ENTM 10 SPRING 2025 — Lecture Topic 2: Origins and Relatives

1. Systematic Framework

• Taxonomy:
  The science of naming, defining, and classifying organisms into groups based on shared characteristics.

• Carolus Linnaeus:
  The “father of taxonomy” developed the system of binomial nomenclature. Binomial nomenclature is the biological system of naming organisms. The name is composed of two terms: the first term indicates the genus, and the second term indicates the species of the organism.”

• Systema Naturae:
  A publication by Linnaeus that laid the foundation for modern taxonomy.

  • System for naming, classifying, and ranking organisms

  • Binomial nomenclature:
    A two-part scientific naming system using Genus and species (e.g., Homo sapiens).

  • Hierarchical system to place organisms in relation to each other:
    Kingdom → Phylum → Class → Order → Family → Genus → Species

  • Explains evolutionary relationships among different groups

• Examples of binomial nomenclature:

  • Apis mellifera (honey bee)

  • Drosophila melanogaster (fruit fly)

  • Cimex lectularius (bed bug)

2. Relationships among Taxa

• Phylogeny:
  Evolutionary history of a species or group.

• Phylogenesis:
  The origin and diversification of a group of organisms through evolution.

• Monophyletic group:
  A group that includes a common ancestor and all its descendants.

• Polyphyletic group:
  A group that does not include the most recent common ancestor of all members.

3. Origin of Phylum Arthropoda

• Theoretical origin of Phylum Arthropoda and Class Insecta:
  Likely arose from a common segmented ancestor related to annelids.

• Phylum Annelida (ringed worms):
  Segmented body, no jointed appendages, closed circulatory system.

• Phylum Onychophora (walking worms):
  Soft-bodied, lobopod legs, tracheal system, considered a transitional group.

4. Phylum Arthropoda

• Subphylum Trilobitomorpha:
  Extinct marine arthropods; three-lobed body, biramous (branched) legs.

5. Subphylum Chelicerata

• Examples:

  • Marine: Horseshoe crabs

  • Terrestrial: Spiders, scorpions, ticks, mites

• Two body regions: Cephalothorax and abdomen

• First appendages: Chelicerae (used for feeding)

• Pedipalp (function?):
  Sensory, reproductive, or prey handling (varies by species)

• Legs:
  Four pairs (8 total)

• Eyes:
  Usually simple eyes (ocelli), sometimes compound

• Book lungs (or book gills):
  Respiratory structures for gas exchange

6. Subphylum Crustacea

• Examples:
  Crabs, lobsters, shrimp, barnacles, isopods

• Habitats:
  Mostly aquatic (marine and freshwater)

• Antennae:
  Two pairs

• Legs:
  Five or more pairs (variable)

• Two body regions: Cephalothorax & abdomen

• Gills:
  Present for aquatic respiration

7. Subphylum Myriapoda

• Examples:
  Millipedes and centipedes

• Antennae:
  One pair

• Legs:
  Many; paired legs per body segment

• Classes in Subphylum Myriapoda:

  • Class Diplopoda (millipedes):
    Two pairs of legs per segment, slow, herbivorous, cylindrical body

  • Class Chilopoda (centipedes):
    One pair of legs per segment, fast, carnivorous, flattened body

8. Subphylum Hexapoda

(meaning? – six legs)

• Class Entognatha — may be polyphyletic

  • Protura

  • Diplura

  • Collembola

• Class Insecta

  • Three major body regions: Head, thorax, abdomen

  • Wings: Usually 2 pairs (can vary or be absent)

  • Eyes: Compound and simple (ocelli)

  • Antennae: One pair

  • Mouthparts: Highly variable; adapted for chewing, sucking, piercing, siphoning, etc.

Benefits to eating bugs:

• High protein content: Insects can provide a rich source of protein, often exceeding that of traditional livestock.

• Low environmental impact: Rearing insects typically requires less land, water, and feed compared to conventional animal agriculture.

• Nutritional diversity: Many edible insects are high in essential vitamins and minerals, contributing to a balanced diet.

• Rapid reproduction: Insects can be harvested quickly and sustainably, making them a viable food source in a growing population.

• High feed-conversion efficiency

• Organic side streams, reducing

environmental impact

• Emits less GHGs and little ammonia

• Requires less water

• Few or no animal welfare issues

• Low risk of transmitting zoonotic

diseases (caused by germs that

spread between animals and people)