1. Insects Crustaceans Arachnids
Arthropods
Insects
Crustaceans
Arachnids

2. Insects The study of insects is Entomology
Entomologists have described and classified more than 700,000 insect species.
Insects are so abundant that it is not surprising that they affect our lives in so many ways.

3. Arthropods ¾ of all animals belong to this phylum
Bilaterally symmetrical
True coelomates
Segmented
Examples:
Lobsters
Crabs
Crayfish
Spiders
Millipedes
Grasshoppers

4. Arthropod Characteristics
Arthropod means “jointed foot”
Have jointed appendages
Legs
Antennae
Exoskeleon
Cephalization-ventral nerve cord with brain (ganglia)
Compound eyes
Open circulatory systems

5. Molting
Exoskeleton can’t grow with developing body

6. Grasshoppers: External Structures
The insect is divided into three parts.
Head
Thorax
Abdomen

7. Feeding and digestion Herbivores Mandibles
Modified mouthparts for cutting and chewing leaves
Tear off bits
Maxillae
Hold and cut food
Labrum & Labium
Function like lips

8. Feeding and digestion Salivary glands to moisten food
Passes into the crop and gizzard from esophagus
Gizzard is used to shred the food
Passes into the digestive tracts:
Gastric ceca: pockets that secrete enzymes
Midgut
Hindgut
Anus

10. Respiration Have spiracles and tracheal tubes. Spiracles:
breathing pores/openings
Open to the tracheal tubes
diffusion of gases takes place

11. Circulation All insects have an open circulatory system.
Have a muscular heart that pumps hemolymph through the aorta

12. Excretion
Insects ingest through their mouth and excrete from their anus.
Insects have malpighian tubules, which get rid of nitrogen waste.
The wastes are released from the organism in the form of solid nitrogenous compounds.

13. Malpighian Tubules

14. Response Brain with a ventral nerve cord and ganglia on each segment
Antennae:
touch and smell
Compound eye:
sense movement, light and form images in many different directions
Simple eye (3):
sense light
They also have the ability to emit chemical pheromones.
They sense them through their antennae and their legs

15. Movement
Insects were the first organisms to evolve wings. They have separate muscles for their wings and their legs.
Insects are the only organisms that fly besides birds and bats.

16. Reproduction Have separate sexes
They utilize internal fertilization and reproduce sexually, most of the time.
Male deposits sperm into female’s seminal receptacle until egg is released from ovary
Ovipositor is used to lay eggs in dug soils

17. Metamorphosis
Incomplete
Egg, nymph and adult.

18. Metamorphosis
Complete Metamorphosis
Egg, larva, pupa and adult

19. Insect Communication
Insects use different sounds to mean different things.
They also have visual dances that have meanings.
They emit pheromones, which are chemicals that attract mates.

20. Grasshoppers