L1 and 2 Head Flashcards
Which habitats do insect occur in?
Every terrestrial and freshwater habitat
Why are insects a good food source?
most are ~60% protein, higher than steak and soybeans
1900 species known to be edible to humans
how can insects have economic impacts
pests- economically damaging
can be valuable eg silk moths, 5500 caterpillars make 1kg silk.
What do family names end in?
-idae
What does it mean if a name is in brackets?
Described by that person, may be changed
What 7 features make insects so successful?
- evolution of an exoskeleton [less prone to desiccation, more advanced than hydrostatic skeleton]
- Small size [increases no. niches available]
- Short generation time [=fast adaptation so very successful]
- Flexible lifecycle patterns [occupy different habitats and food resources so not in comp with young].
- Internal fertilisation [ successful in dry environments]
- flight [more niches, pred. avoidance, movement]
- complex sensory systems
What would the ancestor of insects been like?
Metameric organism [each segment has a pair of jointed appendages]
Tagmatisation: head of 6 segments, Thorax of 3 and abdomen of 11 segments.
What are the 6 segments of the head?
- Labral
- Antennal [has antennae and ocelli]
- Post antennal [Has compound eye]
- Mandibular
- Maxillary
- Labial
Which head segments have mouthpart elements?
1,4,5,6
What organ is at the base of the antennae in the Pedicel?
Johnston’s organ - Stretch receptor
What 3 parts of antennae are there?
Scape, pedicel and flagellum [looks segmented, but not true segments]
Give 2 examples of different types of antennae
Moths have plumate antennae - males more plumose so can sense female sex pheromones.
Diptera have aristate antennae - arista extends off flagella
Describe the ocelli
usually 2 or 3 in a triangle formation. Not present in all insects but are important in flying insects.
Very light sensitive, possible detect the horizon.
What are antennae and mouthparts derived from?
A jointed leg
Why is saliva important?
Coats food so easy to swallow
Has digestive enzymes
Salivary gland is often modified eg to make silk or venom
Describe an insect adapted to a liquid food source
Mosquito, Diptera
Males - nectar, females - blood.
Labium hugely elongated with a U shaped gutter, holds maxillae, amdibles and hypopharynx inside.
Palps - Modified into huge fleshy lobes (labellum), senses host surface to find capillary.
Maxillae and Mandibles - v thin and elongated with cutting structures at the tip used to cut through skin
Hypopharynx - Plunges into hole in capillary. Transports saliva from head to food source
Describe mouthparts of a housefly
Lost mandibles
U shaped labium, hypopharynx in centre and salivary canal inside hypopharynx. Labrum across top of U shape. Entire space inside becomes food canal. Labellum v large, has pseudotracheae, uses capillary action to move food across to centre. Sometimes has prestomial teeth.
At rest, mouthparts relaxed and retracted into head.
When feeding, Internal changed in blood pressure extend labium causing labellum at the end to open up.
Saliva pumped down the hypopharynx to digest food source and sucked back up.
Describe the mouthparts of a butterfly
Mandibles and labrum hugely reduced
Mouthparts derived from maxillae
Maxillary palps modified into Galea, tubelike, with food canal in centre. Unfurls due to changes in internal blood pressure.
Pharyngeal pump used to suck up nectar.
Describe juvenile dragonfly labial mask
Retracts prementum and postmentum into head capsule, changes in blood pressure causes whole mouth structure to shoot forward extremely fast.
At the end of the Prementum there are palpal lobes with hooks.
Which mouthparts are the ‘upper’ and ‘lower’ lip?
labrum - upper, mandibled are behind labrum
Labium -lower
Which mouthpart attaches the labrum to the head>
Clypeus
Describe the segments of maxillae
Cardo attaches to postmentum
Stipes joins to 2 hook like cutting structures (Lacinia an galea) and the maxillary palps, for handling food.
