Example Genus: Leukosynia.

    • Visual representation in slides where the specimen appears flattened when placed on a slide.

  • Structures of interest include:

    • Whole specimen: This indicates a full representation, although they tend to flatten when observed under a microscope.

    • Visualization: Specimens are described as being linear but appear squished when viewed on slides.

Functional Anatomy of Sponges

  • Description of sponges as filter feeders without a true mouth; they draw in water to extract food particles.

  • Cellular Composition: Sponges consist of a simple structure made up of various types of cells.

Key Structures

  • Dermal Ostia:

    • Definition: Openings in the skin (dermal layer) of the sponge.

    • Function: Allows water to enter the sponge.

  • Spongocoel:

    • Definition: The central cavity within the sponge.

    • Function: Contains water after it flows through the dermal ostia.

  • Choanocytes:

    • Definition: Specialized cells within the sponge that have flagella.

    • Function: Create a water vortex to capture food particles.

    • Similarity to Choanoflagellates in structure.

    • Food intake mechanism: Water enters via dermal ostia → into spongocoel → captures food as water moves past choanocytes.

  • Flow of Water:

    • Pathway: Water enters through the dermal ostia → spongocoel → exits through ostium.

  • Body Plan:

    • Basic structure includes spikes made of calcium carbonate (calcareous spicules) and jelly-like substance (mesohyl).

Cell Types in Sponges

  • Choanocytes:

    • Function: Responsible for feeding by trapping food particles from water.

  • Pinacocytes:

    • Function: Form the outer layer of the sponge (skin).

  • Porocytes:

    • Function: Cells that line the dermal ostia, regulating water flow.

Class Sycon

  • A more complex type of sponge compared to class Calcarea.

  • Examples of Genus: Grantia, Scypha, Rhabdocalyptus. All share similar characteristics and classification.

Characteristics

  • Canal System: Much more complex than class Calcarea.

  • Water Flow Mechanism: Similar to the Calcarea but with adaptations to slow down water movement for better food capture.

    • Structure: Mini-maze like formation inside the sponge to facilitate slow movement of water.

Canal System Details

  1. Dermal Ostia: Openings through which water enters.

  2. Incurrent Canal: The canal that leads from dermal ostia into the sponge body.

  3. Prosopyle: Transition canal from the incurrent canal.

  4. Radial Canal: Lined with choanocytes for food capture.

  5. Apopyle: Opening that leads water out of the radial canal.

  6. Excurrent Canal: Pathway leading out of the sponge.

  7. Spongocoel: Central cavity.

  • Visualization: Cross-section diagrams help illustrate flow pathways.

Class Demospongiae

  • Overview: Sponges in this class are primarily made of spongin (a protein).

  • Example Genus: Spongilla.

Spicules

  • Definition: Sharp structures that provide support and structure to the sponge.

  • Gemmules:

    • Definition: Asexual reproductive structure represented as circular formations among spicules.

    • Importance: Used for reproduction.

Structural Complexity of Sponges

  • Comparison between simpler structures of Calcarea and more complex systems in Demospongiae and Sycon.

  • The Demospongiae exhibit more extensive canal systems improving water flow through the sponge.

  • Pinacocytes continue to serve in the outer skin layer, while the choanocytes function in the internal feeding processes.

Class Hexactinellida

  • Definition: Consists of glass sponges, composed of silica, giving them a glass-like structure.

  • Caution: These sponges are fragile; mishandling can lead to breakage.

Bath Sponges

  • Use: Traditional bath sponges, commonly used for personal care. Also a part of the class Demospongiae.

  • Material: Historical uses were made from the natural sponge material for bathing purposes.

Summary of Sponge Classification

  • Kingdom and Phylum need to be emphasized.

  • The common classifications include:

    • Class Calcarea: Calcareous sponges (Calcium Carbonate). Genus: Leukosynia.

    • Class Sycon: More complex sponge structures.

    • Class Demospongiae: Made from spongin, with intricate canal systems and structures such as gemmules.

    • Class Hexactinellida: Glass sponges made of silica.

  • Materials Info: Knowledge about various materials representing different classifications is crucial for understanding sponge biology and ecology.

  • Practical Observations: Care must be taken when handling spongy materials to avoid damage, particularly those classified as Hexactinellida and bath sponges.