The Arthropods Chapter 16

Phylum Arthropoda

Phylum Arthropoda Largest phylum in Kingdom Animalia Anthropoda means “jointed feet” Includes lobsters, spiders, scorpions, millipedes, and insects Can be harmful or helpful Harmful: destroy crops, eat other animals’ food, spread diseases Helpful: studied by engineers; control the numbers of harmful arthropods; help plants reproduce; make wax, honey, medicine, and silk

Phylum Arthropoda All arthropods have: Exoskeleton – their bones are outside of their body Chitin – allows the bones to be tough and flexible – they bend without breaking Arthropods molt – as they grow, their exoskeleton becomes too small – they outgrow the exoskeleton and throw it away Jointed appendages – their legs and feet have joints (bend) Body segmentation – most have 3 parts to their bodies Head Thorax (chest) Abdomen (belly) Open Circulatory System – they have a heart, but the blood goes into the body parts after leaving the heart (not veins) Ventral Nervous System – Ganglia (nerves) are located near the legs and connected to the brain by one cord

Nervous System Anatomy

Nervous System Anatomy Brain – located in the head Ganglia – nerves in the legs Ventral Nerve Cord – big nerve that connects the brain and the ganglia Antennae – come out of the head and do taste, smell, and touch Compound eyes – insects and crustaceans have these – able to see all around, not just a few directions ______ OR_________ Simple eyes – able to see very little, usually just light and dark

Subphylum Crustacea

Subphylum Crustacea Lobsters, crabs, crayfish, shrimp Kingdom Animalia, Subkingdom Invertebrates, Phylum Anthropoda, Subphylum Crustacea Usually live in the water Carapace – the back plate of a lobster (the front has 6 plates) Scavengers: they eat anything! They grind their food into powder using the gastric mill. They can regenerate (grow new parts) Reproduce sexually – male gives sperm to the female in the fall, female lays eggs in the spring that hatch in the summer

Subphylum Chelicerata

Subphylum Chelicerata 3 classes: Arachnida is the most important class Arachnids have: 8 legs – 2 of these are pedipalps (legs used for sensing and mating instead of walking) 2 major segments Cephalothorax (head-chest) abdomen No antennae or mandibles (jaws) Have chelicerae instead (mouth that looks like fangs) Respiration by book lungs Breathe through their stomachs Usually 4 pair of simple eyes (8 eyes) Reproduce sexually – females are usually larger than males

Other Arachnids Scorpions, mites, and ticks

Class Insecta

Class Insecta 80% of all animals are insects (bugs) There are 31 orders under Class Insecta Structure of Insects: Three pairs of legs (six legs) Usually have wings 3 segments to the body Head Thorax (chest) Abdomen One pair of sensory antennae (2 of them)

Wings of Insects M0st insects have 2 pairs (4) wings Kinds of wings: Membranous wings: thin, transparent (see through) – most common kind of wing - like a dragonfly or a bee Scale-covered wings: butterflies and moths

Wings of Insects Continued: Leatherlike wings: extra set of wings that protects the wings used to fly – like a cover for wings – grasshoppers have these Horny wings: ladybug wings – thick, protect the smaller wings, cover the back of the bug

Digestion (eating) of Insects Mouth: Upper lip - labrum Mandibles - used for chewing Maxillae – put food into the mouth Lower lip – labium Stomach: Foregut – behind the mouth – this is where salivary glands get the food wet with spit before going to the gizzard to be ground up into powder Midgut – where the stomach is – gastric ceca put more digestive juices onto the food Hindgut – place right before the food is excreted (pooped)

Respiration, Circulation, Excretion and Reproduction Respiration: insects breathe in their abdomens through tubes called spiracles Circulation: the insects heart pumps blood into the abdomen, where it covers the organs – no veins Excretion: Malpighian tubules are straws that pull nitrogen out of the insect and put it into the intestines, where it will become poop Reproduction: Sexual reproduction The male puts sperm in the female The female then lays eggs that will hatch later

Metamorphosis in Insects Metamorphosis means changing from a baby to an adult There are two kinds of metamorphosis: Incomplete metamorphosis (3 stages) Grasshoppers, cicadas, and true bugs Egg Nymph (teenager – looks like a small adult) – only for insects that stay on land (cicadas) OR Naiad – teenager that doesn’t look like the adult and lives in the water (grasshoppers) Adult – the bug

Incomplete Metamorphosis

Metamorphosis Complete metamorphosis (4 stages) Most insects – butterflies, flies, beetles, mosquitoes Eggs Larva – like a little worm (maggots, grubs, wigglers, caterpillars) – childhood bug Pupa – teenager insect – usually inside a case called a cocoon Adult – the bug

Complete Metamorphosis