PHYLUM ARTHROPODA

Arthropoda Characteristics account for over 80% of all living animal species

Arthropoda Characteristics means “jointed foot” True coelom exoskeleton made of chitin show a high degree of cephalization variety of segmented antennae used for sensing the environment and detecting chemicals most have compound eyes & other light sensing structures body plan of repeated segments that attach to an appendage

Arthropoda Characteristics open circulatory system Heart pumps circulatory fluid thru vessels that empty into spaces in the body nervous system is ladder-like with brain formed from fused ganglia Respiratory system varies with each species.

Life cycle Stage 1: Egg – females lay thousands of eggs. Some # survive Stage 2: juvenile each has different names to describe this stage (example: lice – nymph) Stage 3: Molting – shedding or physical change before adulthood Stage 4: Adulthood – those surviving can reproduce. Most fertilization of eggs inside female then released to hatch.

Phylum Arthropoda classes 5 major classes: Chilopoda – centipedes Diplopoda – millipedes Crustacea – crabs, lobster, crayfish,shrimp Insecta – insects Arachnida – spiders, scorpions, mites, chiggers

Classification of Arhtropoda Centipedes – 1 pr legs/segment Millipedes – 2 prs legs/segment Crustaceans – 5 pairs of legs Insects – 3 pairs of legs Arachnids – 4 pairs of legs

Class Diplopoda 1000 leggers millipede Cylindrical worm-like with 2/prs legs/seg. Juveniles may possess only 1 pair per segment Simple eyes if any present. Many have no eyes Decomposers or herbivores Short antenna Non-toxic

Diplopoda Characteristics Very timid Protect by rolling themselves up tight and discharge a foul smelling, distasteful substance. Fertilized eggs are laid in the soil. They are found in cool, moist environments. Found under rocks and logs.

Class Diplopoda

Class Chilopoda Centipedes 100 leggers Flattened worm like w/1 pr legs/seg Carnivores Possess a pair of poison claws or legs just behind the head which are used to paralyze their prey Feed on insects or small animals Most centipedes are beneficial Large species found in the tropics (length of up to 18 inches) Can inflict painful bites

More Chilopoda characteristics Simple eyes The bite of centipedes can be painful to humans but not deadly. Life Cycle: Males spin web where they deposit sperm for females to pick up. Sometimes there is a courtship of dancing or tapping. Habitat: Like millipedes can be found under rocks, logs, or bark of tree.

Class Chilopoda

Class Insecta Upwards of 3 million species Outnumber all other plant and animal groups Found in all environments Some fly hundreds of KM per week

Class Insecta Three body divisions Head Thorax Abdomen 12 Inches—Largest 1MM-Smallest Rapid growth rate Most mature < 1 year Display almost every color

Class Insecta Spiracles (external openings) along abdomen used for breathing Highly modified mouth parts (mandibles) Some beetles can chew through lead or zinc Well developed tube within a tube digestive system Well developed nervous system Sight: two types of eyes (Ocelli and compound eyes) Smell/taste-Use of antennae and feet Hearing- tympanum (eardrum)

Defense Insects use can use a variety of defenses: Hiding Burrowing Mimicry Shedding appendages Chemical defense Camouflage Warning colors

Insects and the Economy Insects have direct impact on agricultural food production Chewing leaves Sucking out plant juices Boring into roots Spreading plant pathogens Can transmit diseases

Benefits Insects play a role in the cycle of nutrients on Earth. Help aerate soil Improve soils retention of rainwater As parasites and predators help with community stability prevents over population growth Insects help pollinate Other benefits: Produce honey to eat Beeswax Silk from silkworms

Insect Reproduction Reproduction is most often sexual Parthenogenesis is asexual reproduction – species can form from unfertilized eggs. Example bees – unfertilized produce males, fertilized can produce females Females: Make eggs Receive sperm and store it Able to manipulate sperm from different males Number of eggs an insect lays can vary Males: Reproductive system consists of testis

Class Insecta Pheromones- External hormones used for communication (especially in finding mates)

Crustacea Body segmented with hardened Limbs Limbs generally with two branches Two pairs of antennae Two compound eyes (eyes with many lenses) Body with 7 or more pairs of sometimes very different appendages for feeding, locomotion and sex Respiration by gills Nauplius- Distinctive larval stage with three pairs of branched appendages Although originally aquatic, many crustaceans are adapted to life on land

Crustacea Shrimp Lobster Krill Pill bug Crabs Crayfish Barnacles (sessile)

Crustacea http://www.youtube.com/watch?v=eKPrGxB1Kzc

Class Arachnida Spiders Mites/ticks Scorpions

Class Arachnida Many, but not all spiders web builders Liquid feeders Most familiar spiders head (fused to thorax) and abdomen All toxic No antennae Many, but not all spiders web builders Liquid feeders Inject digestive enzymes into prey and drink juices Use powerful jaws to crush exoskeleton- then digest and eat

Class Arachnida