W10: Invertebrate Physiology (Physiology Of Sight: Insect Vision) [Dr. Blair] Flashcards
Cambrian explosion attributes? (3)
- ~530-540Mya.
- Modern day Phyla emergence.
- Arthropods: Trilobites (extinct) were one of the first animals to have complex, compound vision.
Types of eyes that insects have? (2)
- Simple eyes (ocelli).
- Compound eyes.
Ocelli attributes? (5)
- Simple eyes.
- Found on the heads of insects.
- Positioned in a triangular arrangement between the compound eyes (often 3 ocelli).
- Help in light detection, stabilisation & orientation.
- Narrow field of view.
Compound eyes attributes? (4)
- Composed of many ommatidia, each with its own lens.
- Produce a mosaic image of the environment.
- Wide/Panoramic field of view.
- For movement detection, image formation & colour vision.
Ommatidia attributes? (2)
- Functional parts for vision forming the facet.
- Function independently to each other in apposition eyes.
Some insects have a Pseudopupil. What’s a Pseudopupil?
= a false pupil that is an optical illusion seen in the compound eyes of some insects like the praying mantis.
Components of ommatidia? (3)
- Lens.
- Rhabdom.
- Photoreceptors.
Lens?
= consists of the cornea & cone.
Cornea?
= outer structure that initially focuses light.
Cone?
= structure in the lens that directs lights to the photoreceptors.
Rhabdom?
= structure in the ommatidia where light absorption & channeling occurs.
Photoreceptor?
= structure with retinula cells that contain pigments to detect light & convert it to electrical signals.
Insect Imaging (Compound eyes): Apposition eyes attributes? (3)
- Type of compound eye that is optimised for bright light environments.
- Each ommatidium works independently to provide sharp & detailed vision.
- Highly effective for diurnal insects that are active during the day.
Insect vision attributes? (7)
- Insects have photoreceptor cells in ommatidium (act as different wavelengths of light).
- High/Low resolution depends on the type of insect & number of ommatidium (act like pixels).
- Types of colour vision (2) come down to pigments (rhodopsins).
- Perceive a range of colours & UV light.
- More ommatidium = high resolution.
- Larger eye = more light.
- Trade-offs.
Trade-off when it comes to vision: If an insect wants to increase its resolution, it needs to increase its ommatidia, but it will need a bigger eye, so what then?
Visual adaptations.