Phylum Arthropoda & Echinodermata Flashcards
What organisms phylum Arthropoda
Arthropods; 2/3 of every known species are arthropods
Arthropod body plan
Segmented body, hard exoskeleton, jointed appendages
How are modified appendages structured in arthropods?
They are jointed and come in pairs
Cuticle (arthropod)
Exoskeleton made of layers of protein and chitin covering the entire body (protects and provides points of attachment for muscles), must be shed for growth to occur
-reduces water loss and prevents desiccation, provides structural support also
General Characteristics of Arthropods
Exoskeleton, eyes, olfactory receptors, antennae, open circulatory system
How do arthropods respirate?
-Aquatic species have gills with feathery extensions
-Terrestrial species have internal surfaces specialized for gas exchange (i.e. insect tracheal system)
What are the three major lineages that diverged early in the arthropod evolution?
Chelicerates, myriapods, and pancrustaceans
What organisms are included in Chelicerates?
Sea spiders, horseshoe crabs, scorpions, ticks, mites, and spiders
What organisms are included in myriapods?
Centipedes and millipedes
What organisms are included in pancrustaceans?
Insects, lobsters, shrimp, barnacles, and other crustaceans
Chelicerates
-named for claw like feeding appendages called chelicerae
-most marine chelicerates are extinct; sea spiders and horseshoe crabs only surviving groups
-most modern are arachnids: spiders, scorpions, ticks, and mites
What appendages do arachnids have?
Chelicerae, pedipalps, and four pairs of walking legs.
Arachnid General Characteristics
Book lungs to breathe, many spiders produce silk from abdominal glands
What appendages do myriapods have?
A pair of antennae and three pairs of appendages modified as mouthparts
