Biology: Characteristics of Protozoa

Characteristics of Protozoa

• Eukaryotic, single-celled microorganisms
• Typically microscopic, ranging from 10-500 μm in size
• Can be found in almost every environment, including freshwater, saltwater, and soil
• Most protozoa are motile, using structures such as cilia, flagella, or pseudopodia to move

Nutrition and Digestion

• Heterotrophic, obtaining energy by consuming other organisms or organic matter
• Some protozoa are predators, capturing and ingesting prey whole
• Others are saprotrophic, breaking down organic matter externally and absorbing the resulting nutrients
• Digestion occurs within food vacuoles, where enzymes break down ingested material

Reproduction and Life Cycles

• Asexual reproduction: binary fission, budding, or fragmentation
• Sexual reproduction: conjugation, involving the exchange of genetic material between two individuals
• Some protozoa have complex life cycles, involving multiple stages and hosts (e.g., Plasmodium, which causes malaria)

Classification and Diversity

• Protozoa are a polyphyletic group, meaning they do not share a common ancestor
• Traditionally divided into four main groups: Sarcodina (amoebas), Mastigophora (flagellates), Ciliophora (ciliates), and Sporozoa (spore-forming protozoa)
• Over 30,000 known species, with many more thought to exist

Ecological Roles

• Decomposers: breaking down organic matter and recycling nutrients
• Predators: regulating populations of bacteria, algae, and other small organisms
• Parasites: causing disease in animals, including humans (e.g., malaria, giardiasis)
• Food sources: serving as a food source for other organisms, such as zooplankton and fish

Characteristics of Protozoa

• Protozoa are eukaryotic, single-celled microorganisms
• They are typically microscopic, ranging from 10-500 μm in size
• Protozoa can be found in almost every environment, including freshwater, saltwater, and soil
• Most protozoa are motile, using structures such as cilia, flagella, or pseudopodia to move

Nutrition and Digestion

• Protozoa are heterotrophic, obtaining energy by consuming other organisms or organic matter
• Some protozoa are predators, capturing and ingesting prey whole
• Others are saprotrophic, breaking down organic matter externally and absorbing the resulting nutrients
• Digestion occurs within food vacuoles, where enzymes break down ingested material

Reproduction and Life Cycles

• Protozoa can reproduce asexually through binary fission, budding, or fragmentation
• Sexual reproduction involves conjugation, where genetic material is exchanged between two individuals
• Some protozoa have complex life cycles, involving multiple stages and hosts (e.g., Plasmodium, which causes malaria)

Classification and Diversity

• Protozoa are a polyphyletic group, meaning they do not share a common ancestor
• They are traditionally divided into four main groups: Sarcodina (amoebas), Mastigophora (flagellates), Ciliophora (ciliates), and Sporozoa (spore-forming protozoa)
• There are over 30,000 known species of protozoa, with many more thought to exist

Ecological Roles

• Protozoa play a crucial role in decomposition, breaking down organic matter and recycling nutrients
• They act as predators, regulating populations of bacteria, algae, and other small organisms
• Some protozoa are parasites, causing disease in animals, including humans (e.g., malaria, giardiasis)
• Protozoa also serve as a food source for other organisms, such as zooplankton and fish