L8 vision and the role of colour Flashcards
what forms the cornea in a compound eye
numerous individual ommatidia
what makes up an ommatidium
a lens and nerve fibre
what is formed when all the nerve fibres from the ommatidia converge
optic nerve
what is an apposition eye
an eye in diurnal insects where the sensory receptor cells end close to the lens
what is different about the eye of nocturnal insects and what is this type of eye called
they have a clear zone between lenses and sensory components = superposition eye
what is the benefit of the clear zone
light can enter from neighbouring ommatidia
what are the 3 ancestral photoreceptors in insects
UV, blue and green
what insects have more colour receptors
Lepidoptera, Hymenoptera, Coleoptera
what are the roles of ocelli
regulate daily rhythm
respond to large sudden changes in light intensity
detect horizon or roll
where are ocelli found and how many are usually present
found between compound eyes
usually 1-3
what are the 5 parts of an ocelli
corneal lens
corneagen layer
retinal cells
pigment cells
central nervous connection
at what stage of life are insects likely to have stemmata
holometabolous larvae and sometimes adults
what is the structure of a stemma
biconvex lens, cluster of photoreceptor cells (retinula) with crystalline core
what effect do photonic crystals have on colour
produce coherent scattering = additive colour mixing
what are interference colours and how are they produced
green blue, UV, metallics
reflection in multiple layers
what effect can irregularities on an insects surface have
light scattering resulting in matt or pearly white colours
what colours do insect not synthesise and what are the name for these colour groups
flavonoids - white
carotenoids - blue, red and yellow
how can short-term colour changes occur
changes in spacing between reflective layers
pigment movement
what is crypsis
selecting background where you appear less conspicuous
what is deimatic behaviour
coloured parts suddenly being displayed, large eyespots
what is the role of deflection marks
small eye spots deflect attention from head
what is aposematic colouration
using bright colours to symbolise distastefulness due to toxins
what are the 2 types of mimicry
Batesian and mullerian
what enzyme catalyses light production
luciferase
