Arthropods contin… …..or “the most successful animals of all time”.

Quick Review…..

Main Characteristics Jointed appendages Segmented body Exoskeleton (skeleton on outside) Mandibles – chewing mouthparts Metamorphosis ( egg - larva - adult) Classification Kingdom Animalia , Phylum Arthropoda          

Common Features of Arthropods Molting: shedding of cuticle in order to secrete a larger one. Makes the arthropod vulnerable. Open circulatory system: blood flows through open spaces. Malpighian tubules: excretory organs that remove waste from blood in the circulatory system (most arthropods)

Unique Arthropod Features (cont.) Antennae: sensory organs that come in pairs on the organism’s head Compound eyes: eyes with many parts and multiple separate focusing elements

Bilateral Symmetry

Chelicerates Spiders, ticks and scorpions 2 body segments                         cephalothorax, abdomen 8 legs No antenna Spiders belong to a special group called *Arachnids

Brown recluse bites cause necrosis (death of tissue).

Fisher Spider: Catches prey, paralyzes them, pumps in digestive enzymes, then sucks out predigested contents.

Are spiders really dangerous? Most people fear spiders without good reason Spiders are allies of humans in our battle with pest insects Spiders are food for other organisms. Spider venoms show promise in the field of medicine. Spider silk is among the strongest, most elastic of natural fibers. Synthesized spider silk has created strong parachutes and bullet-proof vests

Crustaceans Shrimp, lobsters, crabs, crayfish 4 pairs of legs 2 claws (chelipeds) 2 pair of antennae

Subphylum Uniramia Millipedes Centipedes Insects

Centipedes & Millipedes Predators, poisonous 1 pair of legs per segment Millipedes Herbivores 2 pair of legs per segment

Insects 3 pairs of legs 1 pair of antennae 3 body segments (head, thorax, abdomen) Compound eyes

Respiration: Spiracles: openings in exoskeleton that allow air to enter tracheal system (insects only)

Reproduction Life Cycle Metamorphosis: process of changing shape and form

Incomplete Metamorphosis Young are similar to adults, but have different body proportions and are smaller. There are a series of molts that eventually lead to the organism reaching full size. Adult -> egg -> nymph -> nymph -> adult… •Nymph is a ___________

Complete Metamorphosis There are several distinct stages: Larval stage - specialized for eating and growing Pupal Stage - actual change occurs Adult stage - specialized for reproduction

Beneficial Insects More than 100,000 species of insects are found almost everywhere in North America, but very few are harmful. Insects are important to the food chain, pollination, honey, wax, shellac, silk, food, scavenging, and decomposing.

Save the Bees from Colony Collapse Disorder https://www.youtube.com/watch?v=oVtDHihoFwM Pollinators Waggle Dance

Review Questions What type of symmetry do arthropods have? In what stage of metamorphosis does abrupt change occur? What do most spiders use to breathe? What process allows arthropods to shed their cuticle in order to grow a larger one?