General Characteristics of Invertebrates

General Characteristics of Invertebrates

• Single-celled animals, some colonial, live in aquatic or terrestrial environments.
• Most are microscopic.
• Lack organs and tissues, but have specialized organelles.
• Diverse feeding types: free-living, symbiotic, mutualistic, commensalistic, parasitic.
• Movement via pseudopodia, flagella, or cilia.
• Some have simple internal/external structures, others are naked.
• Feeding types include autotrophic, heterotrophic, or saprozoic.
• Reproduction: asexual (fission, budding), sexual (conjugation, syngamy).

Invertebrate Importance

• Biological control agents.
• Food source for some fish (shrimp, shellfish).
• Pollinators (e.g., insects).
• Produce beneficial substances (bees, silkworms).

Harms of Invertebrates

• Disease vectors (malaria parasite, tapeworms, roundworms).
• Damage to ships' surfaces.
• Disease carriers (e.g., mosquitoes).

Protozoa Classification

• Nucleus surrounded by a membrane, connecting internal components and cytoplasm.
• Contains genetic material (DNA) on chromosomes within the nucleus.
• Often includes one or more nucleoli.
• Cytoplasm sometimes divided into ectoplasm and endoplasm.
• Ectoplasm is more solid, contains bases of cilia/flagella.
• Endoplasm is more granular, contains nucleus/organelles.

Protozoa Movement

• Primary means of movement: cilia, flagella, pseudopodia.
• Cilia are made of microtubules (axoneme) covered by a cell membrane.
• Pseudopodia are temporary/semi-permanent extensions of protoplasm, common in amoebas. Four types (lopodia, filopodia, rhizopodia, axopodia) based on structure and shape.

Protozoa Feeding

• Autotrophic or Heterotrophic, based on ability to synthesize organic components from inorganic materials or obtaining it from other organisms.
• Food vacuoles contain food particles and liquid.
• Vacuole shape varies depending on the organism and food size (flagellates/amoebas: food particle shapes; ciliates: spherical shapes.)

Protozoa Nutrition and Respiration

• Autotrophic: photosynthetic organisms that produce their own food using chlorophyll.
• Saprozoic: obtain nutrition through cellular “drinking” (pinocytosis), or direct transfer of dissolved substances (diffusion, facilitated transport, active transport).
• Mixotrophic: can use both autotrophic and saprozoic nutrition methods, depending on the environment.
• Respiration (breathing): Aerobic or anaerobic.

Protozoa Excretion

• Remove water-soluble metabolic waste through diffusion across the cell membrane, or via contractile vacuoles.
• Insoluble waste is expelled via food vacuoles or cytopyge.

Explore the diverse world of invertebrates through this quiz, which covers their unique characteristics, ecological importance, and potential harms. Understand their classifications and the various modes of reproduction they employ. Test your knowledge on the vital roles invertebrates play in ecosystems and their impact on human activities.