Myriapods, Hexapods

Subphylum Hexapoda + Subphylum Myriapoda (primarily) terrestrial mandibulates Paired mouthparts- chewing/grinding/tearing Homopteran Orthopteran movie

Subphylum Hexapoda + Subphylum Myriapoda Uniramous (unbranched) appendages Biramous appendage

Subphylum Hexapoda + Subphylum Myriapoda One pair of antennae

Subphylum Hexapoda + Subphylum Myriapoda Use tracheae to carry respiratory gasses Chitin-lined invaginations of epithelium Open to the outside via spiracles Chitin- lined to reduce water loss

Subphylum Hexapoda + Subphylum Myriapoda Excretion by Malpighian tubules Almost all insects, some myriapods, some spiders Nitrogenous waste (ammonia) removed by converting into uric acid. Energy costly. In aquatic insects, ammonia simply diffuses out of the body into surrounding water. Excretion of uric acid minimizes water loss. Nearly half of the food energy a terrestrial insect consumes may be used to process metabolic wastes. Some water, ions, organic compounds are reabsorbed in the basal portion of the Malppighian tubules and the hindgut; the rest are reabsorbed in the rectum. Uric acid moves into the hindgut and is excreted

Excretion by Malpighian tubules (cont’d) Blind-ended tubules bathed in hemolymph Remove nitrogenous waste (e.g. uric acid), amino acids, sugars Nitrogenous waste (ammonia) removed by converting into uric acid. Energy costly. In aquatic insects, ammonia simply diffuses out of the body into surrounding water. Excretion of uric acid minimizes water loss. Nearly half of the food energy a terrestrial insect consumes may be used to process metabolic wastes. Some water, ions, organic compounds are reabsorbed in the basal portion of the Malppighian tubules and the hindgut; the rest are reabsorbed in the rectum. Uric acid moves into the hindgut and is excreted

Excretion by Malpighian tubules (cont’d) Minerals, water resorbed at bottom of tubule and by rectal glands of hindgut waste passed out Nitrogenous waste (ammonia) removed by converting into uric acid. Energy costly. In aquatic insects, ammonia simply diffuses out of the body into surrounding water. Excretion of uric acid minimizes water loss. Nearly half of the food energy a terrestrial insect consumes may be used to process metabolic wastes. Some water, ions, organic compounds are reabsorbed in the basal portion of the Malppighian tubules and the hindgut; the rest are reabsorbed in the rectum. Uric acid moves into the hindgut and is excreted

Myriapods

Subphylum Myriapoda “many footed” Class Chilopoda Class Diplopoda

Class Chilopoda centipedes Serial segmented, flattened body each segment has a pair of jointed appendages

Class Chilopoda (cont’d) Active predators kill prey with poison claws and fangs (modified legs on first segment)

Class Diplopoda Millipedes Serially segmented, rounded body

Class Diplopoda 2 smaller pairs of legs per segment Slow moving; feed on decaying plants movie

Subphylum Hexapoda Includes Class Insecta Beetles, grasshoppers, butterflies, flies, bees… Movie movie

Class Insecta

Most Abundant and Diverse Animal Class 1,000,000+ species identified May as many as 10,000,000 More than all other animals combined

Distribution of Insects Air land In the soil Parasites Plants Animals Freshwater

Reasons for insect success Small size Reproductive potential Co-evolution with plants Evolution of flight Metamorphosis

Characteristics of Insects Three body regions Head Thorax Abdomen Three pair of legs

Characteristics (cont) wings Absent in some Pair of compound eyes Spiracles for respiration

External Structure of a Generalized Insect Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. External Structure of a Generalized Insect

Internal Structure of a Generalized Insect Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Internal Structure of a Generalized Insect Fig. 15.8 15-6

External structure of insects Head one pair of antennae

External structure of insects Head pair of compound eyes (detect movement) several sets of simple eyes= ocelli (probably detect changes in light intensity) Mosquito compound eye

External structure of insects (cont’d) Head Antennae can be highly variable Mosquito antennae

External structure of insects (cont’d) Mouthparts are highly modified depending on the type of insect for piercing and sucking (ie. mosquitos) movie

External structure of insects (cont’d) Mouthparts are highly modified depending on the type of insect for chewing (ie. grasshoppers) movie

External structure of insects (cont’d) Mouthparts are highly modified depending on the type of insect for siphoning (ie. butterflies) movie

External structure of insects (cont’d) Mouthparts are highly modified depending on the type of insect for sponging (ie. flies) Movie damselfly eating moth

External structure of insects (cont’d) Thorax consists of three regions: Prothorax (anterior-most segment) Mesothorax Metathorax One pair of legs attaches along ventral margin of each thoracic region

External structure of insects (cont’d) Insects may have 1 pair, 2 pair, or no wings Insects are the only invertebrates that can fly movie Drosophila melanogaster Archaeognatha (bristletail)

Wings of insects= modified exoskeleton 1st pair is often tough and leathery (protection) fold over the inner pair .

Attach to mesothorax and metathorax Have thickened, hollow veins for increased strength .

Abdomen does not have appendages

Abdomen terminal portions harbor the reproductive structures

Insects undergo metamorphosis

Metamorphosis Change in form from one developmental stage to another Yellow bear caterpillar Change in form from one developmental stage to another Immature and adult body forms May not compete May be incomplete or complete Monarch butterfly chrysalis Apollo butterfly

Incomplete Metamorphosis cockroach Early developmental stages very similar to adults only the wings and reproductive structures gradually develop

Incomplete metamorphosis (cont’d) cockroach The immature stages = nymphs egg---> nymphs ----> adult

Complete metamorphosis Each stage is structurally and functionally very different

Complete metamorphosis (cont’d) The egg develops into an immature larva; eats voraciously movie

Complete metamorphosis (cont’d) Followed by a transitional stage - pupa, contained within cocoon

Complete metamorphosis (cont’d) Metamorphosis occurs within the pupal exoskeleton, yielding a sexually mature adult movie

Beneficial Insects Honey bee Honey Pollinates crops

Beneficial Insects Silkworm moth Lava produces silk

Beneficial Insects Breakdown dung

Beneficial Insects Blow fly Decompose dead bodies

Beneficial Insects Lady bug Eats harmful insects Saved California citrus in ’20s

Beneficial Insects Some wasps Kill harmful insects movie Parasitoid Larvae live in body of host, eventually killing it movie

Fruit Fly Drosophila Genetics research

Some genes are highly conserved among organisms NCBI From Molecular cell biology 5e, Lodish

Harmful Insects Boll weevil Destroys cotton

Harmful Insects Tent caterpillar Pest of many trees and shrubs

Harmful Insects Mosquitos Vector Malaria Yellow fever Encephalitis West Nile virus Movie Web-linked movie, better

Harmful Insects Flea Vector for Plague Xenopsylla Cheopis

Xenopsylla Cheopis Rat flea Vector for plague

Black Death Bubonic plague 1357-1350 killed 25,000,000 in Europe 1900’s killed 20,000,000 in India

Plague Survivor

Alexandre Yersin Discovered bacterium Yersinia pestis Treated with antibiotics