Phylum Arthropoda

Honey bees - good or bad? Are honey bees good or bad? They are good when they pollinate and produce honey, but bad when they sting.

Termites - good or bad? © 1998-2003 Troy Bartlett They are bad when they eat the wood in your house, but good when they break down dead and fallen trees.

Termites - good or bad? © 1998-2003 Troy Bartlett They are bad when they eat the wood in your house, but good when they break down dead and fallen trees.

General Characteristics Bilateral Symmetry Protostomes Coelomates Jointed appendages Exoskeleton of Chitin All must “molt” All exhibit a form of Metamorphosis Bilaterally symmetrical

All have three main body sections… a Head, a Thorax and an Abdomen

HEAD antennae compound eyes head mouthparts The first body region is the head. Insect heads can be highly variable, but most possess eyes, antennae and mouthparts. head mouthparts

Antennae are used by insects as major sensory beetle butterfly fly ant termite June beetle Antennae are used by insects as major sensory devices, especially for smell, and can be adaptive for the insect in many ways.

Insect mouthparts are also highly modified for the Two Examples of Mouthparts chewing piercing/sucking Insect mouthparts are also highly modified for the insect. Chewing, biting, or sucking, are a few examples. Mouthparts of an immature insect may differ from those of the same insect in its adult stage.

Thorax Picture of bodyparts The middle body region is called the thorax and is composed of three fused segments. All legs and wings are located on the thorax. Thorax

The last body region is called the abdomen The last body region is called the abdomen. It is composed of many segments connected by flexible sections allowing it great movement. Abdomen

Classification Class Insecta - Insects (6 legs) Class Arachnida – Spiders (8 legs) Class Crustacea – Crabs, etc.. Members are distinguished for having… ^

Reproduction Most are separate sexes. Fertilization is internal. Generally sexual, although some can reproduce parthenogenically. (reproduction without fertilization) Sex determination can be altered by a number of things. Some Arthropods develop through incomplete metamorphosis, some through complete metamorphosis. Sex determination can be altered by things such as: Environment age of female photoperiod size of host for parasitic arthropods number of matings

Incomplete Metamorphosis (immature forms are often called nymphs) Nymphs resemble the adult in form except for being smaller and lacking fully developed wings and sexual organs. Life Cycle: Egg --> nymph --> adult

Complete metamorphosis Immature forms are called larvae (larva, singular). The pupal stage is a transition stage, when the larva is transformed to the adult. Pupa molts to the adult form. Life Cycle: Egg --> larva --> pupa --> adult

Circulation Open Circulatory System Simple, one-chambered heart pumps blood through vessels into sinuses (chambers) and into the tissues…..blood returns to the heart through valved openings

Open Blood System The circulatory system is not composed of a central heart, veins and arteries which circulate blood cells and transport oxygen. The insect circulatory system is a simple tube (heart) down the back which is open at both ends and slowly pulses body fluids and nutrients from the rear of the insect to the head.

Digestive System of an Insect intestine The digestive system is a tube that opens at the mouth and empties at the tail end of the insect. It is divided into three parts called the foregut, midgut, and hind gut. In some insects such as the honey bee, the foregut acts as a crop to carry or hold liquids which can be regurgitated later.

Digestive System Mouth – opening to the digestive system Pharynx – common duct for air and food Esophagus – connects mouth to crop Crop – stores food Gizzard – grinds food Gastric Caeca – releases digestive enzymes Ventriculus – stores food Pyloric Valve – regulates flow of food Intestine – absorbs food into blood system Rectum – stores feces before discharge Anus – opening out of the digestive system

Respiration Some arthropods exchange gases through their “Body Surface”. Some arthropods exchange gases through Trachea “air ducts”. Some arthropods exchange gases through “Book Lungs”. Some arthropods exchange gases through “Book Gills”.

The respiratory system is composed of air sacs and tubes called tracheae. Air enters the tubes through a series of openings called spiracles found along the sides of the body. The largest spiracles are usually found on the thorax where greater musculature from wings and legs require more oxygen. There are no spiracles on the head.

Excretion in Insects Nitrogenous wastes are expelled as Uric Acid Crystals Mineral salts and Uric acid accumulates in the Malphigian Tubules and then transported to the intestines to be expelled through the anus

Nervous System two lobed brain nerve bundles (ganglia) Insects have a less centralized nervous system than humans. The nerve chord runs along the ventral or bottom of an insect. The brain is divided into two main parts. The largest lobes control important areas such as the eyes, antennae, and mouthparts. Other major concentrations of nerve bundles called ganglia occur along the nerve chord and usually control those body functions closest to it. two lobed brain nerve bundles (ganglia)

Complex Muscular System Locomotion Jointed Appendages Complex Muscular System

Locomotion: Well Developed Muscle System with an Exoskeleton of Chitin

Must Molt ( shed) in order to grow.

Habitats Live in most habitats Earth Sea Sky

Some even help keep arthropod population in check Importance to Environment Pollination Food for other animals Some even help keep arthropod population in check

Effect on Man Good Bad Food, clothing medicines protection from harmful organisms Bad devastating plagues famines

The End