Star Nosed Mole Flashcards
Why is it important for the star-nosed moles to be fast hunters?
- they share their tunnels with other animals and must out compete for food
In general what are the star-nosed moles interesting adaptations?
- special mechanosensory abilities to catch and eat prey in under 1/5 s
- swim well and smell underwater by blowing bubbles and breathing them back in
How does the Eastern mole differ from the star-nosed moles?
- star-nosed mole has a pebbled, star-shaped nose with tentacles
What is an eimer’s organ?
- domed epidermal sensory organ containing merkel cells, encapsulated corpuscles (similar but smaller than pacinians corpuscle), and circle of free nerve endings
What animals have eimer’s organs?
- most species of talpids
- the ones that don’t live in dry habitats and were most likely degenerated due to harsh soil conditions
What are the three types of sensory cell?
- primary sensory cells: cell bodies at surface, receive input and send it down a fiber
- secondary sensory cells: cell bodies at surface, transmit info to nerve cell
- sensory nerve cell: cell body below surface, send dendrites to the surface
What type of sensory cell are somatosensory cells?
- sensory nerve cells
- cell body below surface and send dendrites up
What characteristics does processing of somatosensory take into account?
- threshold and distribution
- stimulus strength (measured by firing rate)
What sensations are merkel cells good at detecting?
- steady pressure and intensity
- slow adapting
- small defined receptive field
- numerous/high density
- firing increases for a smaller object
- good for determining fine spatial detail, localization and texture
What sensations are pacinian corpuscles good at detecting?
- vibration and acceleration
- rapidly adapting (fire at start and end of stimulus)
- large receptive fields
What experiments have been conducted to examine threshold and distribution of mechanosensory cells?
- von fray hair: poke skin with hair just until it bends
- stimulation with an electric rod
- indentation depths to measure threshold
What experiment has been conducted to examine stimulus strength?
- pushed rod into hairless part of cats foot
- for stronger stimulus, more firing occured
What is the difference between hairless and hairy skin?
- merkel cells are closer to the surface for hairy skin
What are free nerve endings useful for detecting?
- determine texture and differentiate between a smooth pebble and segmented worm based on the deflection of cell columns and which nerve terminals are maximally stimulated
- lateral free nerve endings: nociceptors to determine if mole has entered environment with abrasives
If a star nosed mole thinks it has encountered food, what is it sure to do?
- make contact with its 11th appendage
How does the family Talpidae have similarities?
- all have poor eyesight but mechanosensory specializations
- gather tactile information by probing environment with tip of snout (rhinarium)
How do the eimer’s organs for star nosed moles compare to the rest of the family?
- rounder, smaller and more organized
What does the star-nosed moleunculus look like?
- large nose and tentacles and large front paws
- large amount of somatosensory cortex is devoted to processing this info
For rats, what kind of mapping occurs in the cortex where sensations from the whiskers are processed?
- topographic arrangement of barrels/whisker fields in cortex that correspond to the spatial arrangement of the whiskers
How are the star-nosed moles noses mapped in the cortex?
- tentacles of nose are mapped in a ray-like pattern that matches the location of the actual tentacles in regards to each other
- mapped three times in primary sensory, secondary sensory, and caudal-lateral cortex
What can be determined by looking at mole fetuses?
- the sensitive upper and lower appendages have a head start in development
- gestation takes 30 days and the star nose develops in the third and fourth week
- in development they look similar to coast moles before the appendages peel forward and open up
