Arthropods II. Insect origins Flashcards
Describe Crustacea
- paraphyletic
- Subphylum in the Phylum Arthropoda
- all Pancrustacea that are not Hexapods
Hexapods
evolved from a crustacean ancestor
Describe the Pancrustacea
Crustaceans and Hexapods together
Hexapoda emerged
~470 mya
Insects emerged
~400 mya
Describe the six major crustacean Classes
- Cephalocarida
- Remipedia
- Malacostraca & Maxillopoda
- Branchiopoda
- Ostracoda
- Maxillopoda
Cephalocarida
e.g. horseshoe shrimp
Malacostraca & Maxillopoda
- crabs
- krill
- woodlice & others
- barnacles
- copepods
Branchiopoda
- fairy shrimp
- water fleas
Ostracoda
seed shrimp
Maxillopoda
- tongue worms
- fish lice
- polyphyletic
Describe Crustacea
- two pairs antennae
- metamorphosis with nauplius larvae
- no general body plan
- at least two body segments
Give some examples of crustacean body plans
- head and trunk
- head, thorax and abdomen
- cephalothorax, pereon and pleon
Generalised crustacean
shrimp
Describe Crustacean diversity
- tagmosis regions
- segment numbers
- segment fusion
Describe Malacostraca
- ~40k species
- tagmosis standardised (H-T-A), with appendages on each
- gastric mill within stomach
Describe Crustacean appendages
- uniramous and biramous appendages
- evolutionary tendency towards fewer appendages and more specialised
Ramus
an article branch
Give some specialisations of crustacean appendages
- defence & predation
- sensory functions
- respiration
- reproduction
- chewing & food manipulation
- locomotion
- multi-functions
Describe Crustacean development
- direct and indirect development
- not all adult segments & appendages present at hatching
- 1st larval stage often nauplius larva with first 3 head segments & associated appendages
- periodic moults add new segments & appendages
Describe indirect Crustacean development
involves a larval stage
Describe direct Crustacean development
hatch with all segments & appendages
Describe Crustacean diversity in development
variation in larval types, stages & no. of moults
Describe a Crustacean nauplius larva
- 1st antenna
- 2nd antenna
- naupliar eye
- labrum
- mandible
Describe Crustacean diversity
- largest and smallest arthropods
- parasites, herbivores, carnivores suspension feeders
- freshwater, terrestrial and marine dwellers
- swimming, burrowing, punching, crawling between sand grains
List some Crustacea
- Stygotantalus
- Coconut crab
- Mantis shrimp
- Buoy barnacle
Describe the phylogeny of the Arthropoda
- Mandibulata, Chelicerata and Trilobites
- Mandibulata divides into Crustacea and Myriapoda
- Hexapoda
Discuss Hexapoda morphology
- three tagmataL abdomen, thorax, head
- three pairs of legs
- tympanum
- terminalia
- abdominal spiracles (tracheal system)
- propleuron
- mesopleuron
- metapleuron
- pronotum
- labial and maxillary palps
- mandible
- labrum
- ocellus
- compound eye
- one pair of antennae
Describe the Pterygota
- two pairs of wings (hind wing and fore wing)
- four Superorders: Holometabola, Paraneoptera, Polyneoptera, Paleoptera
Hexapoda includes the Classes
Insecta and Entognatha
Entognatha
- concealed mouthparts
- ametabolous development
- e.g. Springtails
Insecta
- exposed mouthparts
- includes the Subclasses Apterygota and Pterygota
Apterygota
- metabolous development
- no wings (in adult)
- bristletails, silverfish
Describe the Holometabola
- holometabolous development (egg-larva-pupa-adult)
- butterflies and moths, ants/bees/wasps, beetles, flies and others
Describe the Paraneoptera
true bugs, lice and others
Describe the polyneoptera
grasshoppers, termites, mantises and others
Describe the Paleoptera
- mayflies, dragonflies, damselflies
- hemimetabolous development (egg-nymph-adult)
Descibe insect diversity in numbers
- .>50% known biodiversity
- c.20% species have been described
- 200 million insects for each human
- 85% diversity within Holometabola
- ants & termites 1/3 of all terrestrial biomass
Insects are … in a variety of ecological niches
diverse, abundant & dominant
Describe insect ecology
- in all terrestrial habitats
- diverse in freshwater
- scarce in the sea
- decomposers, herbivores and carnivores
Give some examples of insects
- leaf cutter ants
- mayfly larvae
- Halobates (true bugs)
Describe specialisation of insect leg appendages
- cursorial foreleg (in ants)
- natatorial hind leg (in diving beetles)
- saltatorial hind leg (grasshopper)
- raptorial foreleg (in mantis)
- fossorial foreleg (in mole cricket)
Describe the morphology of insect leg appendages
- coxa
- trochanter
- femur
- tibia
- tarsus
Describe specialisation of insect mouthpart appendages
- lapping (in honey bee)
- chewing (in grasshopper)
- siphoning (in butterfly)
- piercing (in mosquito)
Describe insect mouthpart morphology
- labrum
- mandibles
- maxillae
- labium
- hypopharynx
- antennae
- compound eye
Describe wing specialisation in insect
- elytra in beetles
- hemelytra in true bugs
- halteres in flies
- leaf-like appendages in leaf insects
- scales in butterflies
- membranous appendages in bees
- fringed appendages in thrips
- tegmina in grasshopper
- stridulation in crickets
Describe insects as disease vectors
- 700 million people a year get a mosquito-borne illness
- fleas, lice, bugs, ticks, flies
Parasitoids
- lay eggs in other organisms
- wasps and flies
List some parasitic arthropods
ticks, mites, flies, fleas, lice & various crustaceans
Describe the parasitism of insects
mainly ectoparasites, some are endoparasites
Describe insect ecosystem services
- pollination facilitated by coevolution with angiosperms
- recycling
- pest control
Describe insects in bioinspiration
Insect flight provides inspiration for drone design, whereas insect materials (silks & chitins) provide inspiration for innovative oil-free materials
