Skip to main content
Pearson+ LogoPearson+ Logo

Porifera and Cnideria definitions Flashcards

Porifera and Cnideria definitions
1/15
  • Porifera
    Sessile, hermaphroditic filter feeders with a porous body, central cavity (spongocoel), and flagellated cells (choanocytes) for intracellular digestion; supported by a gelatinous matrix (mesohyl).
  • Sponges
    Aquatic, sessile animals with porous bodies that filter feed by drawing water through specialized cells called choanocytes; capable of both sexual and asexual reproduction.
  • Choanocytes
    Flagellated cells in sponges that capture and digest food particles via phagocytosis, aiding in filter feeding by creating water currents.
  • Phagocytosis
    The process by which a cell engulfs particles or microorganisms, enclosing them in a vesicle for intracellular digestion.
  • Mesohyl
    A gelatinous matrix within sponges that separates cell layers, provides structural support, and aids in nutrient transport through amoebocytes.
  • Amoebocytes
    Cells in sponges that produce structural fibers, transport nutrients, and play a role in digestion and reproduction within the gelatinous matrix called the mesohyl.
  • Cnidarians
    Radially symmetrical animals with a gastrovascular cavity, two body forms (polyp and medusa), and specialized stinging cells (cnidocytes) for capturing prey. Examples include jellyfish and corals.
  • Radial Body Plan
    A body symmetry where an organism can be divided into similar halves by multiple planes passing through the central axis, typical in cnidarians like jellyfish.
  • Gastrovascular Cavity
    A multifunctional cavity in simple animals for digestion and nutrient distribution, serving as both a stomach and circulatory system.
  • Polyp
    A cylindrical body form with a mouth and tentacles facing upward, often attached to a substrate, used for feeding and sometimes capable of limited movement.
  • Medusa
    A free-swimming, umbrella-shaped life stage of cnidarians, with tentacles hanging down and a central mouth on the underside, typically seen in jellyfish.
  • Cnidocytes
    Specialized cells in cnidarians containing nematocysts, which are organelles that discharge barbed threads to capture prey and provide defense.
  • Nematocyst
    A specialized organelle in cnidocytes that ejects a barbed, venomous thread to capture and immobilize prey.
  • Hydrostatic Skeleton
    A fluid-filled cavity surrounded by muscles, where fluid pressure provides structural support and enables movement, functioning similarly to a skeleton in soft-bodied organisms.
  • Anthozoa
    Marine cnidarians like corals and sea anemones, often with calcium carbonate exoskeletons, forming reefs and lacking a medusa stage in their life cycle.