Hydra are fascinating, small animals measuring only a few millimeters in length.
They inhabit freshwater environments.
Capable of attacking and consuming tiny prey; reproduce asexually through budding, creating genetically identical offspring.
While they appear plant-like to the untrained eye, they are classified as animals.
Taxonomy: The science of naming and classifying species.
Formal classification initiated by Carl Linnaeus in the 18th century.
Lack of knowledge about protists and bacteria at that time; limited understanding of cell structure and genetic relationships.
As scientific understanding evolves (like understanding DNA), the classification of organisms may change.
Mnemonic for remembering classification: "Dear King Paramecium Cares Only For Green Spirulina" (reflects personal bias toward protists).
Three Domains:
Bacteria
Composed of prokaryotic organisms.
Includes beneficial bacteria (intestinal health), harmful bacteria, and environmental bacteria that aid in processes like nitrogen fixation.
Archaea
Prokaryotes with distinct DNA and structural differences from bacteria.
Often extremophiles, thrive in extreme environments like high salt (e.g., Dead Sea) and low oxygen (e.g., methanogens producing methane).
Include thermophiles that thrive in high-temperature environments.
Eukarya
Comprised of eukaryotic organisms with complex cells.
Changing Nature of Kingdoms:
No universal agreement among scientists on kingdom organization; classifications vary between 5 and 6 kingdom systems.
Highlights the fluid nature of taxonomic categories as scientific understanding advances.
Protista: Highly diverse; may be categorized further in the future.
Includes animal-like, plant-like, and fungi-like protists.
Autotrophic (self-feeding) and heterotrophic (dependent on others for energy) types.
Mostly unicellular; some are multicellular; cell walls (if present) may be made of cellulose.
Fungi: Heterotrophic, typically multicellular (but can be unicellular) organisms with chitin in their cell walls.
Example: athlete's foot fungus, which feeds on dead skin cells.
Plantae: Multicellular autotrophs (including carnivorous plants) that generate glucose from sunlight; possess cellulose cell walls.
Animalia: Heterotrophic and mostly multicellular kingdom, includes hydra.
Classification becomes more specific as we descend from Domain to Species:
Phylum
Class
Order
Family
Genus
Species: Most specific level in classification.
Initiated by Carl Linnaeus: two-part naming system using Latin/Greek roots.
Example of species name: Genus species.
Genus: First name (capitalized, italicized).
Specific epithet: Second name (lowercase, italicized).
Importance of scientific names:
Mitigates confusion caused by common names, which can vary by region (e.g., mountain lion = puma, cougar, Texas panther).
Provides a standardized way to identify species globally.
Emphasis on the importance of curiosity and understanding the classification system in biology, as exemplified by hydra studies.