Arthropods Ch. 13, pg. 374-382 382
Arthropods Insects Arachnids Centipedes and Millipedes Crustaceans
Characteristics of Arthropods Arthropods have jointed appendages and include legs, antennae, claws, and pincers. Arthropod appendages are adapted for capturing prey, feeding, mating, and sensing their environment.
Characteristics of Arthropods Arthropods have: Bilateral symmetry Segmented bodes An exoskeleton A body cavity A digestive system with two openings Nervous system
Segmented Bodies The bodies of arthropods are divided into segments. Some arthropods have many segments. Others have segments fused together to form body regions, such as those of insects, spiders, and crabs.
Exoskeletons All arthropods have a hard outer covering called an exoskeleton. Exoskeletons cover, support,, and protect the internal body and provides place for muscles to attach.
Exoskeleton An exoskeleton cannot grow as the animal grows. From time to time, the exoskeleton is shed and replaced by a new one in a process called molting.
Insects There are more than 700,000 species of insects. Insects have three body regions a head, a thorax, and an abdomen.
Insects- Head A insects head has a pair of antennae, eyes, and a mouth. The antennae is used for touch and smell.
Insect -Head The eyes are simple or compound. Simple eyes detect light and darkness. Compound eyes have many lenses and detect colors and movements. The mouthparts of insects vary.
Insects- Thorax An insect s s thorax contains three pairs of legs and one or two pairs of wings (if the insect has wings). Insects are the only invertebrate animal that can fly. Flying allows insects to find places to live, food sources,, and mates.
Insect- Abdomen An insect s s abdomen contains reproductive structures. Females lay thousands of eggs, but only a fraction develop into adults.
Insect Characteristics Insects have an open circulatory system that carries digested food to cells and removes wastes. Insect blood does not carry oxygen because it does not contain hemoglobin. Insects have openings called spiracles on the abdomen and thorax through which gas exchange occurs.
Insect Life Cycle Metamorphosis is a process in which many insect species change their body form to become adults.
Insect Life Cycle Metamorphosis can be complete and incomplete. Complete metamorphosis includes 4 stages: egg, larva, pupa, and adult.
Insect Life Cycle Insects that undergo complete metamorphosis are: butterflies, beetles, ants, bees, moths, and flies.
Insect Life Cycle Incomplete metamorphosis includes 3 stages: egg, nymph, and adult. Examples include: grasshoppers, silverfish, lice, and crickets.
Insects- Obtaining Food Insects feed on plants, the blood of animals, nectar, decaying materials, wood in houses, and clothes. Mouthparts are very diverse.
Insects- Obtaining Food Grasshoppers and ants have large mandibles for chewing plant tissue. Butterflies and honeybees have siphons for lapping up nectar in flowers. Mosquitoes have mouths that are adapted for piercing skin and sucking blood.
Insect Success Insects are extremely successful because of their tough, flexible, waterproof exoskeletons; their ability to fly; rapid reproductive cycles; ; and small sizes.
Arachnids Examples of Arachnids include: scorpions, spiders, mites and ticks.
Arachnids Arachnids have two body regions a head and a region called the cephalothorax. Arachnids have 4 pairs of legs and no antennae. Many arachnids are adapted to kill prey with poisen glands, stingers or fangs.
Scorpions Scorpions are arachnids that have a sharp, poison-filled stinger at the end of their abdomen. Scorpions have a pair of well-developed appendages pincers pincers with which they grab their prey.
Spiders Spiders cannot chew their food, so they release enzymes into their prey that help digest it. Gases are exchanged in book lungs. Openings in the abdomen allow the gases to move into the book lungs.
Mites Most mites are plant and animal parasites. However, some are not parasites. Some mites live in the follicles of human eyelashes. Most mites are so small that they look like tiny specs of dust.
Ticks All ticks are parasites. Ticks attach to their hosts through specialized mouthparts. Ticks often carry bacteria and viruses that can cause disease in other animals.
Centipedes and Millipedes Centipede Millipede
Centipedes and Millipedes Centipedes and Millipedes have long bodies with many segments Exoskeletons Jointed legs Antennae Simple eyes
Centipedes and Millipedes They can be found in damp environments, including wood piles, under vegetation,, and in basements. Centipedes and millipedes reproduce sexually. They make nests for their eggs and stay with them until they hatch.
Centipedes and Millipedes Centipedes hunt for prey, which include snails, slugs, and worms. Millipedes feed on plants and decaying material.
Crustaceans Crustaceans include crabs, crayfish, shrimp, barnacles, pill bugs, and water fleas. Water Flea Barnacle Pill Bug
Crustaceans Crustaceans have one or two pairs of antennae and mandibles,, which are used for crushing food. Most crustaceans live in water, except for pill bugs, which live in damp soil.
Crustaceans Crustaceans have five pairs of legs. The first pair are claws to catch and hold food. The other four pairs are walking legs.
Crustaceans Crustaceans have 5 pairs of appendages called swimmerets. Swimmerets help with movement and reproduction. Crustaceans have feathery gills for gas exchange. Crustaceans can also regenerate appendages.
Value of Arthropods Arthropods are a source of food for many animals. Insects pollinate crops which help produce food for humans. Arthropods produce products for humans like silk and honey.
Harmful Arthropods Arthropods can be pests and destroy food, clothing and property.
Harmful Arthropods Many arthropods such as mosquitoes, tsetse flies, fleas, and ticks carry diseases.
Controlling Insects One common way to control insects is insecticides. However many insecticides kill helpful insects as well as harmful ones. Insecticides can also pollute the environment.