Phylum Arthropoda

Arthropods  Make up about 80% of the known animal species  Insects are by far the most common species of arthropods  Arthropod means joint-footed  Range from the deep sea to mountain peaks  Bilateral symmetry  Growth requires molting

General Arthropod Characteristics Arthropods have: 1. Exoskeleton  - Most prominent characteristic is their outside skeleton, or exoskeleton.  - Exoskeleton provides support, protection and attachment site for muscles. Made of protein and chitin  Chitin is a strong, flexible, polysaccharide  - All arthropods molt, or shed their exoskeletons periodically. After it molts, it grows before the new skeleton hardens.  - Skin glands digest the inner part of the exoskeleton and other glands secrete the new one.

General Arthropod Characteristics Arthropods have: 2. Segmented Bodies  - Have segmented bodies that show various patterns of segment fusion (tagmosis) to form integrated unit like the head, abdomen,...

General Arthropod Characteristics Arthropods have: 3. Jointed Appendages  - Have joints between body sections (includes legs and antennae)  - Have jointed appendages (a structure such as a leg that grows out from the main part of the body)

Arthropod Characteristics  Cephalization is more prominent than in annelids (brain and complex sense organs in the head region)  Special organs sense touch, vibration, and chemicals. The eyes of many arthropods are particularly specialized.  Open circulatory system. The dorsal heart pumps blood from the posterior end of the animal to the anterior end.  - Blood moves through the hemocoel (major body cavity)

Phylum Arthropoda – 2 Subphylum  Subphylum Chelicerates  Class Arachnida  Spiders, scorpions, mites, ticks  Subphylum Mandibulates (4 major classes)  Class Crustacea  Crayfish, Crab, Lobster  Class Chilopoda  Centipedes  Class Diplopoda  Millipedes  Class Insecta  Insects, Grasshoppers

Subphyla Chelicera  Chelicera are pointed appendages (modest pinchers) used for feeding and manipulating food (in lieu of chewing mandibles)  The body of chelicerates has two major parts:  1. The cephalothorax is a fused section composed of the head and any body segments that have legs attached.  2. The abdomen consists of posterior segments that contain most of the internal organs.  Lack antennae  Nearly all have 4 legs lmuPdek

Subphlya Chelicera: Class Arachnida

Subphyla Mandibulata  Unlike chelicerates, mandibulates have - mandibles, or jaws, for chewing food.  All mandibulates have antennae  - segmented sense organs on the head  Three distinct body regions  - head, thorax, abdomen  They have three or more pairs of walking legs

Subphyla Mandibulata: 1. Class Crustacea  Crustaceans typically have:  - two pairs of antennae  - two or three body sections  Cephalothorax – head fused with the thorax  - chewing mouthparts called mandibles. -5 or more pairs of legs Primarily aquatic, few terrestrial

Ex: Crustacean

Subphyla Mandibulata: 2. Class Chilopoda (centipedes) & 3. Class Diplopoda (millipedes)

Subphyla Mandibulata: Class Insecta  Insects typically have:  The three distinct segments (head, thorax, abdomen)  Three pairs of legs attached to the thorax  Mandibles  One pair of antennae  One pair of compound eyes  Two pairs of wings on the thorax  Tracheal tubes for respiration  Tracheal tubes open to the outside through small holes called spiracles