Phylum Arthropoda 1 Arthropoda Overview Subphylum Chelicerata Class Merostomata Class Pycnogonida

Phylum Arthropoda 2 Defining Characteristics – Epidermis produces a segmented, jointed and hardened chitinous exoskeleton with musculature between individual joints of appendages – Complete loss of motile cilia in adult larval stages

Phylum Arthropoda 3 Phylum includes crustaceans, insects, and chelicerates Chelicerates – Primarily terrestrial – Also horseshoe crabs and sea spiders Crustaceans – Marine and freshwater, absent from land

Phylum Arthropoda 4 Arthropod Characters Arthropods have segmented bodies with some or all of the segments bearing jointed appendages Appendages are specialized for :

Phylum Arthropoda 5 The Wonders of Chitin All arthropods have a chitinous jointed exoskeleton How is this detrimental and beneficial?

Phylum Arthropoda 6 Molting (Ecdysis)

Phylum Arthropoda 7 Arthropod Segments Arthropod segments are grouped into body regions Some have two regions – Cephalothorax, and abdomen Some have three regions – Head, thorax, abdomen Many regions have multiple appendages – Appendages are modified for a particular function

Phylum Arthropoda 8 Arthropod Appendages The head usually contains pairs of joint appendages, which are sensory and used in feeding – Antenna’s or feelers are first – Followed by the jaws and mandibles which are used for biting and chewing Mandible and accessory mouth parts aid in handling the food and moving it towards the mouth

Arthropod Appendages

Phylum Arthropoda 10 Arthropod Vision Simple eyes – Light sensitive cells share a common lens Compound eyes – Thousand of closely packed units called ommatidia

Phylum Arthropoda 11 Compound & Simple Eyes

Phylum Arthropoda 12 Digestive system Most arthropods have three main regions: foregut, midgut and hindgut

Phylum Arthropoda 13 Respiration and Circulatory System Extensive surface areas are needed to supply the large oxygen demands of most arthropods – Gills can occur both inside and outside of the of the carapace Circulatory System – Open circulatory system as in molluscs, hearts vary in structure but do exist – Blood is pumped into empty spaces bathing the tissues in blood

Phylum Arthropoda 14 Nervous System and Reproduction