Phylum Arthropoda

• General characteristics: bilateral symmetry, segmented body plan, exoskeletal bodies with exoskeleton made of chitin, largest and most successful phylum (70% of all animals), molting allows for a new skeleton to form, prominent cephalization and a ventral nerve cord, open circulatory system
• General characteristics: bilateral symmetry, segmented body plan, exoskeletal bodies with exoskeleton made of chitin, largest and most successful phylum (70% of all animals), molting allows for a new skeleton to form, prominent cephalization and a ventral nerve cord, open circulatory system
• Class Arachnida: scorpions, spiders, ticks and mites
• Class diplopoda: millipedes
• class chilopoda: centipedes
• class insecta: moths, flies, ants, bees, termites, butterflies, etc. (90% of the phylum)
• class crustacea: crayfish, lobsters, crabs, etc.
• all arthopods have a body that uses an exoskeleton for support and structure. within the exoskeleton, their bodies are soft, and are articulated with jointed appendages (origin of the name)
• external limbs maneuver food into the mouth for consumption (mandibles)
• arthropods have a complete digestive system with mouth, esophagus, stomach, intestine, and anus. Within the esophagus are teeth-like surfaces of chitin that grind up food called a gastric mill
• Have an open circulatory system, with organs suspended inside a large central sinus within the body cavity. Gills protected by the exoskeleton oxygenate the blood as the crayfish moves.
• A central heart keeps the blood moving continuously around the organs
• Green gland: located in crayfish head that allows for excretion of wastes. Wastes are collected and excreted as the crayfish swims backwards to avoid predation
• highly developed nervous system, developed brain, and many sensory organs
• Crayfish have compound eyes for high visual acuity as well as sevel pairs of antennae that are touch-sensitive and contain statocysts (for balance). The exoskeleton is also covered in touch-sensitive hairs
• External fertilization produces a group of fertilized eggs that are carried by several rear pairs of appendages until ready to hatch.
• Ecological roles: pollinators, prey, predators, parasites.