• most diverse group of invertebrates (1,130,000 species)

• 75% of all animal species

• jointed appendages – important characteristic

• - adapted for walking, feeding, sensing, and mating

• hard, thick, and made out of a carbohydrate called chitin

• land arthropods must have a waxy layer to protect against water loss

• Molting = shedding of the old exoskeleton

• molts need to occur for arthropod to increase in size or add appendages (legs)

• new, softer exoskeleton forms underneath old skeleton

• new exoskeleton will harden overtime

• 3 fused segments:

• 1. head 2. thorax 3.abdomen

( fusion allows for better movement and protection)

• some arthropods have a fused head and thorax called a cephalothorax

Three types:

1.Gills

- aquatic arthropods

2. Book lungs

- spiders, horseshoe crab

- leaf-like plates filled w/ air

3. Tracheal tubes

- terrestrial insects

- branching network of hollow air passages

All respiration based on diffusion of gases (Oxygen/Carbon dioxide)

• Antennae -- detect movement, sound and chemicals; used for communication (moth, mosquito, bee)

• pheromones --chemical odor signals can be given off for communication

• Usually - one pair of compound eyes and 3-8 simple eyes

• simple eye = one lens used for detecting light

• compound eye = many lenses, detect movements and colors

• Consists of 2 ventral nerve cords, anterior “brain”, and several ganglia

• ganglia serve as control centers for specific body sections

• Open system, blood pumped by one or more hearts

• heartvessels tissues heart (through open body spaces)

• Complete gut

• mouth parts called mandibles (jaws)

• adapted for chewing, holding, sucking, or biting

• spiders have chelicerae, 1st appendage adapted for piercing or fangs

• spiders and crustaceans also have pedipalps, used for holding food, sensing, and even mating

Insect Digestive Tract

Esophagus Crop Gizzard Salivary gland Gastric ceaca Midgut Intestine Rectum anus

• Use Malphigian Tubules

• located in abdomen

• empty into intestine

• Muscles attached to inner surface of exoskeleton

• External fertilization– aquatic (water)

• Internal fertilization– terrestrial (land)

• some species exhibit parthenogenesis (asexual reproduction—new insect develops from an unfertilized egg.) ex. Bees, ants, wasps

Incomplete Metamorphosisegg, nymph, adult

Grasshopper Anatomy

http://webs.lander.edu/rsfox/invertebrates/romalea.html

http://www.carolina.com/category/teacher+resources/dissection+activities+and+resources/grasshopper+dissection.do

Above is excellent picture

http://bugs.osu.edu/~bugdoc/Shetlar/462/462InsectMorphology/Morph03.htm

http://www.junglewalk.com/video/Grasshopper-movie.htm

http://insects.tamu.edu/imagegallery/video/

http://salinella.bio.uottawa.ca/digitalzoology/Arthropo/Default.php?FlashLabModule.swf?&Loadmoviename=../ArthTrac/Inse_Hopp_05_lb.swf?E?Md2ChapterMcp1?Md2Ch4SectionMcp1?Md2Ch4Sc2TopicMcp1

http://www.members.shaw.ca/jonesbiology1/bio11/units/ecology/grasshopperdissectionlab.PDF

Above anatomy of digestive tract