Arthropods insects

Taxonomy Arthro- = joint Pod = foot Examples: spiders, insects, shrimp, lobster, crabs, millipedes, centipedes

General Characteristics The largest group of animals Have a hard exoskeleton made out of chiton Have jointed appendages for a wider range of motion Air is piped directly to cells for higher metabolism Demonstrate complex behavior patterns based on instinct

Body Plan Body Plan: Jointed appendages, segmented body, bilateral symmetry and exoskeleton made of chiton for protection Exoskeleton: hard outer covering that is sometimes molted exoskeleton molting horseshoe crab

Body Plan Segmentation: internally and externally segmented Each segment contains spiracles and nerves Head-thorax-abdomen or cephalothorax-abdomen Jointed appendages: jointed legs allow for more advanced movement and modification for a wider range of habitats Coelom: true body cavity filled with hemolymph (blood- like fluid)

Respiration Respiration: (spiracles) a system of air tubes that deliver oxygen directly to cells

Digestion Digestion: complete digestive system with specialized mouth parts and appendages (mandibles and palps) specialized for each food source

Circulation Circulation: Open circulatory system with a heart, arteries and hemolymph Hemocoel: the cavity that holds hemolymph fluid

Nervous System Nervous System: brain, nerve cords, ganglia and specialized sensory organs

Movement Movement: each arthropod has appendages that are specialized

Reproduction Reproduction: sexual reproduction: sexes are separate Fertilization is internal and then eggs are laid

Metamorphosis Metamorphosis: the changes in form that occur in an insects life cycle Incomplete: larva-nymph-adult Complete: larva-cocoon-adult butterflies

Ecological Importance Essential in food webs because they occupy every area on Earth Essential in the pollination of many plants Spread diseases (mosquitos, ticks) Create products like honey, silk and beeswax Are a food source for humans insect dye

Class Merostomata Only five living species Live in oceans but can swim up rivers Can spend time out of water Most ancient living arthropods Examples: horseshoe crabs

Horseshoe Crabs

Horseshoe Crabs

Class Pycnogonida Number of legs varies from 8-12 Found in all oceans and all temperatures Examples: Sea spiders

Class Branchiopoda 800 species Small: up to 10 cm long Examples: brine shrimp, Water fleas, tadpole shrimp, clam shrimp

Water Fleas

Water Fleas

Tadpole Shrimp

Brine Shrimp

Class Malacostraca Live in water Pets and food for humans Examples: Includes krill, sow bugs, lobsters, crayfish, shrimp, and crabs

Krill

Whale eating Krill

Krill

Krill

Lobsters

Shrimp

Crayfish

Crayfish

Crabs

red crabs Christmas island great migrations