Subphylum: Hexapoda (insects) eg. roaches were the main insects of the time eg. some dragonflies had 2’ wingspans ~1.1 M species; probably millions more today insects have spread into all major habitats there are more species of insects than all other animal species dominant fauna of all freshwater and soil habitats à entire field of study = Entomology some live in deep underground caves most successful & widespread group of all life on top of world’s highest mountains adapted to land before most other terrestrial animals some insects live in unusual habitats: except for a few Chelicerates some flies occur by the millions in brine lakes eg. Great Salt (Devonian 390 MY) Lake, where hardly any other life forms are able to survive adaptations to land (even deserts): some insects live in hot springs up to 120º F (49º C) waxy cuticle varnish layer can close spiracles many species are found inside ice in anarctica extract & retain fluids from food and metabolism (some don’t need any liquid water at all) larvae of “petroleum flies” live in pools of petroleum around diapause & resistant eggs oil wells had 40 MY to evolve and diversify before serious a few insect species have been found breeding in brine vats competition for space and resources from other holding human cadavers at medical schools animal phyla the “short-circuit” beetle bores into lead cables à still no birds around yet but only a very few are truly marine; (Why?) à still not a lot of parasites of insects yet most are <2.5 cm (1/4”) by carboniferous (~300MY ago ) there many different àsmall size helps them escape enemies kinds of insects Animals: Arthropods-Hexapoda Ziser Lecture Notes, 2015.12 1 Animals: Arthropods-Hexapoda Ziser Lecture Notes, 2015.12 2 àneed very little food to sustain themselves A few kinds of insects have been semi-domesticated: range from < 1 mm to 25 cm honeybees eg. Atlas moth of India has a wingspan of almost 1 foot 3 trillion bees are kept and managed for pollenation and honey production eg. Walkingstick of India is up to 15” long silkworms (moth larvae spin coccoons of silk) insects invented agriculture & animal husbandry each coccoon is made from over a half mile of silk àmany ants and termites cultivate fungi within their burrows mealworms & crickets are used to feed pets (or humans) or for fishing bait à some ants guard aphids that let the ants “milk” them for nectar-like secretion Body Form st may have been 1 to invent slavery body in three parts: head, thorax and abdomen à there are ~35 species of “slave making ants” that regularly raid the nests of other ant species and take young back to Head their own colony large compound eyes there they work as they would in their home colony searching for food, raising young, etc several (usually 3) simple eyes (=ocelli) always very closely related species 1 pair of antennae ants will always do the work of whatever colony they are in when they emerge as adults many kinds of antennae were the first animals to fly eg. grasshoppers, crickets and cockroaches have long antennae à 130 MY before pterosaurs eg. butterflies have knob on end insects: 400 MY; devonian reptiles: 200 MY pterosaurs; late jurassic , eg. moths antennae are featherlike birds: 150 MY; coexisted with pterosaurs for~90MY bats: 54 MY (Eocene) Animals: Arthropods-Hexapoda Ziser Lecture Notes, 2015.12 3 Animals: Arthropods-Hexapoda Ziser Lecture Notes, 2015.12 4 antennae are very complex sense organs in which different segments control different wings are extensions of cuticle formed by aspects of an insects life: epidermis eg. in ants: Abdomen one segment detects nest odor and helps prevent an ant from entering the wrong colony segmented (10-11 segments) another segment identifies offspring of a specific queen reproductive organs another segment detects the ants own feeding females have pincher like or syringe like trail ovipositor to lay eggs another segment helps detect what is needed by the immature ants it is tending in some social insects it is modified into a stinger mandibles and other mouthparts for feeding Insect Movement Thorax most kinds of movement are created by muscular divided into three segments system (striated muscles like us) (pro- meso- & metathorax) insects have a more elaborate muscular system than à each with sclerites: any other invertebrate group tergum, pleura, sternum insects have more muscles than most animals including us each thoracic segment bears 1 pair of legs eg. humans have ~700 individual muscles; some insects have 900 or more muscle organs; some caterpillars à total 6 legs; thus hexapods have 4,000 most insects also have 2 pairs of wings on insects are remarkably strong, given their small size thorax Animals: Arthropods-Hexapoda Ziser Lecture Notes, 2015.12 5 Animals: Arthropods-Hexapoda Ziser Lecture Notes, 2015.12 6 eg. a bee can pick up 50 times its weight swimming (diving beetles, many insect larvae) eg. beetles are the strongest insects; up to 60 x’s their B. Wings weight [but their small size relative to weight makes them only appear strong most insects have two pairs of wings à if insects were as large as humans they would be little if any stronger than us] some use both pairs to fly (eg. butterflies) A. Legs some the 1st pair cover and protect second pair (eg. beetles) great diversity of leg types: a few have only 1 pair (flies, mosquitoes) insect legs are adapted for the same kinds of movements as vertebrates: a few are wingless (lice, fleas) walking, running, jumping, swimming, Insect Flight digging, climbing, grasping insects were the first animals to fly legs in 5 segments à 130 MY before any other animal sometimes modified for unsure of evolutionary origin of wings: jumping (grasshoppers, crickets, fleas) 1. originated as small flaps that first allowed gliding = “flying squirrel theory” eg. grasshoppers can jump 20 times length of st body 2. were 1 used as solar collectors to raise body temperature à equivalent jump for human would be 1/3rd length of football field later for gliding, then for flight eg. fleas are probably the best jumpers 3. originated from gills of aquatic forms many have can jump 8 “ high and 13 inches in length hinged gills on thorax à equivalent feat in human flying in most insects is like swimming for us à leap tall bldg in a single bound due to size and relative density of air storage of pollen (bees) wings are separate from legs and other Animals: Arthropods-Hexapoda Ziser Lecture Notes, 2015.12 7 Animals: Arthropods-Hexapoda Ziser Lecture Notes, 2015.12 8 appendages eg. the common housefly is one of most talented aerodynamicist on the planet don’t just move up and down à more maneuverable in flight than birds, bats or bees à common pattern resembles “butterfly eg. hoverflies are even better stroke” of human swimmers can make six turns a second direct and indirect flight muscles hover, fly strait up and down, backwards, do somersaults , land upsidedown etc the rate of wing beating varies considerably: yet: has brain smaller than a sesame seed fastest eg. midge >1000bps has only a dozen muscles for flying eg. housefly beat ~200bps eg. mosquito ~300bps but are loaded with sensors eg. honey bee ~ 190bps compound eyes wind sensitive hairs more typical beat: antennae eg. locust ~20bps three light sensors = ocelli eg. dragonfly ~25bps flight greatly improved dispersal ability slowly beating: eg. white butterfly ~12bps eg. swallowtail ~5bps some insects are able to migrate 1000’s of miles or fly at high altitudes: speed of insect flight also varies greatly: eg. monarch butterfly flies slowly (à 6 mph) from slowest insect flight speeds: but can fly 100’s of miles at a time eg. mosquitoes ~2mph eg. painted lady migrates 4000 miles eg. houseflies ~5 mph eg. butterflies ~6mph eg. some butterflies have been seen at 20,000’ eg. honey bee ~7 mph some wings are only temporary structures to quite fast eg. males and queen ants use wings only for mating flight, eg. hawkmoth ~35mph then they drop off eg. horse fly ~30mph eg. dragonflies à 25 mph Animals: Arthropods-Hexapoda Ziser Lecture Notes, 2015.12 9 Animals: Arthropods-Hexapoda Ziser Lecture Notes, 2015.12 10 Feeding & Nutrition d. some are predaceous insects feed upon almost every kind of organic substance e. some are parasitic most feed on plant juices and tissues the same basic mouthparts are modified in various = phytophagous ways to facilitate different methods of feeding: many feed on dead or decaying organic matter a. chewing mouthparts = saprophagous in many insects the mandibles are hardened into some are predaceous and attack other insects or “jaws” that are used to snip off pieces of plant or animal matter smaller invertebrates eg. many caterpillars feed on specific plants some are parasitic and feed on blood or living eg. dragonflies, some beetles have large strong tissues from temporary hosts mandibles b. siphoning mouthparts all insects share the same basic mouthparts: eg. butterflies & moths: the maxillae forms a long mandibles à jaws coiled food tube for sucking nectar hypopharynx à tongue labrum, labium à lips c. piercing mouthparts maxillae à helps to manipulate food eg. in biting flies the mouthparts resemble a beak for insects feed on a wide variety of foods: puncturing the skin eg. in mosquitoes, most of the mouthparts together a. most feed on plant juices and tissues form a long hollow tube, the labium directs this tube through the skin like a syringe to draw up blood b. others actually eat leaves, flowers and whole plants or animals d.