Phylum Arthropoda:
Arthropods include spiders, scorpions, ticks, mites, crustaceans and insects. Live in aquatic and terrestrial
environments. They are herbivorous, carnivorous or omnivorous.
Why have Arthropods achieved such great diversity and abundance?
- They have a versatile exoskeleton
- Segmentation and appendages provide for more efficient locomotion
- Air piped directly to cells
- Highly developed sensory organs
- Complex behaviour patterns
- Use of diverse resources through metamorphosis
Characteristics of Phylum Arthropoda:
Jointed appendages
Live in aquatic and terrestrial habitats
Some can fly
Free-living and parasitic
Bilateral symmetry
Segmented body divided into tagmata
Triploblastic
Reduced coelom, mostly filled with blood (haemocoel)
Cuticular exoskeleton
Complete digestive system
Complex muscular system
Nervous system consists of a dorsal brain and ganglia
Well-developed sensory organs
Sexes usually separate, with paired reproductive organs and ducts
Usually internal fertilisation
Respiration by body surface, gills, trachea or book lungs
Open circulatory system with dorsal contractile heart, arteries and hemocoel
Subphylum Trilobita
Dorsoventrally flattened bottom dwellers and scavengers
Exoskeleton made of chitin, strengthened in some areas with calcium carbonate
3 tagmata: head (cephalon), trunk and pygidium
Cephalon had a pair of antennae, compound eyes, a mouth and 4 pairs of leglike appendages
No true mouthparts
Each body segment except the last bear a pair of biramous appendages
Subphylum Chelicerata:
Includes horseshoe crabs, spiders, ticks, mites, scorpions and sea spiders. Their bodies are composed of 2 tagmata: a
cephalothorax and an abdomen. They have 6 pairs of cephalothoracic appendages that include a pair of chelicerae, a
pair of pedipalps and 4 pairs of walking legs. They have no antennae. Most chelicerates suck liquid food from their
prey.
Class Merostomata:
Subclass Eurypterida:
- Giant water scorpions - 4 pairs of walking legs on their abdomen
- Head has 6 fused segments - 12 segments and a spike like telson
- Compound eyes - Some had anterior appendages modified into
- Chelicerae crushing jaws
- Pedipalps
Arthropods include spiders, scorpions, ticks, mites, crustaceans and insects. Live in aquatic and terrestrial
environments. They are herbivorous, carnivorous or omnivorous.
Why have Arthropods achieved such great diversity and abundance?
- They have a versatile exoskeleton
- Segmentation and appendages provide for more efficient locomotion
- Air piped directly to cells
- Highly developed sensory organs
- Complex behaviour patterns
- Use of diverse resources through metamorphosis
Characteristics of Phylum Arthropoda:
Jointed appendages
Live in aquatic and terrestrial habitats
Some can fly
Free-living and parasitic
Bilateral symmetry
Segmented body divided into tagmata
Triploblastic
Reduced coelom, mostly filled with blood (haemocoel)
Cuticular exoskeleton
Complete digestive system
Complex muscular system
Nervous system consists of a dorsal brain and ganglia
Well-developed sensory organs
Sexes usually separate, with paired reproductive organs and ducts
Usually internal fertilisation
Respiration by body surface, gills, trachea or book lungs
Open circulatory system with dorsal contractile heart, arteries and hemocoel
Subphylum Trilobita
Dorsoventrally flattened bottom dwellers and scavengers
Exoskeleton made of chitin, strengthened in some areas with calcium carbonate
3 tagmata: head (cephalon), trunk and pygidium
Cephalon had a pair of antennae, compound eyes, a mouth and 4 pairs of leglike appendages
No true mouthparts
Each body segment except the last bear a pair of biramous appendages
Subphylum Chelicerata:
Includes horseshoe crabs, spiders, ticks, mites, scorpions and sea spiders. Their bodies are composed of 2 tagmata: a
cephalothorax and an abdomen. They have 6 pairs of cephalothoracic appendages that include a pair of chelicerae, a
pair of pedipalps and 4 pairs of walking legs. They have no antennae. Most chelicerates suck liquid food from their
prey.
Class Merostomata:
Subclass Eurypterida:
- Giant water scorpions - 4 pairs of walking legs on their abdomen
- Head has 6 fused segments - 12 segments and a spike like telson
- Compound eyes - Some had anterior appendages modified into
- Chelicerae crushing jaws
- Pedipalps
