Bilateral Symmetry Protostomes Coelomates Jointed appendages Exoskeleton of Chitin All must “molt” All exhibit a form of Metamorphosis
All have three main body sections… a Head, a Thorax and an Abdomen
head mouthparts antennae compound eyes eyes HEAD The first body region is the head. Insect heads can be highly variable, but most possess eyes, antennae and mouthparts.
Antennae June beetle termite fly butterfly ant beetle Antennae are used by insects as major sensory devices, especially for smell, and can be adaptive for the insect in many ways.
Two Examples of Mouthparts chewingpiercing/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.
Picture of bodyparts Thorax The middle body region is called the thorax and is composed of three fused segments. All legs and wings are located on the thorax.
Abdomen The last body region is called the abdomen. It is composed of many segments connected by flexible sections allowing it great movement.
Class Insecta - Insects (6 legs) Class Arachnida – Spiders (8 legs) Class Crustacea – Crabs, etc..
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.
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
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 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. intestine
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
Some arthropods exchange gases through their “Body Surface”.Some arthropods exchange gases through their “Body Surface”. Some arthropods exchange gases through Trachea “air ducts”.Some arthropods exchange gases through Trachea “air ducts”. Some arthropods exchange gases through “Book Lungs”.Some arthropods exchange gases through “Book Lungs”. Some arthropods exchange gases through “Book Gills”.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
nerve bundles (ganglia) two lobed brain Nervous System 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.
Jointed AppendagesJointed Appendages Complex Muscular SystemComplex Muscular System
Locomotion: Well Developed Muscle System with an Exoskeleton of Chitin