3.1 Principles of marine taxonomy and phylogeny

Marine taxonomy organizes ocean life into groups based on shared traits. From sponges to sharks, this system helps scientists understand relationships between species. It's like creating a family tree for all sea creatures, showing how they're connected through evolution.

Phylogeny takes this further by mapping out evolutionary history. By studying physical features and DNA, researchers can trace how marine life has changed over time. This helps explain why some sea animals look similar but aren't closely related, and others look different but share a common ancestor.

Marine Taxonomy Principles and Methods

Principles of marine taxonomy

Top images from around the web for Principles of marine taxonomy

• 

  The Taxonomic Classification System | Biology for Majors I View original

  Is this image relevant?

• 

  8.3C: The Levels of Classification - Biology LibreTexts View original

  Is this image relevant?

• 

  File:Taxonomic ranking.svg - Wikimedia Commons View original

  Is this image relevant?

• 

  The Taxonomic Classification System | Biology for Majors I View original

  Is this image relevant?

• 

  8.3C: The Levels of Classification - Biology LibreTexts View original

  Is this image relevant?

1 of 3

Top images from around the web for Principles of marine taxonomy

• 

  The Taxonomic Classification System | Biology for Majors I View original

  Is this image relevant?

• 

  8.3C: The Levels of Classification - Biology LibreTexts View original

  Is this image relevant?

• 

  File:Taxonomic ranking.svg - Wikimedia Commons View original

  Is this image relevant?

• 

  The Taxonomic Classification System | Biology for Majors I View original

  Is this image relevant?

• 

  8.3C: The Levels of Classification - Biology LibreTexts View original

  Is this image relevant?

1 of 3

• Taxonomy names, describes and classifies organisms into groups based on shared characteristics
  • Standardizes categorization and naming conventions
  • Enables understanding of evolutionary relationships
• Taxonomic classification organizes life in a hierarchical manner, with each rank being more specific than the one above it
  • Hierarchy: Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species
• Binomial nomenclature names species using a two-part name
  • Genus name capitalized and specific epithet lowercase, both italicized (e.g., Carcharodon carcharias for great white shark)
• Morphological characteristics primarily used for classification
  • Includes external and internal anatomical features
  • Can also include behavior, life history, and ecological traits
• Molecular data increasingly used to refine classifications
  • DNA sequencing helps resolve evolutionary relationships and identify cryptic species

Features of marine phyla

• Porifera (sponges)
  • Multicellular, asymmetrical, sessile animals lacking true tissues and organs
  • Possess pores, channels, and chambers for water flow and filtering
• Cnidaria (jellyfish, corals, anemones)
  • Radially symmetrical with ectoderm and endoderm tissue layers
  • Possess cnidocytes for defense and prey capture
  • Exhibit polyp (sessile) and medusa (free-swimming) body forms
• Mollusca (snails, bivalves, cephalopods)
  • Soft-bodied animals, often with a calcareous shell
  • Possess a muscular foot, mantle, and radula
  • Diverse range of body forms and lifestyles
• Arthropoda (crustaceans, horseshoe crabs, sea spiders)
  • Segmented bodies with jointed appendages and an exoskeleton
  • Undergo molting to grow and develop
  • Highly diverse and abundant in marine environments
• Echinodermata (sea stars, sea urchins, sea cucumbers)
  • Pentaradial symmetry in adults, bilateral symmetry in larvae
  • Endoskeleton composed of calcite plates
  • Possess a water vascular system for locomotion, feeding, and gas exchange

Phylogeny and Evolutionary Relationships

Phylogeny in marine evolution

• Phylogeny studies evolutionary relationships among organisms
  • Depicts the history of lineages as they change over time
  • Represented by branching diagrams called phylogenetic trees
• Phylogenetic trees illustrate common ancestry and divergence of lineages
  • Nodes represent common ancestors, branches represent lineages
  • Closely related organisms share more recent common ancestors
• Understanding phylogeny is crucial for:
  • Tracing the evolution of traits and adaptations
  • Identifying patterns of diversification and extinction
  • Resolving taxonomic classifications based on evolutionary relationships
• Phylogenies are constructed using various types of data:
  • Morphological characters
  • Molecular data (DNA sequences)
  • Fossil evidence
• Comparative analysis of characters across taxa infers evolutionary relationships
  • Shared derived characters (synapomorphies) indicate common ancestry
  • Convergent evolution can lead to similar traits in distantly related taxa

Taxonomic ranks for marine life

• Domain: Highest rank, distinguishing Archaea, Bacteria, and Eukarya
• Kingdom: Second-highest rank, separating organisms based on broad characteristics (Animalia, Plantae, Fungi, Protista)
• Phylum: Major division within a kingdom, based on fundamental body plan and organization (Chordata, Arthropoda, Mollusca, Echinodermata)
• Class: Subdivision of a phylum, based on more specific shared characteristics (Chondrichthyes, Anthozoa)
• Order: Group of related families sharing a common ancestor (Cetacea, Decapoda)
• Family: Group of related genera with similar characteristics (Delphinidae, Penaeidae)
• Genus: Group of closely related species (Stenella, Penaeus)
• Species: Fundamental unit of classification, individuals capable of interbreeding and producing fertile offspring (Stenella longirostris, Penaeus monodon)