Crustaceans, Spiders and Insects

Arthropods are the most successful phylum on the planet! 750,000 species Arthropods have Segmented body Tough exoskeleton Jointed appendages

Feeding – complex mouthparts to eat a wide range of food Respiration Land – air enters through spiracles – holes in the side of the body. Water – gills or book gills Circulation – open circulatory system – open sinuses Excretion – Malpighian tubules – saclike organ that combines urine and waste together Response – have a brain! Sophisticated eyes and taste receptors Movement – have muscles…can flex and extend Reproduction – internal or external reproduction depending on the species

1. Crustaceans – primarily aquatic Examples: crabs, shrimps, crayfishes and pillbugs. Characteristics:  Two pairs of antennae  2 or 3 body sections – Cephalothorax/Abdomen  Chewing mouthparts called mandibles

Molting – when arthropods outgrow their exoskeleton Steps to molting 1. skin glands digest inner part of exoskeleton 2. other glands create a new exoskeleton 3. animal pulls itself out of old skeleton 4. While new skeleton is soft – animal fills it with air to allow for growth

2. Spiders and their relatives Characteristics No antennae Cephalothorax and abdomen 2 pairs of mouthpart appendages Chelicerae – fangs to stab and paralyze prey Pedipalps – grab prey Spiders are in the class Arachnida Spiders have no jaws so they liquify their prey Scorpions are found in warm climates. The abdomen has a stinger that can kill and paralyze prey.

3. Insects – There are 3 classes of Insects 1. Chilopoda – centipedes 2. Diplopoda – millipedes 3. Insecta – the insects 1. Centipedes – each body segment has one pair of legs carnivores live beneath rocks or in the soil 2. Millipedes – each body segment has two pairs of legs Dragon Millipede – produces cyanide when threatened.

Insects have a body divided into three parts Head – antennae and eyes Thorax - three pairs of legs, wings Abdomen – stinger or poison gland

Insects undergo metamorphosis – a process of changing shape and form. 1. Incomplete Metamorphosis – Young (called nymphs) look very much like the adults. Examples: Grasshoppers

2. Complete metamorphosis – dramatic change in body form. Eggs—Larvae—Pupa—Adult Examples: bees, moths, beetles, butterflies, flies