Arthropoda Summary

Filo Arthropoda - Characteristics

  • Exoskeleton:
    • Cuticle with protein, lipid, chitin, and sometimes CaCO3CaCO_3.
    • Produced by the epidermis; provides protection without impeding movement.
    • Chitin is insoluble in water, bases, and weak acids.
    • May or may not be soft and permeable.
    • Can be hardened by calcification or sclerotization.
  • No motile cilia.
  • Complex muscular system.
    • Exoskeleton for muscle adhesion.
    • Striated muscles: fast action.
    • Smooth muscles: in visceral organs.
  • Coelom: reduced in adults; coelomic fluid doesn't act as a skeleton.
  • Open circulatory system with dorsal contractile heart, arteries & hemocoel.
  • Excretion:
    • Paired glands, homologous to metanephridia (Coxal, Antennal, Maxillary).
    • Malpighian tubules in insects and spiders.

Classification of Arthropoda

  • Sub-Phyla:
    • Trilobita (extinct)
    • Sub-Philo Chelicerata
    • Myriapoda
    • Crustacea
    • Hexapoda

Clase Merostomata

  • Xiphosura ("Horseshoe Crabs")
    • Blood contains lysado de amebocitos, used to detect endotoxins in medical products.
  • Euryptéridos (extinct) and Xifosuros (4 species)

Clase Arachnida - Orders

  • Araneae
  • Palpigradi
  • Trigonotarbida
  • Ricinuclei (not in PR)
  • Amblypygi
  • Thelyphonida (Uropygida) (not in PR)
  • Acari
  • Opiliones
  • Schizomida
  • Solifugae
  • Pseudoscorpiones
  • Scorpiones

Selected Arachnida Species

  • Araña boba (Heteropoda venatoria)
    • Hides during the day, hunts cockroaches at night.
    • Females carry eggs in a white sac (ovoteca).
  • Araña peluda de Puerto Rico (Cyrtopholis portoricae)
    • Lives in tunnels.
    • Prey for avispa cazadora (Pepsis marginata).
  • Tarántula parda (Caribena laeta)
    • Builds web nests in various locations.
  • Araña cangrejito (Gasteracantha tetracantha)
    • Crab-like shape with spines and mottled coloration.
  • Argiope plateada (Argiope argentata)
    • Silver color with tubercles, builds webs in bushes.
  • Arañas Saltadoras or Saltarinas
    • 25 species in Puerto Rico

Orden Opiliones ("Daddy-Long-Legs")

  • Abdomen segmented.
  • Second pair of legs is longer and for sensory function.
  • Odoriferous glands secrete a strong smell.

Orden Acari

  • Mouthparts on anterior capitulum.
    * Chelicerae: assist in piercing, tearing, or trapping
    * Pedipalps with fused base.
    * Hypostome, rostrum, and tectum extend over mouth.
  • Examples:
    • Demodex folliculorum: human follicle mite.
    • Sarcoptes scabiei: human scabies mite.

Clase Chilopoda

  • Orden Scutigeromorpha
  • Orden Geophilomorpha
    • Elongated, thin bodies with many segments & legs (31-181 pairs).
    • Lack ocelli, antennae with 14 segments.
  • Orden Scolopendromorpha
    • Large centipedes, 21-23 pairs of legs, antennae with 17+ segments.
    • Some have four ocelli on each side of head.
    • Ciempiés gigante (Scolopendra alternans): Largest species, 18cm, brownish-orange.
    • Scolopendridae:
      • Scolopendra: Triangular spiracles.
      • Otostigmus: Oval spiracles, no internal levantones.
      • Rhysida: Oval spiracles, with internal levantones.

Clase Diplopoda

  • Eumillipes ersephone – 1306 legs
  • Anadenobolus arboreus
  • Anadenobolus monilicornis
    • Banded coloration, possibly introduced.