Locomotion 2: Cilial-based Locomotion in Marine Larvae

Neuronal control of Cilial Locomotion
1. Braubach et al (2006) investigated the Neuronal control of the velum in Illyanassa obsoleta and its effect on swimming activity and cilial motion
  1. Velum is the structure that is used in the movement around the WC
    1. Velum has a very complex neuronal structure and is a very important trait to have so understandably has high energy nput in its creation
  2. Measured cilial beats using photodiodes,
    1. Found two main neurotransmitters that had an effect on cililal beat frequency
      1. Serotonin increased cilial beat (dose dependent)
      2. Dopamine decrease cilial beat frequency
  3. Swimming activity mimicked that of the Seratonin and the Dopamine effects
    1. Neurotransmitters affect swimming behaviour
  4. When n antagonist was added into the water neurotransmitters stopped working
    1. Proves neurotransmitters work endogenously (inside the body)
2. Conzelmann et al (2011) investigated neuropeptide control in Platynereis larvae
  1. Whether they inhibit or promote ciliary activity
    1. Position in the WC controlled by neurotransmitters
      1. this could be controlled by other factors e.g. pressures, chemicals.
    2. This proves direct sensory - motorary function
Effects of Temperature and Viscosity
1. Podolsky & Emlet (1993) looked at the effects of temperature and viscosity on swimming speed in Sand dollar larvae
  1. Tethered larvae and measured theyre swimming speed in three temperatures
    1. 12 and 22 degree water and then 22 degree water with an increased viscosity to mimic that of 12 Degree water
      1. This then separated the effects of viscosity from the effects of temperature
  2. The higher temperature treatment showed an increased swimming speed of 40%
    1. water movement was increased by 35%
    2. 40% swimming speed and 55% water movement was due to the change in viscosity
    3. This showed an interesting component to viscosity - have to look at all aspects
Cilial-based Locomotion in Encapsulated larvae: The Embryo Stir Hypothesis
1. Goldberg et al (2008), Kuang et al (2002) The Embryo Stir Bar Hypothesis
  1. movement within the snail egg capsule is to stir up oxygen within the egg capsule
    1. Nutrient uptake within the egg
  2. there is no diffusion gradient at the edge of the egg, movement leads to gradient being formed
    1. movement leads to equal distribution of deoxygenated solute
  3. Testing the ESBH
    1. Pulmonate Gastropods used to test ESBH
      1. there is a metabolic cost to rotating so the spp show decline in rotations with aeration
    2. When exposed to hypoxia, stirring increased to boost oxygen stirring
2. Gastropods neurones were destroyed to see how it affected the stir response
  1. Found that rotations did not increase during hypoxia events
    1. added mianserin (antagonist to serotonin)
      1. this suggested serotonin was used in ESBH
Role of Locomotion in the Evolution of of non-feeding larval Echinoderms
1. Hoegh-Guldberg & Emlet (1997) looked at energetics of development in Lecithotrophic and planktotrophic sea urchins
  1. Lecithotrophic are much larger at the start due to their maternal provisioning
    1. They also move through development much quicker than Planktotrophic
  2. Generally a greater investment in lecithotrophic eggs = 2% compared to 91% investment of developmental energy requirements
  3. Also looked at how energy is used within the organism
    1. Planktotrophic organisms tend to be metabolsing for greater lengths of time
      1. energy is needed to input into moving around and feeding
        Often as much as 50% of the energy budget with returns of 4-6% from feeding
  4. No Real difference energy-wise between the two life histories.

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Locomotion 2: Cilial-based Locomotion in Marine Larvae

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	Created by Connor Joesbury almost 6 years ago