BIO 402: Field Biology Bumblebee on thistle Sumter National Forest May 2005

 JumpStart – September 7, 2010

Arthropods are characterized by:  Exoskeleton of chitin (must molt to grow)  Jointed legs  Segmented body  Variable number of antennae for senses  Breath through a number of branching tubules marine crab at Riverbanks Zoo

Two major subphyla are: Subphylum Chelicerata (chelicerates)  no antennae  mouth parts with chelicerae  at least five pair of legs or leg-like appendages  two distinct body segments Include: horseshoe crab, sea spiders, arachnids

Sea spider (above) Brown recluse spider(right) Horseshoe crab (below)

 Subphylum Mandibulata (mandibulates)  Have antennae  Mouthy parts with mandibles  Widely variable number appendages  Variable number of body segments Include: crustaceans, millipedes, centipedes and insects

Mosquito (ul) Millipede (ur) Centipede (ll) Crayfish (lr)

Trivia about insects:  Over 1 million species worldwide 90% are in the tropics  About 13,000 species in North Carolina  About 10,000 species in South Carolina Stag Beetle

 Three body segments (head, thorax, abdomen)  One pair antennae  Mouth parts containing a labrum, pair of mandibles, pair of maxillae, a hypopharynx and a labium  Three pair of legs  Often 1-2 pair of wings (attached to thorax)  A gonopore at posterior end of abdomen  No locomotor segments on the abdomen

 Insects grow by molting, commonly resulting in change  Process leads to metamorphosis

Several types of metamorphosis  Simple – gets large with each molt  Gradual – slow development of wings and other structures  Incomplete – last molt dramatic: aquatic to terrestrial life  Complete – larvae  pupae  adult larval forms commonly hard to identify

We will look at the following components:  Head  Body plates  Thorax  Wings  Legs  Abdomen

Compound eyes typically present  positioned above or behind the antennae  variation present in: size, shape, color Ocelli also present –  are small, simple eyes located between or above the antennae & compound eyes  1-3 in number

A number of different types of antennae are present  some are long and of one segment (butterflies)  some have may segments (beetles)  may also be clubbed (increase in diameter toward apex)

Mouth parts important  LABRUM - "upper lip"; broad & flap-like  MANDIBLES - heavily sclerotized, commonly tooth-like and nonsegmented - mostly for chewing - modified in some, long & skinny (true bugs)  MAXILLAE - pseudotooth-like, segmented - include extentions, palps - modified by some to be long & tubular = stylets  LABIUM - "lower lips"; broad, flap-like  HYPOPHARYNX - tongue-like structure

 In most cases all the head plates are fused into one structure - can see divisions as sutures  Essentially all insects have one pair antennae - variation important in taxonomy: a) number segments b) overall length relative to heard size c) presence of a capitate apex

Three distinct positions:  tergum – upper, dorsal  pleuron – lateral  sternum – lower, ventral

 Three segments, a pair of legs on each - prothorax: 1st pair legs (no wings) - mesothorax: 2nd pair legs + 1st pair wings - metathorax: 3rd pair legs + 2nd pair wings  Upper or dorsal surface = pronotum, mesonotum, metanotum commonly a large segment of metanotum between wings differs = scutellum, commonly will be triangular  Openings to tracheal system common on lateral meso- & metathorax (called spiracles)

 Have either one or two pair - Are outgrowths of the body cavity - Many wings are membranous and have a venation pattern  Wing movement produced by change in thorax shape  Very important in identification of insects

 Number of veins present (anterior to posterior) Costa (C) - along leading edge of wings Subcosta (Sc) Radius (R) - commonly branched, R1, R2, etc. Median (M) - almost always branched once anterior (MA), posterior (MP) Cubital plical (CuP) - Plical (Pl) and Vannals (V) - some groups these as the Anals (A)

 Veins connecting between the main veins are the cross veins  These have names in some groups, as lower case letters - humeral (h) - radial (r) - sectorial (s) - radio-medial (r-m) - bmedial (m) - medio-cubital (m-cu)  The number of cross veins varies greatly - dragonflies (Odonata) with many

All have the following (from base to apex)  Coxa (coxae) - typically small  Trochanter - typically small  Femur (femora) - typically the longer  Tibia (tibiae) - typically the longer tip commonly has a spur (tympanum of crickets & some grasshoppers)  Tarsus (tarsi) - commonly with 3-5 tarsomeres (lobes or parts) - the last typically has the claw(s) - also with a pad = pulvillus

 Much variation present in size & shape of segments  Commonly may see: - spines: rigid bristles - setae: flexible hairs

 Of eleven segments typically only 7-8 visible 1st obscured by thorax last modified for reproductive functions  Many have tympanum on the first abdomenal segment (hearing)  Spiracles commonly quite visible on the pleuron  Some Orders with posterior cerci (pair - ex. Orthoptera) or caudal filament (one) some with all three (the silverfish, Thysanura)  Reproductive structures may be quit evident females with ovipositor and/or clapser

 A number of variations in morphology may make identification hard  Upon death changes occur - drying causes them to shrink - alcohol causes them to expand  General color variation from one location to another

 Immature forms of primitive orders will have shorter wings, etc.  Newly emerged adults may have disproportionate 1) size ratios 2) colors  Difference may also be due to sexual dimorphism