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