Myriapoda and Hexapoda

Characteristics n Enormously successful n 1 million + species n Many undescribed n 75% of all living species

Characteristics n Insect dominance –Waxy epicuticle –Flight

Sub Phylum Myriapoda n Four Classes n Two Body Tagmata –Head –Trunk –Uniramous appendages –Terrestrial

Class Diplopoda n Class Diplopoda – Millipedes 11 to 100 trunk segments 2 appendages per trunk segment

Class Diplopoda Most are round in shape Live all over the world Low level of wax on epicuticle

Class Diplopoda Eat dead and decaying plant material (detritivores) Roll into a ball –Prevent desiccation –Defense

Class Diplopoda Repugnatorial glands –Hydrogen Cyanide production Gain appendages and segments as they molt

Class Chilopoda n Class Chilopoda –Centipedes Nocturnal One pair of appendages per trunk segment 15 or more segments

Class Chilopoda Last pair of appendages are used as sensory appartus Flat body Eat small arthropods, earthworms, and snails or frogs and rodents

Class Chilopoda Poison claws are modified first appendages Fast for their size Large tropical species can kill humans

Class Pauropoda n Class Pauropoda –Soft bodied animals –11 segments –Feed on fungi and decaying plant matter

Class Symphyla n Class Symphyla –Three tagmata –No eyes –12 segments with single pairs of legs

Subphylum Hexapoda n Two Classes n Three Tagmata –Five head appendages –Three pairs of legs on each thorax

Class Entognatha (springtails) n mouthparts are entognathous, meaning they are retracted within the head. n Entognatha are apterous, meaning they lack wings. n hexapodous condition of these animals has evolved independently from that of insects n Can live in arctic conditions

Class Insecta n Class Insecta –Most successful land animals One pair of antenae Wings Three pairs of legs

Class Insecta –External Structure Three tagmata –Head »Single pair of antennae »Compound eyes »Sometimes ocelli

Class Insecta –Thorax »Three segments - prothorax, mesothorax, and metathorax »Wings with veins

Class Insecta –Abdomen »10 to 11 segments »Lateral folds to allow for expansion »Spiracles lead to tracheal system

Class Insecta – Flight Insects were the first animals to fly Wings are thought to have come from protective coverings

Class Insecta Direct or synchronous flight –Grasshopper, butterflies, and dragonflies –Muscles at the base of wings and on the exoskeleton

Class Insecta Indirect or asynchronous flight –Flies and wasps –Muscles change the shape of the exoskeleton »Fibillar flight muscles

Class Insecta –Other Locomotion Walk, swim, run, or jump Cockroach reaches speeds of 5km/hr. Fleas can jump 100 times their size

Class Insecta –Nutrition Three segment gut

Class Insecta –Biting Mouthparts Labrum – upper lip –Sensory Mandible – Chewing (teeth) Maxillae – cutting surface, sensory Labrium – Sensory lower lip Hypopharynx – tongue- like structure –Grasshoppers

Now these are some mandibles!

Class Insecta Sucking Mouthparts –Mosquitoes

Class Insecta n Sponging Mouthparts –Labellum – modified labium –Saliva is secreted –Mouth sponges up liquid Flies Essentially laps up slobber and digested food.

Class Insecta – Gas Exchange Trachea open to spiracles Store bicarbonate Aquatic insects diffuse straight to water (gills)

Class Insecta n Circulation –Open circulatory system –Amoeboid cells –Ectotherms or heterotherms Shivering Thermogenesis

Class Insecta n Nervous –Similar to annelids –Some can learn –Setae and mechanoreceptors Johnston’s Organs— in antennae---motion Tympanal Organs--- hearing

Class Insecta n Excretion –Malphigian tubules— waste removal –Uric acid

Class Insecta n Chemical regulation –Controls many functions— Juvenile hormone/ –ecdysone –Pheromones

Ecdysis or molting

Class Insecta n Reproduction –Controlled by a number of factors Food, photoperiod, population density, temperature, and humidity –Indirect fertilization Silverfish and springtails

Class Insecta n Metamorphosis »Ametabolous metamorphosis— no metamorphasis »Hemimetabolous metamorphosis- --partial metamorphosis --- egg--- nymph---adult »Holometabolous metamorphosis-- -whole metamorphosis egg--- larvae---pupa---adult

Class Insecta – Insect Behavior Most innate Social qualities –Castes (soldier, worker, queen etc.)

Class Insecta n Only 0.5% harmful to humans n 65% pollinate plants n Control qualities n Some parasitic –Lice, fleas